Tonoplast-localsed proton-coupled Ca2+ Transporters encoded by cation/H+ exchanger (CAX) genes play a critical role in sequestering Ca2+ into the vacuole. These transporters may function in coordination with Ca2+ release channels, to shape stimulus-induced cytosolic Ca2+ elevation. Recent analysis of Arabidopsis CAX knockout mutants, particularly cax1 and cax3, identified a variety of phenotypes including sensitivity to abiotic stresses, which indicated that these transporters might play a role in mediating the plant’s stress response. A common feature of these mutants was the perturbation of H+-ATPase activity at both the tonoplast and the plasma membrane, suggesting a tight interplay between the Ca2+/H+ exchangers and H+ pumps. We speculate that indirect regulation of proton flux by the exchangers may be as important as the direct regulation of of Ca2+ flux. These results suggest cautions interpretation of mutant Ca2+/H+ exchanger phenotypes that may be due to either perturbed Ca2+ or H+ transport.

A growing body of epidemiological, clinical, and experimental evidence has underscored both the pharmacological potential and the nutritional value of dietary fish oil enriched in very long chain n-3 PUFAs such as docosahexaenoic acid (DHA, 22:6, n-3) and eicosapentaenoic acid (EPA, 20:5, n-3). The broad health benefits of very long chain n-3 PUFAs and the pleiotropic effects of dietary fish oil and DHA have been proposed to involve alterations in membrane structure and function, eiscoanoid metabolism, gene expresession and the formation of lipid peroxidation products, although a comprehensive understanding of the mechanisms of action has yet to be elucidated. In this review, we present data demonstrating that DHA selectively modulates the subcellular localization of lapidated signaling proeteins depending on their transport pathway, which may be universally applied to other lapidated protein trafficking. An interesting possibility raised by the current observations is that lapidated proteins may exhibit different subcellular distribution profiles in various tissues, which contain a distinct membrane lipid composition. In addition, the current findings clearly indicate that subcellular localization of proteins with a certain trafficking pathway can be subjected to selective regulation by dietary manipulation. This form of regulated plasma membrane targeting of a select subset of upstream signaling proteins may provide cells with the flexibility to coordinate the arrangement of signaling translators on the cell surface. Ultimately, this may allow organ systems such as the colon to optimally decode, respond, and adapt to the vagaries of an every changing extracellular environment.

Root vigor is an important component of transplant health and successful stand establishment in melons and other vegetable crops. Environmental factors, which impact root traits related to vigor, have been examined in some vegetable crops, but few studies on genetic variation for these traits have been published. Greenhouse experiments were conducted to evaluate early melon root vigor in a diverse selection of melon germplasm lines and cultivars. Seven accessions, representing three horticultural groups of melons (cantalupensis, inodorous, momordica), were grown in pasteurized sand, and evaluated for key root momorica), were grown in pasteurized sand, and evaluated for key root morphology traits at four stages of development. Significant differences among cultivars were observed for total root length, fine root length and root area 7, 14 and 21 days after germination. However, by 28 days, all accessions were statistically equivalent for these root traits. The entries, ‘Deltex’ and ‘PI × TDI,’ exhibited superior root vigor during the first two weeks of development, compared to the commercial cantaloupe cultivars, ‘Caravelle’ and ‘Magnum 45.’ These two lines also exhibited superior field performance for both root and vine vigor at Weslaco, and consequently were more tolerant to infection by Monosporascus cannonballus. Subsequent breeding for enhanced root vigor at Weslaco has resulted in many advanced inbreds with improved stress tolerance, vine vigor and fruit quality.

The vegetable breeding program at the Texas Agricultural Experiment Station (TAES; now Texas AgriLife Research) in Weslaco, TX, has a 60-year history of developing commercially important cultivars to meet consumer and industry needs such as improved fruit quality, disease resistance, and productivity. Western shipper melon (Cucumis melo L., Reticulatus Group) varieties are among some of the important Cucurbit crops grown in Texas for the summer fresh markets. Twelve muskmelon cultivars, including muskmelons, honeydews, and canary types, have been released since 1950 (Correa, 1964; Godfrey, 1953). Melon production in Texas has fluctuated dramatically over the years, from historic highs of more than 11,000 ha to more recent levels of »4,600 (Smith and Anciso, 2005). High costs of production, increased competition from Central America, and quality control problems have been significant factors contributing to the decline. Over the years, the vegetable breeding program at Weslaco has addressed some of the major limitations to sustainable production of high-quality melon crops in Texas. These include susceptibility to various diseases such as gummy stem blight, Monosporascus root rot and vine decline, powdery mildew, down mildew, and the Cucurbit Yellow Stunting Disorder virus. Hence, disease resistance and fruit quality are some of the major priority areas of the breeding program and have received considerable consumer, industry, and government (U.S. Department o Agriculture) support. Under the “Designing Foods for Health” grant (CSREES 2001-34402-10543, 203-34402-13647), the program has selected, for genetically enhanced levels of beneficial phytochemicals such as β-carotene as well as total sugars within TAES, commercially improved lines and wild-type germplasm. The outcomes from this program are new inbreed lines with both disease resistance and improved fruit quality.

