In Vitro Synthesis of Wheat (Triticum aestivum L.) Storage Proteins

Free and membrane-associated polysomes were isolated in approximately equal amounts from endosperm of wheat kernels harvested 20 days after anthesis. The presence of heparin in the homogenizing buffer minimized polysome degradation. Ribonucleic acid from the isolated polysomes, when translated in vitro in a wheat germ system, yielded products ranging in size from about 12,000 to about 80,000 daltons, including at least two polypeptides that co-migrated with seed extract proteins in sodium dodecyl sulfate polyacrylamide gel electrophoresis. The nature of the translation products of free and membrane-associated RNA are distinctly different, with membrane-associated RNA yielding a higher proportion of polypeptides in the size range of 30,000 to 37,000 daltons. Analysis of membrane-associated 3′-terminal polyadenylyl-containing RNA in vitro translation products, by solubility in 70% ethanol and by immunoprecipitation, indicates that the 33,000- to 37,000-dalton polypeptides contain gliadins, and the analysis provides evidence that these proteins are synthesized in association with membranous cell organelles. Gliadin polypeptides synthesized in vitro are larger than authentic gliadins and probably are precursors which, in vivo, undergo modification to yield the smaller final products.     

Trehalose Biosynthesis in Response to Abiotic Stresses

Trehalose is a non‐reducing disaccharide that is present in diverse organisms ranging from bacteria and fungi to invertebrates, in which it serves as an energy source, osmolyte or protein/membrane protectant. The occurrence of trehalose and trehalose biosynthesis pathway in plants has been discovered recently. Multiple studies have revealed regulatory roles of trehalose‐6‐phosphate, a precursor of trehalose, in sugar metabolism, growth and development in plants. Trehalose levels are generally quite low in plants but may alter in response to environmental stresses. Transgenic plants overexpressing microbial trehalose biosynthesis genes have been shown to contain increased levels of trehalose and display drought, salt and cold tolerance. In‐silico expression profiling of all Arabidopsis trehalose‐6‐phosphate synthases (TPSs) and trehalose‐6‐phosphate phosphatases (TPPs) revealed that certain classes of TPS and TPP genes are differentially regulated in response to a variety of abiotic stresses. These studies point to the importance of trehalose biosynthesis in stress responses.     

Competition Increases Sensitivity of Wheat (Triticum aestivum) to Biotic Plant-Soil Feedback

Plant-soil feedback (PSF) and plant competition play an important role in structuring vegetation composition, but their interaction remains unclear. Recent studies suggest that competing plants could dilute pathogenic effects, whereas the standing view is that competition may increase the sensitivity of the focal plant to PSF. In agro-ecosystems each of these two options would yield contrasting outcomes: reduced versus enhanced effects of weeds on crop biomass production. To test the effect of competition on sensitivity to PSF, we grew Triticum aestivum (Common wheat) with and without competition from a weed community composed of Vicia villosa, Chenopodium album and Myosotis arvensis. Plants were grown in sterilized soil, with or without living field inoculum from 4 farms in the UK. In the conditioning phase, field inocula had both positive and negative effects on T. aestivum shoot biomass, depending on farm. In the feedback phase the differences between shoot biomass in T. aestivum monoculture on non-inoculated and inoculated soils had mostly disappeared. However, T. aestivum plants growing in mixtures in the feedback phase were larger on non-inoculated soil than on inoculated soil. Hence, T. aestivum was more sensitive to competition when the field soil biota was present. This was supported by the statistically significant negative correlation between shoot biomass of weeds and T. aestivum, which was absent on sterilized soil. In conclusion, competition in cereal crop-weed systems appears to increase cereal crop sensitivity to soil biota.     

