An Ethylene-Protected Achilles' Heel of Etiolated Seedlings for Arthropod Deterrence

A small family of Kunitz protease inhibitors exists in Arabidopsis thaliana, a member of which (encoded by At1g72290) accomplishes highly specific roles during plant development. Arabidopsis Kunitz-protease inhibitor 1 (Kunitz-PI;1), as we dubbed this protein here, is operative as cysteine PI. Activity measurements revealed that despite the presence of the conserved Kunitz-motif the bacterially expressed Kunitz-PI;1 was unable to inhibit serine proteases such as trypsin and chymotrypsin, but very efficiently inhibited the cysteine protease RESPONSIVE TO DESICCATION 21. Western blotting and cytolocalization studies using mono-specific antibodies recalled Kunitz-PI;1 protein expression in flowers, young siliques and etiolated seedlings. In dark-grown seedlings, maximum Kunitz-PI;1 promoter activity was detected in the apical hook region and apical parts of the hypocotyls. Immunolocalization confirmed Kunitz-PI;1 expression in these organs and tissues. No transmitting tract (NTT) and HECATE 1 (HEC1), two transcription factors previously implicated in the formation of the female reproductive tract in flowers of Arabidopsis, were identified to regulate Kunitz-PI;1 expression in the dark and during greening, with NTT acting negatively and HEC1 acting positively. Laboratory feeding experiments with isopod crustaceans such as Porcellio scaber (woodlouse) and Armadillidium vulgare (pillbug) pinpointed the apical hook as ethylene-protected Achilles? heel of etiolated seedlings. Because exogenous application of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and mechanical stress (wounding) strongly up-regulated HEC1-dependent Kunitz-PI;1 gene expression, our results identify a new circuit controlling herbivore deterrence of etiolated plants in which Kunitz-PI;1 is involved

Gluten Detection Methods and Their Critical Role in Assuring Safe Diets for Celiac Patients

Celiac disease, wheat sensitivity, and allergy represent three different reactions, which may occur in genetically predisposed individuals on the ingestion of wheat and derived products with various manifestations. Improvements in the disease diagnostics and understanding of disease etiology unveiled that these disorders are widespread around the globe affecting about 7% of the population. The only known treatment so far is a life-long gluten-free diet, which is almost impossible to follow because of the contamination of allegedly “gluten-free” products. Accidental contamination of inherently gluten-free products could take place at any level from field to shelf because of the ubiquity of these proteins/grains. Gluten contamination of allegedly “gluten-free” products is a constant threat to celiac patients and a major health concern. Several detection procedures have been proposed to determine the level of contamination in products for celiac patients. The present article aims to review the advantages and disadvantages of different gluten detection methods, with emphasis on the recent technology that allows identification of the immunogenic-gluten peptides without the use of antibodies. The possibility to detect gluten contamination by different approaches with similar or better detection efficiency in different raw and processed foods will guarantee the safety of the foods for celiac patients

Comparative Lipidomic Analysis Reveals Heat Stress Responses of Two Soybean Genotypes Differing in Temperature Sensitivity

Heat-induced changes in lipidome and their influence on stress adaptation are not well-defined in plants. We investigated if lipid metabolic changes contribute to differences in heat stress responses in a heat-tolerant soybean genotype DS25-1 and a heat-susceptible soybean genotype DT97-4290. Both genotypes were grown at optimal temperatures (OT; 30/20 °C) for 15 days. Subsequently, half of the plants were exposed to heat stress (38/28 °C) for 11 days, and the rest were kept at OT. Leaf samples were collected for lipid and RNA extractions on the 9th and 11th days of stress, respectively. We observed a decline in the lipid unsaturation level due to a decrease in the polyunsaturated linolenic acid (18:3) content in DS25-1. When examined under OT conditions, DS25-1 and DT97-4290 showed no significant differences in the expression pattern of the Fatty Acid Desaturase (FAD) 2-1A, FAD2-2B, FAD2-2C, FAD3A genes. Under heat stress conditions, substantial reductions in the expression levels of the FAD3A and FAD3B genes, which convert 18:2 lipids to 18:3, were observed in DS25-1. Our results suggest that decrease in levels of lipids containing 18:3 acyl chains under heat stress in DS25-1 is a likely consequence of reduced FAD3A and FAD3B expression, and the decrease in 18:3 contributes to DS25-1′s maintenance of membrane functionality and heat tolerance

Pattern of Protein Expression in Developing Wheat Grains Identified through Proteomic Analysis

Grain development is one of the biological processes, which contributes to the final grain yield. To understand the molecular changes taking place during the early grain development, we profiled proteomes of two common wheat cultivars P271 and Chinese Spring (CS) with large and small grains, respectively at three grain developmental stages (4, 8, and 12 days post anthesis). An iTRAQ (isobaric tags for relative and absolute quantitation) based proteomics approach was used for this purpose. More than 3,600 proteins were reported to accumulate during early grain development in both wheat cultivars. Of these 3,600 proteins, 130 expressed differentially between two wheat cultivars, and 306 exhibited developmental stage-specific accumulation in either or both genotypes. Detailed bioinformatic analyses of differentially expressed proteins (DEPs) from the large- and small-grain wheat cultivars underscored the developmental differences observed between them and shed light on the molecular and cellular processes contributing to these differences. In silico localization of either or both sets of DEPs to wheat chromosomes exhibited a biased genomic distribution with chromosome 4D contributing largely to it. These results corresponded well with the earlier studies, performed in common wheat, where chromosome 4D was reported to harbor QTLs for yield contributing traits specifically grain length. Collectively, our results provide insight into the molecular processes taking place during early grain development, a knowledge, which may prove useful in improving wheat grain yield in the future