Due to limited availability of arable land and high market demand for off-season vegetables, cucurbits (plants in the family Cucurbitacae) are continuously cultivated under unfavorable donitions in some countries. These conditions include environments that are too cold, wet, or dry, or are cool low-light winter greenhouse. Successive cropping can increase salinity, the incident of cucurbit pests, and soilborne diseases like fusarium wilt caused by Fusarium spp. These conditions cause various physiological and pathological disorders leading to severe crop loss. Chemical pest control is expensive, and always effective, and can harm the environment. Grafting can overcome many of these problems. In fact, in many parts of the world, grafting is a routine technique in continuous cropping systems. It was first commonly used in Japan during the late 1920s by grafting watermelon [Citrullus lanaltus (Thunb.) Maatsum, and Naka] onto pumpkin [Cucurbita moschata Duchesne ex. Poir] rootstocks. Soon after, watermelons were grafted onto bottle gourd [Lagenaria siceraria (Molina) Standl.] rootstocks. This practice helped control declining yield due to soilborne diseases. China produces more than half the worl’d watermelons and cucumbers (Cucumis sativus L.), and approximately 20% of these are grafted. Use of rootstocks can enhance plant vigor through vigorous attainment of soil nutrients, avoidance of soil pathogens and tolerance of low soil temperatures, salinity, and wet-soil conditions. The type of rootstock affects cucurbit plant growth, yield, and fruit quality. Cucurbit grafting is rare in the United States, but with continued loss of quality disease-free farmland along with the phase-out of methyl bromide, the U.S. cucurbit industry sees drafting as an attractive option. Some seed companies now offer watermelon transplants grafted onto squash or bottle gourd rootstocks, and some transplant facilities offer grafting services. There have been thorough analyses of cucurbit grafting in other countries, but the literature in English is limited. This review summarizes the state of the cucurbit grafting industry on a global level, translating, work published in many languages.

In order to evaluate the evaluate the effects of fatty acids on immune cell membrane structure and function, it is often necessary to maintain cells in culture. However, cell culture conditions typically reverse alterations in polyunsaturated fatty acid (PUFA) composition achieved by dietary lipid manipulation. Therefore, we hypothesized that T-cells from transgenic mice expressing the Caenorhabditis elegans n-e desaturase (fat-1) gene would be resistant to the culture-induced loss of n-3 PUFA and, therefore, obviate the need to incorporate fatty acids or homologous serum into the medium. CD4+ T-cells were isolated from (i) control wild type (WT) mice fed a safflower oil-n-6 PUFA enriched diet (SAF) devoid of n-3 PUFA, (ii) fat-1 transgenic mice (enriched with endogenous n-3 PUFA) fed a SAF diet, or (iii) WT mice fed a fish oil (FO) based diet enriched in n-3 PUFA. T-cell phospholipids isolated from WT mice fed FO diet (enriched in n-3 PUFA) and fat-1 transgenic mice fed a SAF diet (enriched in n-6 PUFA) were both enriched in n-3 PUFA. As expected, the mol% levels of both n-3 and n-6 PUFA were decreased in cultures of CD4+ T-cells from FO-fed WT mice after 3d in culture. In contrast, the expression of n-3 desaturase prevented the culture-induced decrease of n-3 PUFA in CD4+ T-cells from the transgenic mice. Carboxyfluorescein succinidyl ester (CPSE) –labeled CD4+ T-cells from fat-1/SAF vs. WT/SAF mice stimulated with anti-CD3 and anti-CD28 for 3 d, exhibited a reduced (P < 0.05) number of cell divisions. We conclude that fat-1-containing CD4+ T-cells express a physiologically relevant, n-3 PUFA enriched, membrane fatty acid composition which is resistant to conventional cell culture-induced depletion.

We compare three Arabidopsis (Arabidopsis shaliana) complex glycan1 (cgl1) alleles and report on genetic interaction with staurosporin and temperature sensitive3a (stt3a). STT3a encodes a subunit of oligosaccharyltranserase that affects efficiency of N-glycan transfer to nascent secretory proteins in the endoplasmic reticulum; cgl1 mutants lack N-acetyl-glucosaminyltransferase I activity and are unable to form complex N-glycans in the Golgi apparatus. By studying CGL1-green fluorescent protein fusions in transient assays, we show that the extra N-glycosylation site created by a point mutation in cgl1 C5 is used in planta and interferes with folding of full-length membrane-anchored polypeptides in the endoplasmic reticulum. Tunicamycin treatment or expression in the sttr3a-2 mutant relieved the folding block and migration to Golgi stacks resumed. Complementation tests with C5-green fluorescent protein and other N-glycosylation variants of CGL1 demonstrated that suppression of aberrant N-glycosylation restores activity. Interestingly, CGL1 seems to be functional also as nonglycosylated enzyme. Two other cgl1 alleles showed splicing defects of their transcripts. In cgl1 C6, a point mutation affects the 3’ splice site of intron 14, resulting in frame shifts; in cgl1-T, intron 11 fails to splice due to insertion of a T-DNA copy. Introgression of stt3a-2 did not restore complex glycan formation in cgl1 C6y or cgl1-T but supposed the N-acetyl-glucosaminyltransferase I defect in cgl1 C5. Root growth assays revealed synergistic effects in double mutants cgl1 C6 att3a-2 and cgl1-T stt3a-2 only. Besides demonstrating the conditional nature of cgl1 C5 in planta, our observations with loss-of-function alleles cgl1 C6 and cgl1-T in the stta-2 underglycosylation background prove that correct N-glycosylation is important for normal root growth and morphology in Arabidopsis.

Cell-to-cell communications in bacteria mediated by small diffusible molecules termed as autoinducers (AI) are known to influence gene expression and pathogenicity. Oligopeptides and N-acylhomoserine lactones (AHL) are major AI molecules involved in intra-specific communication in Gram-positive and Gram-negative bacteria respectively, whereas boronated-diester molecules (AI-2) are involved in inter-specific communication among both Gram-positive and gram-negative bacteria. Naturally occurring furocoumarins from grapefruit showed >95% inhibition of AI-1 and AI-2 activities based on the Vibrio harveyl based autoinducer bioassay. Grapefruit juice and furocoumarins also inhibited biofilm formation by Escherichia coli 0157:H7, Salmonella typhimaurium and Pseudomonas aeruginosa. These results suggest that grape fruit juice and furocumarins could serve as a source to develop bacterial intervention strategies targeting microbial cell signaling processes.