Response of Spring Wheat (Triticum aestivum L.) Quality Traits and Yield to Sowing Date

The unpredictability and large fluctuation of the climatic conditions in rainfed regions do affect spring wheat yield and grain quality. These variations offer the opportunity for the production of better quality wheat. The effect of variable years, locations and sowing managements on wheat grain yield and quality was studied through field experiments using three genotypes, three locations for two years under rainfed conditions. The two studied years as contrasting years at three locations and sowing dates depicted variability in temperature and water stress during grain filling which resulted considerable change in grain yield and quality. Delayed sowing, years (2009–10) and location (Talagang) with high temperature and water stress resulted increased proline, and grain quality traits i.e. grain protein (GP) and grain ash (GA) than optimum conditions (during 2008–09, at Islamabad and early sowing). However, opposite trend was observed for dry gluten (DG), sodium dodecyl sulphate (SDS), SPAD content and grain yield irrespective of genotypes. The influence of variable climatic conditions was dominant in determining the quality traits and inverse relationship was observed among some quality traits and grain yield. It may be concluded that by selecting suitable locations and different sowing managements for subjecting the crop to desirable environmental conditions (temperature and water) quality traits of wheat crop could be modified.     

The Vascular System of the Spikelet in Wheat (Triticum aestivum)

The lower three florets in a spikelet of wheat cv. Aotea werefound to be supplied by the principal vascular bundles of therachilla, while the system of more distal florets consistedof subvascular elements derived from the vascular cylinder formedat the disc of insertion of these florets. This pattern appearedto be the same in all spikelets irrespective of position, apartfrom the terminal one, nor was it altered by raising the supplyof nitrogen. The apparent constancy of the vascular system iscontrasted with considerable variability in the number of grain-bearingflorets depending on genotype and environment. If a floret isconnected directly with the main vascular system and if assimilatesare not limiting, then competition for assimilates does notappear to be the main factor preventing grain formation.     

Genome-Wide Identification and Characterization of Germin and Germin-Like Proteins (GLPs) and Their Response Under Powdery Mildew Stress in Wheat (Triticum aestivum L.)

Plant Molecular Biology Reporter - Germin and germin-like proteins (GLPs) play multifaceted roles in plants and participate in signaling processes associated with host–pathogen interactions...     

Two-Dimensional Electrophoretic Analysis of Soluble Leaf Proteins of a Salt-sensitive （Triticum aestivum） and a Salt-tolerant （T. durum） Cultivar in Response to NaCI Stress

In this research, 3-day-old etiolated wheat seedlings of Triticum aestivum L. cv. Ceyhan-99 （salt-sensitive） and T. durum Desf. cv. Firat-93 （salt-tolerant） were grown in control and salt （150 mmol/L NaCl） treatments at a 15/25℃ temperature regime in the light for 12 days. Soluble proteins extracted from the first leaf tissues of two cultivars were analyzed by twodimensional （2-D） electrophoresis in order to detect NaCl-induced changes. The soluble leaf protein profiles of cultivars were observed to be similar. However, quantitative differences in 74 proteins were detected in the salt treatment group, compared to the control. Among the 74 protein spots, 14 were common for two cultivars. As a result of NaCl treatment, two low-molecular-weight （LMW） proteins （28.9 and 30.0 kDa） and one intermediate-molecular-weight （IMW） protein （44.3 kDa） in cv. Ceyhan-99 and six LMW proteins （18.6, 19.4, 25.7, 25.9, 26 and 27.6 kDa） in cv. Firat-93 were newly synthesized. The newly synthesized proteins were specific to each cultivar. In the Firat-93 cultivar, four proteins with LMW （24.8-27.9 kDa） were completely lost in NaCl treatment. Moreover, these four protein spots were not observed in both protein profiles of cv. Ceyhan-99. Most of these proteins were in acidic character （pl 〈6.0-6.9） and low molecular weight （〈31.6 kDa）. It is suggested that the newly synthesized or completely lost LMW proteins may be important for cultivars differing in sensitivity towards NaCl.     