Programmed chloroplast destruction during leaf senescence involves 13-lipoxygenase (13-LOX)

Mammals including humans use highly specific pathways for tissue differentiation. One such pathway is operative in reticulocytes and involves the programmed destruction of the cell?s organellar complement by 15-lipoxygenase (15-LOX), which oxygenates polyunsaturated membrane fatty acids and provokes organelle leakage. As we report here, plants make use of a similar LOX pathway to degrade their chloroplasts during leaf senescence. The enzyme involved is a 13-LOX with unique positional specificity and molecular terms. Because 15-LOX and 13-LOX pathway products likewise operate in biological defense, a mechanism of cross-kingdom conservation of pathway regulation and function was uncovered for multicellular eukaryotes

Lipid modulation contributes to heat stress adaptation in peanut

At the cellular level, membrane damage is a fundamental cause of yield loss at high temperatures (HT). We report our investigations on a subset of a peanut (Arachis hypogaea) recombinant inbred line population, demonstrating that the membrane lipid remodeling occurring at HT is consistent with homeoviscous adaptation to maintain membrane fluidity. A major alteration in the leaf lipidome at HT was the reduction in the unsaturation levels, primarily through reductions of 18:3 fatty acid chains, of the plastidic and extra-plastidic diacyl membrane lipids. In contrast, levels of 18:3-containing triacylglycerols (TGs) increased at HT, consistent with a role for TGs in sequestering fatty acids when membrane lipids undergo remodeling during plant stress. Polyunsaturated acyl chains from membrane diacyl lipids were also sequestered as sterol esters (SEs). The removal of 18:3 chains from the membrane lipids decreased the availability of susceptible molecules for oxidation, thereby minimizing oxidative damage in membranes. Our results suggest that transferring 18:3 chains from membrane diacyl lipids to TGs and SEs is a key feature of lipid remodeling for HT adaptation in peanut. Finally, QTL-seq allowed the identification of a genomic region associated with heat-adaptive lipid remodeling, which would be useful for identifying molecular markers for heat tolerance

Mass Spectrometry: An Essential Tool for Genome and Proteome Analysis

48-64Mass spectrometry (MS), in its various forms, has become an essential tool for genome and proteome analysis. It involves gaseous ionization of the analyte to be examined, followed by separation of ions according to mass-to-charge (mlz) ratio and determination of molecular masses of iOIlSfrom mass spectra obtained after mass spectrometry of analyte. Several methods for ionization, mainly including MALDI and ES, each coupled with a specific mass spectral analysis system (e.g. TOF-MS and quadrupole MS) are available. MS/MS is devised particularly for the determination of amino acid sequences of small peptide. The advantage of MS over other techniques is its speed, since gel electrophoresis and labeling of the analyte, needed in other techniques used for genome/proteome analysis, can be dispensed with. Applications of mass spectrometry for genome analysis include DNA sequencing and SNP detection, the latter involving PinPoint assay (minisequencing), PNA hybridization, invader cleavage, "MALDI on a chip", etc. Similarly, its applications for proteome analysis include peptide sequencing, determination of molecular weights of proteins and protein identification by database search. Protein modifications and protein-protein interactions can also be examined by coupling mass spectrometry with database search. In this manner, mass spectrometry has become an essential tool for genome and proteome analysis

Mass spectrometry: an essential tool for genome and proteome analysis

Mass spectrometry (MS), in its various forms, has become an essential tool for genome and proteome analysis. It involves gaseous ionization of the analyte to be examined, followed by separation of ions according to mass-to-charge (mlz) ratio and determination of molecular masses of iOIlSfrom mass spectra obtained after mass spectrometry of analyte. Several methods for ionization, mainly including MALDI and ES, each coupled with a specific mass spectral analysis system (e.g. TOF-MS and quadrupole MS) are available. MS/MS is devised particularly for the determination of amino acid sequences of small peptide. The advantage of MS over other techniques is its speed, since gel electrophoresis and labeling of the analyte, needed in other techniques used for genome/proteome analysis, can be dispensed with. Applications of mass spectrometry for genome analysis include DNA sequencing and SNP detection, the latter involving PinPoint assay (minisequencing), PNA hybridization, invader cleavage, "MALDI on a chip", etc. Similarly, its applications for proteome analysis include peptide sequencing, determination of molecular weights of proteins and protein identification by database search. Protein modifications and protein-protein interactions can also be examined by coupling mass spectrometry with database search. In this manner, mass spectrometry has become an essential tool for genome and proteome analysis

Genetic and molecular basis of grain size and grain number and its relevance to grain productivity in higher plants

Grain size and grain number constitute 2 important components of grain yield. In particular, the grain size also influences the end-use quality (e.g., flour yield and protein content) and attracts consumer preference. These 2 traits are also the components of the domestication syndrome of crop plants. A number of important studies have recently been conducted to understand the genetic and molecular basis of these 2 important yield-contributing traits. Information generated from these studies was collected and synthesized for the benefit of plant biologists, particularly plant breeders. In the present article, this information is briefly reviewed and the prospects of using this information for improvement of grain productivity in crop plants are discussed