Grapefruit juice has been shown to increase the oral bioavailibility of many therapeutic drugs. Certain citrus bioactive compounds such as furocoumarins and flavonoids have potent inhibitory effects on cytoctochrome P450 3A4 (CYP 3A4) nzyme and P-glycoprotein. The levels of these bioactive compounds in the grapefruit juice may affect the magnitude and mechanism of grpefruit juice-induced drug interaction. The levels of three furocoumarins such as dihydroxybergamottin (DHB), paradisin A and bergamottin and flavonoids have been separted and quanitified using high-performance liquid chromatography (HPLC) in seven varieites of grapefruits and its parent pummelo. Considerable differences were observed in the levels of these bioactive compounds in different grapefruit varieties. Ray Red showed the lowest (0.492 + 0.027 DHB µg/ml, 0.059 + 0.001 µg/ml paradisin A and 0.344 + 0.030 µg/ml bergamottin) levles of all three furocoumarins and Duncan contain the highest amount of DHB (2.587 + 0.432 µg/ml) and bergamottin (1.004 + 0.068 µg/ml), where as Star Ruby contain the highest levels of paradisin (4.587 + 0.061 mg/ml), while Rio Red showed the lowest level (1.986 + 0.145 mg/ml) of narigin.

The changes in the levels of three furocoumarins such as dihydroxybergamotti (DH), paradisin A and bergamottin in Rio Red and Marsh White cultivars of grapefruits were monitored from November to May. The levels of DHB and bergamottin in both varieties of grapefruits decreased as the season progressed except for the bergamottin in Marsh White grapefruit. Influence of growing location, processing and storage on the levels of these compounds were also evaluated. Among the varieties, the highest levels of DHB (2.266 mg/ml) and bergamottin (2.411 mg/ml) were found in Flame grapefruit grown in Florida. The highest level of paradisin A was found in Rio Red grapefruit grown in California and the lowest levels were observed in Rio Red grapefruit grown organically in Texas. Hard squeezed juice contained 1.98, 1.06 and 3.03-fold more DHB, paradisin A and bergamottin, respectively as compared to processed juice. The levels of furocoumarins showed a decreasing trend in all the juices with progress of storage. Levels of furocoumarins were more in cartons container than the cans and cardboard container juices.

Phyttochemical levels in fruits and vegetables can be affected by several postharvest factors. In the present study, the effect of electron-beam) irradation was studied on grapefruit bioactive compounds. 'Rio Red' and 'Marsh White' grapefruits were irradiatred with E-beam at 0, 2., 2.5, 5.0, and 10.0 kGy. Changes of various bioactive compounds, such as vitamin C, flavonoids, carotenoids, furocoumarins, and limonoids, were measured. The acidity decreased slightly with an increasing E-beam dose, whereas the total soluble solids were increased. Irradiation did not affect the vitamin C contact of 1 kGy; however, doeses beyond 1 kGy significantly reduced the vitamin C content. Lycopene and β-carotene content slightly increased. Dihydroxybergamottin levels exhibited a decreasing trend, while the bergamottin content did not change. Naringin, a major flavonoid of grapefruid, showed a significant increase over the control at 10 kGy in both 'Rio Red' and 'Marsh White'. Nomilin continued to decrease wtih an increasing does of E-beam irradiation, while limonin levels remained the same at all of the doeses. Low-dose E=beam irradiation has very little effect on the bioactive compounds and offers a safe alternative to existing postharvest treatments for the disinfection and decontamination of grapefruit.

Vegetabale grafting began in the 1920s using resistant rootstock to control soilborne diseases. This process is now common in Asia, parts of Europe, and the Middle East. In Japan and Korea, most of the cucurbita and tomatoes (Lycopersicon esculentum Mill.) grown are grafted. This practice is rare in the United States, and there have been few experiments to determine optimal grafting production practices for different geographical and climatic regions in America. This is beginning to change as a result of the phase out of methyl bromide. The U.S. cucurbit and tomato industries are evaluating grafting as a viable option for disease control. Because reports indicate that type of rootstock alters yield and quality attributes of the scion fruit, some seed companies are investigating grafting as a means to improve quality. It has been reported that pH, flavor, sugar, color, carotenoid content, and texture can be affected by grafting and the type of rootstock used. Reports vary on whether grafting effects are advantageous or deleterious, but it is usually agreed that the rootstock/scion combination must be carefully chosen for optimal fruit quality. Additionally, it is important to study rootstock/scion combination under multiple climatic and geographic conditions because many rootstocks have optimal temperature and moisture ranges. This report gives an overview of the effect of grafting on vegetable quality.

Phytochemical levels in fruits and vegetables can be affected by several postharvest factors. In the present study, the effect of electron-beam (E-beam) irradiation was studied on grapefruit bioactive compounds. ‘Rio Red’ and ‘Marsh White’ grapefruits were irradiated with E-beam at 0, 1.0, 2.5, 5.0, and 10.0 kGy. Changes of various bioactive compounds, such as vitamin C, flavonoids, carotenoids, furocoumarins, and limonoids, were measured. The acidity decreased slightly with an increasing E-beam dose, whereas the total soluble solids were increased. Irradiation did not affect the vitamin C content at 1 kGy; however, doses beyond 1 kGy significantly reduced the vitamin C content. Lycopene and β-carotene did not change significantly from the irradiation. Lycopene levels decreased as the E-beam dose increased, with the β-carotene content slightly increased. Dihydroxybergamottin levels exhibited a decreasing trend, while the bergamottin content did not change. Naringin, a major flavonoid of grapefruit, showed a significant increase over the control at 10 kGy in both ‘Rio Red’ and ‘Marsh White’. Nomilin continued to decrease with an increasing dose of E-beam irradiation, while limonin levels remained the same at all of the doses. Low-dose E-beam irradiation has very little effect on the bioactive compounds and offers a safe alternative to existing postharvest treatments for the disinfection and decontamination of grapefruits.