Two-Dimensional Electrophoretic Analysis of Soluble Leaf Proteins of a Salt-sensitive(Triticum aestivum)and a Salt-tolerant(T.durum)Cultivar in Response to NaCl Stress

In this research, 3-day-old etiolated wheat seedlings of Triticum aestivum L. cv. Ceyhan-99 (salt-sensitive) and T. durumDesf. cv. Firat-93 (salt-tolerant) were grown in control and salt (150 mmol/L NaCI) treatments at a 15/25℃ temperatureregime in the light for 12 days. Soluble proteins extracted from the first leaf tissues of two cultivars were analyzed by two-dimensional (2-D) electrophoresis in order to detect NaCl-induced changes. The soluble leaf protein profiles of cultivarswere observed to be similar. However, quantitative differences in 74 proteins were detected in the salt treatment group,compared to the control. Among the 74 protein spots, 14 were common for two cultivars. As a result of NaCl treatment, twolow-molecular-weight (LMW) proteins (28.9 and 30.0 kDa) and one intermediate-molecular-weight (IMW) protein (44.3 kDa)in cv. Ceyhan-99 and six LMW proteins (18.6, 19.4, 25.7, 25.9, 26 and 27.6 kDa) in cv. Firat-93 were newly synthesized. Thenewly synthesized proteins were specific to each cultivar. In the Firat-93 cultivar, four proteins with LMW (24.8-27.9 kDa)were completely lost in NaCl treatment. Moreover, these four protein spots were not observed in both protein profiles ofcv. Ceyhan-99. Most of these proteins were in acidic character (pi<6.0-6.9) and low molecular weight (<31.6 kDa). It issuggested that the newly synthesized or completely lost LMW proteins may be important for cultivars differing in sensitivitytowards NaCl.     

Developmental Base Temperature in Different Phenological Phases of Wheat (Triticum aestivum)

The linear relationship between temperature and developmentrate has been widely recognized and it has been suggested thatthermal units (the summation of daily mean temperature abovea base temperature) can predict the phenological developmentof a crop. The aim of this paper was to determine the base temperaturefor different phenological phases of wheat. Two mediterraneanwheat cultivars and five sowing dates were used to obtain differentmean temperatures during development and different developmentalrates. The linear regression of development rate against meantemperatures for each period indicated that there were no uniquebase temperatures for all stages of the life span and valuesclose to 4°C and to 9·5°C were found to be bestfits for base temperatures before and after the terminal spikeletstage of both cultivars. A model to predict wheat developmentwas validated with another data set, which included differentwheat cultivars and sowing dates. Estimates of the error indevelopmental prediction by using a single base temperatureof 0°C is discussed as a function of separate developmentstages. Key words: Wheat development, base temperature, thermal time, Triticum aestivum     

禾本科植物响应非生物胁迫的转录调控网络

分子和遗传研究表明,转录因子在响应非生物胁迫的基因表达调控中起着重要的作用,并且大部分转录因子在禾本科植物和拟南芥中是相同的.禾本科植物包括许多重要的农作物,对禾本科植物的转录因子进行研究,可增强重要农作物对非生物胁迫的耐受性.综述了禾本科植物响应非生物胁迫的转录调控网络,包括响应寒冷胁迫的DREB1/CBF调节子、响应脱水和高盐胁迫的DREB2调节子,ABA介导反应的ABRE及其伴侣元件、响应ABA的AREB/ABF调节子,响应脱水、高盐和寒冷胁迫的NAC调节子.     

Mineral Ion Transport in the Embryos of Germinating Wheat (Triticum aestivum)

The germinating wheat embryo contains two mineral ion pumps.One is a H⁺/K⁺ antiport system located in the scutellum andthe other is a H⁺/anion symport, or possibly an anion/OH⁺ antiportsystem located in the embryo axis. The scutellum pump closelyresembles that found in other plant tissues; its affinity constantfor K⁺ is about 0.03 mM and its activity is energy dependentThe embryo axis pump is able to transport K⁺ in place of H⁺and appears to be a general monovalent cation/anion symportsystem. The scutellum pumping activity is stimulated by GA and the GAaction is inhibited by ABA. GA stimulates H⁺ more than K⁺ transport,electrochemical neutrality always being maintained by aniontransport. In contrast to reports about IAA-stimulated ion transportin other plant tissues, there is no evidence that the GA actionin the scutellum is dependent upon active protein synthesis.     