Antioxidant fractions from two different citrus species such as Rio Red (Citrus paradise Macf.) and Sour orange (Citrus aurantium L.) were extracted with five different polar solvents using Soxhlet type extractor. The total phenolic content of the extracts was determined by Folin-Ciocalteu method. Ethyl acetate extract of Rio Red and Sour orange was found to contain maximum phenolics. The dried fractions were screened for their antioxidant activity potential using in vitro model systems such as 1,1-diphenyl-2-picryl hydrazyl (DPPH), phosphomolybdenium method and nitroblue tetrazolium (NBT) reduction at different concentrations. The methanol:water (80:20) fraction of Rio Red showed the highest radical scavenging activity 42.5%, 77.8% and 92.1% at 250, 500 and 1000 ppm, respectively, while methanol:water (80:20) fraction of Sour orange showed the lowest radical scavenging activity at all the tested concentrations. All citrus fractions showed good antioxidant capacity by the formation of phophomolybdenum complex at 200 ppm. In addition, superoxide radical scavenging activity was assayed using non-enzymatic (NADH/phenaxine methosulfate) superoxide generating system. All the extracts showed variable superoxide radical scavenging activity. Moreover, methonal:water (80:20) extract of Rio Red and methanol extract of Sour orange exhibited marked reducing power in potassium ferricyanide reduction method. The data obtained using above in vitro models clearly established the antioxidant potential of citrus fruit extracts. However, comprehensive studies need to be conducted to ascertain the in vitro bioavailability, safety and efficacy of such extracts in experimental animals. To the best of our knowledge, this is the first report on antioxidant activity of different polar extracts from Rio Red and Sour oranges.

Potential cancer preventive constituents of our orange (Citrus aurantium L.) were isolated and identified from EtOAc extract of sour orange. Crude EtAc extract was purified using silica gel column chromatography to isolate two putative bioactive compounds. The purity of the isolated compounds was analyzed by TLC and HPLC. The structures of the two compounds were identified by one-dimensional (1H, 13C) and two-dimensional (1H-H and 1H- 13C) NMR experiments as isolimonic acid and a novel compound named as ichanexic acid. Stereochemical assignment of the protons for both the compounds was made using one-dimensional nuclear Overhauser enhancement (nOE) experiments. The identified compounds were tested for the inhibition of human colon cancer cells (HT-29) proliferation, apatosis, and on non-cancerous (COS-1 fibroblast) cells. Cell proliferation, arrest of cell growth, and nuclear staining methods, respectively. The MTT assay indicated that both the compounds exhibited differential inhibition at various concentrations. Significant arrest of cell growth by isolimonoic acid was noted within 24 h of treatment on the HT-29 colon cancer cells at a concentration as low as 5.0 mM (P – 0.005) and by ichanexic acid at 10.0 mM P – 0.011). None of the compounds exerted any apparent cytostatic effects on the non-cancerous COS-1 fibrobast cells. Both the compounds exerted nearly 4- to 5-fold increase in the counts of G2/M stage cells at 5 mM indicating a potential role in the cell cycle arrest as well as possible lead structures for the development of cancer chemoi-preventive and therapeutic agents. To the best of our knowledge, this is the first report on isolation, identification of isolimonic acid in its native form, and compound 2 was found to a novel and identified as ichanexic acid.

Extraction efficiency of five different solvents on the antioxidant capacities of pummelo and navel oranges was measured by five widely used antioxidant methods. Freeze-dried edible parts of pummelo and navel oranges were extracted with five different solvents such as hexane, ethyl acetate, acetone, methanol and methanol:water (8:2). The total phenolic content of the extracts was determined by Folin-Ciocalteu method and expressed as catechin equivalents. The highest phenolic content was obtained from ethyl acetate and the minimum phenolic content was found in methanol extract. The dried extracts were screened for their radical scavenging activity using three different methods such as α,α-diphenyl-β-picrylhydrazyl (DPPH), 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABATS) radical assay and ORAC methods. Ethyl acetate extract from navel orange and pummelo was found to be most active radical scavenging activity, whereas hexane extract from pummelo and methanol extract from navel orange was found to be lowest activity. Moreover, all the extracts from pummelo and navel orange were studied for their antioxidant capacity by the formation of phosphomolybdenum complex and reducing power by potassium ferricyanide reduction method at various concentrations. The order of antioxidant capacity of pummelo and navel orange was found to be ethyl acetate > acetone > MeOH:water > methanol > hexane and ethyl acetate > MeOH:water > acetone > methanol > hexane, respectively. Acetone and methanol extracts from pummelo and navel oranges showed highest reducing power than other extracts of 1000 mg/ml. Significant differences in antioxidant capacity were found between the values obtained by the same method in different solvents and as well as each extract antioxidant capacity obtained by the different method. Results of the present study may be due to the extent of antioxidant capacity of each extract is in accordance with the amount of carotenoids, phenolics and vitamin C present in the extracts.

Bioactive food components containing n-3 polyunsaturated fatty acids (PUFA) modulate multiple determinants that link inflammation to cancer initiation and progression. Therefore, in this study, fat-1 transgenic mice, which convert endogenous n-6 PUFA to n-3 PUFA in multiple tissues, were injected with azoxymethane followed by three cycles of dextran sodium sulfate (DSS) to induce colitis-associated cancer. Fat-1 mice exhibited a reduced number of colonic adenocarcinomas per mouse (1.05 ± 0.29 versus 2.12 ± 0.51, P 0.033), elevated apoptosis (P – 0.03), and a decrease in n-6 PUFA-derived eicosanoids, compared with wild-type (wt) mice. To determine whether the chemoprotective effects of n-3 PUFA could be attributed to its pleiotropoic anti-inflammatory properties, colonic inflammation and injury scores were evaluated 5 days after DSS exposure followed by either a 3-day or 2-week recovery period. There was no effect of n-3 PUFA at 3 days. However, following a 2-week recovery period, colonic inflammation and ulceration scores returned to pretreatment levels compared with 3-day recovery only in fat-1 mice. For the purpose of examining the specific reactivity of lymphoid elements in the intestine, CD3+ T cells, CD4+ T helper cells, and macrophages from colonic lamina propria were quantified. Comparison of 3-day versus 2-233k recovery time points revealed that fat-I mice exhibited decreased (P < 0.05) CD3+, DC4+ T helper, and macrophage cell numbers per colon as compared with wt mice. These results suggest that the antitumorigenic effect of n-3 PUFA may be mediated, in part, via its anti-inflammatory properties. [Cancer Res 2008; 68(10):3985-91]

Protein Ni-glycosylation in the endoplasmic reticulum (ER) and in the Golgi apparatus is an essential process in eukaryotic cells. Although the N-glycosylation pathway in the ER has been shown to regulate protein quality control, salt tolerance, and cellulose biosynthesis in plants, no biological roles have been linked functionally to N-glycan modifications that occur in the Golgi apparatus. Herein, we provide evidence that mutants defective in N-glycan maturation, such as complex glycan 1 (cgl1), are more salt-sensitive than wild type. Salt stress caused growth inhibition, aberrant root-tip morphology, and callose accumulation in cgl1, which were also observed in an ER oligosaccharyltransferase mutant, staurosporin and temperature sensitive 3a (stt3a). Unlike stt3a, cgl1 did not cause constitutive activation of the unfolded protein response. Instead, aberrant modification of the plasma membrane glycoprotein KORRIGAN 1/RADIALLY SWOLLEN 2 (KOR1/RSW2) that is necessary for cellulose biosynthesis occurred in cgl1 and stt3a. Genetic analyses identified specific interactions among rsw2, stt3a, and cgl1 mutations, indicating that the function of KOR1/RSW2 protein depends on complex N-glycans. Furthermore, Cellulose deficient rsw-1 and rsw2-2 plants were also salt-sensitive. These results establish that plant protein N-glycosylation functions beyond protein folding in the ER and is necessary for sufficient cell-wall formation under salt stress.

The primary purpose of grafting vegetables worldwide has been to provide resistance to soilborne diseases. The potential loss of methyl bromide as a soil fumigant combined with pathogen resistance to commonly used pesticides will make resistance to soilborne pathogens even more important in the future. The major disease problems addressed by grafting include fusarium wilt, bacterial wilt, verticillium wilt; monosporascus root rot, and nematodes. Grafting has also been shown in some instance to increase tolerance to foliar fungal diseases, viruses, and insect. If the area devoted in grafting increases in the future, there will likely be a shift in the soil microbial environment that could lead to the development of new diseases or changes in the pathogen population of current diseases. This shift in pathogen populations could lead to the development of new diseases or the re-emergence of previously controlled diseases. Although grafting has been demonstrated to control many common diseases, the ultimate success will likely depend on how well we monitor for changes in pathogen populations and other unexpected consequences.

Insects are capable of readjusting their digestive regimes in response to dietary challenge. Cowpea bruchids (Callosobruchus muculatus) strongly induce C. maculates cathepsin B-like cysteine protease 1 (CmCatB1) transcripts when fed diet containing a soybean cysteine protease inhibitor soyacystatin N (scN). CmCatB1 shares significant sequence similarity with cathepsin B-like cysteine proteases. In this study, we isolated another cDNA, namely CmCatB2 that encodes a protein sequence otherwise identical to CmCatB1, but tacking a 70-amino-acid internal section. CmCatB1 and CmCatB2 probably resulted from alternate splicing events. Only the CmCatB1 transcript, however, exhibited differential expression in response to dietary scN. Further, this expression was only detectable in larvae, which is the developmental stage associated with food ingestion. The scN-activated and developmentally regulated CmCatB1 expression pattern suggests it may have a unique function in insect counter-defence against antinutritional factors. Heterologously expressed recombinant CmCatB1 protein exhibited enzymatic activity in a pH-dependent manner. Activity of the protein was inhibited by both the cysteine protease inhibitor E-54 and the cathepsin B-specific inhibitor CA-074, verifying its cathepsin B-like cysteine protease nature. Interestingly, the enzymatic activity was unaffected by the presence of scN. Together, we have provided functional evidence suggesting that CmCatB1 confers inhibitor-insensitive enzymatic activity to cowpea bruchids, which is crucial for insect survival when challenged by dietary protease inhibitors.

The action of extracts from anthocyanin-enriched plums and peaches on growth and differentiation was studied with human colon cancer cells. Growth inhibitory effects were observed in Caco-2, SW1116, HT29 and NCM460 cells. In Caco-2 cells but not in the other cells studied there was evidence for increased differentiation as judged by increased activity of alkaline phosphatase and dipeptidyl peptidase. A differentiating effect on Caco-2 cells was not seen with cyaniding or cyaniding-3 glucoside but the action of the fruit extracts was additive with the action of butyrate and with the MEK1/2 inhibitor U0126. Functionation using C18 indicated activity resided within a fraction containing anthocyanins but further fractionation using LH-20 suggested that most of the activity was in a fraction containing anthocyanins but further fractionation using LH-20 suggested that most of the activity was in a fraction containing polyphenols other than anthocyanins. It was concluded that several peach and plum phenolic molecules can influence growth and differentiation in human colon cells.

A study was conducted among the attendees of the Annual Texas Mater Gardener Conference held in College Station, TX, in May 2006. Participants were asked to complete a 31-question survey to understand their knowledge of the nutritional attributes and storage guidelines of pecans (Carya illinoinensis). A total of 177 attendees completed the survey, corresponding to 32.2% of the total number of conference attendees. Participants were asked to complete the survey to test their nutritional knowledge, purchasing attitude, consumption, and storage preferences of pecans (23 questions). The remaining eight questions requested biographical and demographical information. Results revelaed that tast was the main reason people ate pecans followed by the perception of eating something healthy. Over fouor-fifths of survey respondents knew that pecans contain heart-healthy fats and proteins. Approximately one-half of the respondents were aware that pecans are a source of minerals and antioxidants. However, 86.9% of the respondents believed that consuming pecans could lead to an increase in the levels of low-density lipoprotein (“bad”) cholesterol, which is opposite of what was reported by clinical studies. Over one-third of the respondents did not think that pecans require refrigeration to maintain flavor. Moreover, over half of the respondents did not believe that pecans store better if kept in the shell. Although the sample was limited because it was one of convenience, in general, respondents had good eating habits and a very positive attitude toward pecans. However, more educational programs are necessary to inform them about the health properties and proper storage methods of pecans.

Six citrus flavonoids were tested for antineoplastic activity. The hamster cheek pouch model was utilized, and the solutions of the flavonoids (2.0-2.5%) and the solution of the carcinogen, 7,12-dimthetyylbenz[a]anthracene (0.5%), were applied topically to the pouches. The pouches of the positive controls were treated with the solvent used to dissolve the flavonoids and the solution of the carcinogen. The data show that 4 flavonoids (besperetin, neohesperidin, tangereti, and nobiletin) were inactive. The results with naringin and naringenin show that both of these flavonoids significantly lowered tumor number [5.00 (control group), 2.53 (naringin group), and 3.25 (naringenin group)]. Naringin also significantly reduced tumor burden [269 mn3 (control group) and 77.1 mn3 (naringin group)]. The data suggest that naringin and naringenin, 2 flavonoids found in high concentrations in grapefruit, may be able to inhibit the development of cancer.

Nutrition recommendations worldwide emphasize ingestion of plant-based diets rather than diets that rely primarily on animal products. However, this plant-based diet could limit the intake of essential nutrients such as calcium. Osteoporosis is one of the world’s most prevalent nutritional disorders, and inadequate dietary calcium is a known contributor to the pathophysiology of this condition. Previously, we have modified carrots to express increased levels of a plant calcium transporter (sCAX1), and these plants contain ≈ 2-fold-higher calcium content in the edible portions of the carrots. However, it was unproven whether this change would increase the total amount of bioavailable calcium. In randomized trials, we labeled these modified carrots with isotopic calcium and fed them to mice and humans to assess calcium bioavailability. In mice feeding regimes (n = 120), we measured 45Ca incorporation into bones and determined that mice required twice the serving size of control carrots to obtain the calcium found in sCAX1 carrots. We used a dual-stable isotope method with 42Ca-labeled carrots and l.v. 46Ca to determine the absorption of calcium from these carrots in humans. In a cross-over study of 15 male and 15 female adults, we found that when people were fed csCAX1 and control carrots, total calcium absorption per 100 g of carrots was 41% ± 2% higher in sCAX1 carrots. Both the mice and human feeding studies demonstrate increased calcium absorption from sCAX1-expressing carrots compared with controls. These results demonstrate an alternative means of fortifying vegetables with bioavailable calcium.

The Arabidopsis (Arabidopsis thaliana) cation calcium exchangers (CCXs) were recently identified as a subfamily of cation transporters; however, no plant CCXs have been functionally characterized. Here, we show that Arabidopsis AtCCX3 (At3g14070) and AtCCX4 (At1g54115) can suppress yeast mutants defective in Na+, K+, and Mn2+ transport. We also report high-capacity uptake of 86Rb+ uptake in AtCCX3 cells by excess Na+, K+, and Mn2+. Functional epitope-tagged AtCCX3 fusion proteins were localized to endomembranes in plants and yeast. In Arabidopsis, AtCCX3 is primarily expressed in flowers, while AtCCX4 is expressed through the plant. Quantitative polymerase chain reaction showed that expression of AtCCX3 increased in plants treated with NaCL, KC1, and MnCl2. Insertional mutant lines of AtCCX3 and AtCCX4 displayed no apparent growth defects; however, over expression of AtCCX3 caused increased Na+ accumulation and increased 86Rb+ transport. Uptake of 86Rb+ increased in tonoplast-enriched membranes isolated from Arabidopsis lines expressing CCX3 driven by the cauliflower mosaic virus 35S promoter. Overexpression of AtCCX3 in tobacco (Nicotiana tabacum) produced lesions in the leaves, stunted growth, and resulted in the accumulation of higher levels of numerous cations. In summary, these findings suggest that AtCCX3 is an endomembrane-localized H+-dependent K+ transporter with apparent Na+ and Mn2+ transport properties distinct from those of previously characterized plant transporters.

The crude hexane and chloroform extracts from the fruit rinds of Garcinia cowa and Garcinia pedunculata were studied for their antibacterial activity against some food borne pathogens and spoilage bacteria such as Bacillus cereus, Bacillus coagulans, Bacillus subtilis, Staphylococcus aureus and Escherischia coli. The minimum inhibitory concentrations (MICs) of the extracts determined by the agar dilution method were ranging from 15 to 500 mg/ml and 300 to 1250 mg/ml for G. cowa and G. pedunculata, respectively. However, the hexane and chloroform extracts from the fruit rinds of G. cowa exhibited marked inhibitory effect against all the test organisms and were more effective than that of G. pedunculata extracts. The antibacterial activity of all the extracts was more pronounced against the tested Gram-positive bacteria than the tested Gram-negative bacterium. Furthermore, this study is the first report on the in vitro antibacterial activity of extracts from the fruit rinds of G. cowa and G. pedunculata.

Bean rust, caused by Uromyces appendiculatus (Pers.:Pers.) Unger, is an important disease of common bean (Phaseolus vulgaris L.). A coupling-phase random amplified polymorphic DNA (RAPD) marker QAD12.550 previously was identified to be linked (no recombination) by Ur-7 of Middle American (MA) origin for specific rust resistance in the common bean cross of Great Northern (GN) 1140 × GN Nebr. #1. However, a sequence characterized simplified region (SCAR) marker for Ur-7 present in GN1140 has not been reported. Our objectives were to convert the RAPD marker OAD12.550 most tightly linked to UR-7 to a SCAR marker SOAD12.537 for use as a marker-assisted selection tool, and survey the presence or absence of the SCAR marker SOAD12.537 in 90 MA and Andean bean genotypes for determining the genetic relationship of UR-7 with Ur-6. The coupling-phase SCAR marker SOAD 12.537 based on a specific forward (5’-AAGAGGGCGTGAGATCGTCG-31’) and reverse (5’-AAGAGGGCGTCTTGAAGGTT-e’) primer pair showed no recombination with Ur-7 in an F2 population of the GN1140 × Nebr. #1 cross. The SCAR marker was also present in pinto US-5 from which the rust resistance ofGN1140 was derived and in the closely related pinto US-14. The cosegregating SCAR marker identified MA pinto bean cultivars/lines Qiathe, Bill Z, Apache, Montrose, BelDak-RR-1 and-2, and CO 12783 that have rust resistance gene Ur-6 and also have U4-7, identified in earlier literature as Urc, due to presence of the marker. Other cultivars/lines with Ur-6 such as Weihing, Burke, Kodiak, Topaz, Golden Gate Wax, BelMiDakMi 1-23, and other Colorado breeding lines lack Ur-7 because of absence of the SCAR marker for the MA gene. The SCAR marker linked to Ur-7 on linkage group 11 of the core P. valgaris linkage map can identify a phenotypically hidden resistance gene, and along with markers for other rust resistance genes, can be utilized to pyramid multiple genes for more durable rust resistance.

Grapefruits were found to contain d-glucaric acid, which has anticancer properties. In the present investigation, a method has been developed for the quantification of d-glucaric acid in grapefruit by high-performance liquid chromatography (HPLC) using a simple isocratic mobile phase with detection at 210 nm. Grapefruit samples were homogenized, centrifuged and filtered through a 0.45 mm membrane and injected into a HPLC system. The developed method was used for the quantification of d-glucaric acid in nine widely used grapefruit varieties. Furthermore, the identity of d-glucaric acid was confirmed by mass spectra. Seasonal variation of d-glucaric acid within the individual varieties were also measured in fruits harvested during November, February, and May. The overall trend of d-glucaric acid level was increased from early to late season fruits. The developed method has a sensitivity of d-glucaric acid as low as 0.05 mg with an accuracy and precision >95%. This method was found to be simple, fast, accurate, and reproducible. Moreover, the identity of d-glucaric acid was confirmed by mass spectra. Additionally, the labor intensity and cost of sample preparation were greatly reduced as compared to reported methods. This is the first report on quantification of d-glucaric acid in different varies of grapefruits from three harvesting sessions.

Autoinducer-2 (AI-2) molecules are used by several microorganisms to modulate various processes, including bioluminescence, biofilm formation, and virulence expression. Certain food matrices, including ground beef extracts, posses compounds capable of inhibiting AI-2 activity. In the present study, we identified and characterized these AI-2 inhibtors from ground beef extract using hexane solvent extraction and gas chromatography. Gas chromatographic analysis revealed the presence of several fatty acids such as palmic acid (C16:0), oleic acid (C18:1 ω9) and linoleic acid (C18:2 ω6) that were capable of inhibiting AI-2 activity. These fatty acids were tested (using Vibrio harveyi BB170 and MM32 reporter strains) at different concentrations (1, 5, and 10 mM) to identify differences in the level of AI-2 activity inhibition. AI-2 inhibition ranged from 25 to 90%. A mixture of these fatty acids (prepared at concentrations equivalent to those present in the ground beef extract) produced 52 to65% inhibition of AI-2 activity. The fatty acid mixture also negatively influenced Escherichia coli K-12 biofilm formation. These results demonstrate that both mediu- and long-chain fatty acids in ground beef have the ability to interfere with AI-2-based cell signaling.

More than 20 genes in the Arabidopsis genome encode proteins similar to phosphatases that act on the carboxyl-terminal domain (CTD) of RNA polymerase II. One of these CTD-phosphatase-like (CPL) proteins, CPL2, dephosphorylates CTD-SER5-PO, in an interact RNA polymerase II complex and contains a double-stranded (ds)-RNA-binding motif (DRM). Although the dsRNA—binding activity of CPL2 DRM has not been shown to date, T-DNA insertion mutants that express (CPL2 variants lacking either a part of DRM (cpl2-1) or the entire DRM (cpl2-2) exhibited leaf expansion defects, early flowering, low fertility, and increased salt sensitivity, cpl2 mutant plants produced shorter hypocotyls than wild-type plants in the light, but were indistinguishable from wild type in the dark. CPL2 was expressed in shoot and root meristems and vasculatures, expanding rosette leaves, and floral organs suggesting a focal role for growth. Microarray and RT-PCR analyses revealed that basal levels of several auxin-responsive transcripts were reduced in cpl2. On the other hand, the levels of endogenous auxin and its conjugates were similar in wild type and cpl2. Overexpression of ARFS but not all activator ARF transcription factors restored the auxin-responsive DR5-GUS reporter gene expression and the leaf expansion of cpl2 mutant plants but not early flowering phenotype. These results establish CPL2 as a multifunctional regulator that modulates plant growth, stress, and auxin responses.

Molecular genetic studies on the model plant Arabidopsis thaliana often involve multiple rounds of Agrobacterium- mediated transformation. Such procedures require multiple marker genes that would allow for efficient selection of transgenic plants in each cycle of transformation. Here, we report on a selection marker cassette based on a codon-modified glyphosate N-acetyltransferase (GAT) gene whose expression is driven by a powerful EL2Ω promoter. After introduction of the GAT expression cassette into A. thaliana via Agrobacterium-mediated transformation, glyphosate-resistant primary transformants are efficiently selected by glyphosate, either added to the culture medium or by spraying a glyphosate solution onto seedlings grown in soil. Robust glyphosate-resistant phenotypes are always associated with the presence of the GAT cassette. In addition, RT-PCR analysis of T2 transformants has demonstrated that resistance to glyphosate is associated with higher levels of GAT expression. Resistance conferred by GAT is specific to glyphosate and not to other commonly used selection chemical compounds. These results demonstrate the versatility of the GAT cassette suitable for both large-scale, soil-based selection system of transgenic plants as well as their characterization in vitro.

Perturbing CAX1, an Arabidopsis vacuolar H+/Ca2+ antiporter, and the related vacuolar transporter CAX3, has been previously shown to cause severe growth defects; however, the specific function of CAX3 has remained elusive. Here, we describe plant phenotypes that are shared among cax1 and cax3 including an increased sensitivity to both abscisic acid (ABA) and sugar during germination, and an increased tolerance to ethylene during early seedling development. We have also identified phenotypes unique to cax3, namely salt, lithium and low pH sensitivity. We used biochemical measurements to ascribe these cax3 sensitivities to a reduction in vacuolar H+/Ca2+ transport during salt stress and decreased plasma membrane H+-ATPase activity. These findings catalog an array of CAX phenotypes and assign a specific role for CAX 3 in response to salt tolerance.

Potassium (K+) homeostasis is essential for diverse cellular processes, although how various cation transporters collaborate to maintain a suitable K+ required for growth and development is poorly understood. The Arabidopsis (Arabidopsis thaliana) genome contains numerous cations: proton antiporters (CHX), which may mediate K+ transport; however, the vast majority of these transporters remain uncharacterized. Here, we show that AtCHX13 (At2g30240) has a role in K+ acquisition. AtCHX13 suppressed the sensitivity of yeast (Sacchromyces cerevisiae) mutant cells defective in K+ uptake. Uptake experiments using 86Rb+ as a tracer for K+ demonstrated that AtCHX13 mediated high-affinity K+ uptake in yeast and in plant cells with a Km of 136 and 196 mM, respectively. Functional green fluorescent protein-tagged versions localized to the plasma membrane of both yeast and plant. Seedlings of null chx13 mutants were sensitive to K+ deficiency conditions, whereas overexpression of AtCHX13 reduced the sensitivity to K+ deficiency. Collectively, these results suggest that AtCHX13 mediates relatively high-affinity K+ uptake, although the mode of transport is unclear at present. AtCHX13 expression is induced in roots during K+-deficient conditions. These results indicate that one role of AtCHX13 is to promote K+ is limiting in the environment.

Plants can accumulate, constitutively and/or after induction, a wide variety of defense compounds in their tissues that confer resistance to herbivorous insects. The naturally occurring plant resistance gene pool can serve as an arsenal in pest management via transgenic approaches. As insect-plant interaction research rapidly advances, it has gradually become clear that the effects of plant defense compounds are determined not only by their toxicity toward target sites, but also by how insects respond to the challenge. Insect digestive tracts are not passive targets of plant defense, but often can adapt to dietary challenge and successfully deal with various plant toxins and anti-metabolites. This adaptive response has posed an obstacle to biotechnology-based pest control approaches, which underscores the importance of understanding insect adaptive mechanisms. Molecular studies on the impact of protease inhibitors on insect digestion have contributed significantly to our understanding of insect adaptation to plant defense. This review will focus on exposing how the insect responds to protease inhibitors by both qualitative and quantitative remodeling of their digestive proteases using the cowpea bruchid-soybean cysteine protease inhibitor N system.

Our understanding of the role of plant proteins in defense against herbivores lags behind that of proteins involved in defense against pathogens. However, recent microarray and proteomic approaches have revealed that a broader array of proteins may be involved with defense against herbivores than previously appreciated (Felton, 2005). Here, we discuss defense proteins that function post ingestively, some of which are directly toxic while others exert their defense by impairing nutrient utilization. Our purpose is not to provide an extensive review of the topic, But to highlight recent findings and suggest new avenues for research. We refer the reader to reviews that provide more extensive coverage (for review, see Carlini and Grossi-de-Sa, 2002; Kehr, 2006; Shindo and Van Der Hoorn, 2008). Because arthropods possess a diverse range of feeding habits and styles, including chewing as well as phloem-or xylem-feeding species, arthropod-induced proteins (AIPs) may be regulated by multiple signaling hormones, including jasmonic add (JA), salicylic acid, and / or ethylene.