Free Polyamines in Senescing Wheat(Triticum aestivum L.)

The free polyamine content of flag leaves, peduncles, rachis,glumes, and grains of wheat (Triticum aestivum L., cv. Castell)plants, ripening under field conditions, has been investigatedduring three consecutive growing seasons. Putrescine was quantitativelythe most important of all polyamines detected in these organs.Concentrations were highest in the grains, glumes and flag leaves.No correlation was found between polyamine content and the onsetof senescence of flag leaves and other organs. Excised primaryleaves, however, showed a decrease in polyamine content in thedark and also in light/dark cycles, but in the latter case onlyafter an initial increase. Sink removal of otherwise intactwheat plants caused an accumulation of putrescine in flag leavesat the later stages of senescence, whereas removal of all otherleaves was without any significant effect. Putrescine was alsorecovered in phloem-exudate samples collected throughout theperiod of grain development. In both grains and glumes, peakconcentrations of polyamines were found early during seed development. Key words: Triticum aestivum, polyamines, ripening, senescence     

Identification and Evolution of FYVE Domain-Containing Proteins and Their Expression Patterns in Response to Abiotic Stresses in Rice

The FYVE domain is a typical zinc finger motif containing four conserved CxxC pairs and has been shown to specifically binds to PtdIns(3)P on the surface of cell membrane. FYVE domain-containing proteins are commonly distributed in eukaryotic cells and have been implicated in diverse functions like signal transduction, membrane trafficking, exocytosis and endocytosis, phosphoinositides (PIs) metabolism, and cytoskeletal regulation. Analysis of the rice genome using comprehensive online databases and research tools resulted in the identification of 19 putative rice FYVE (OsFVYE) proteins. Based on domain architectural and phylogenetic analyses, these OsFYVEs were further classified into six groups. Groups I–V were conserved in Arabidopsis (dicots) and rice (monocot) at both the genetic and protein levels, while group VI was widely present in plants but truncated in Arabidopsis and species of Brassicaceae. Comprehensive and comparative investigation of their expression profiles showed that FYVE genes in plant exhibited a variety of expression patterns during different developmental stages and in response to phytohormones and abiotic stresses. These findings indicated that both OsFYVE and AtFYVE genes may played potential roles in normal plant growth, hormone signal transduction, and abiotic stress tolerance. Results from our study shed light on the potential roles of FYVE proteins in plant growth, development, and stress responses.     

Identification of Kernel Proteins Associated with the Resistance to Fusarium Head Blight in Winter Wheat (Triticum aestivum L.)

Numerous potential components involved in the resistance to Fusarium head blight (FHB) in cereals have been indicated, however, our knowledge regarding this process is still limited and further work is required. Two winter wheat (Triticum aestivum L.) lines differing in their levels of resistance to FHB were analyzed to identify the most crucial proteins associated with resistance in this species. The presented work involved analysis of protein abundance in the kernel bulks of more resistant and more susceptible wheat lines using two-dimensional gel electrophoresis and mass spectrometry identification of proteins, which were differentially accumulated between the analyzed lines, after inoculation with F. culmorum under field conditions. All the obtained two-dimensional patterns were demonstrated to be well-resolved protein maps of kernel proteomes. Although, 11 proteins were shown to have significantly different abundance between these two groups of plants, only two are likely to be crucial and have a potential role in resistance to FHB. Monomeric alpha-amylase and dimeric alpha-amylase inhibitors, both highly accumulated in the more resistant line, after inoculation and in the control conditions. Fusarium pathogens can use hydrolytic enzymes, including amylases to colonize kernels and acquire nitrogen and carbon from the endosperm and we suggest that the inhibition of pathogen amylase activity could be one of the most crucial mechanisms to prevent infection progress in the analyzed wheat line with a higher resistance. Alpha-amylase activity assays confirmed this suggestion as it revealed the highest level of enzyme activity, after F. culmorum infection, in the line more susceptible to FHB.     

Novel Structural and Functional Motifs in cellulose synthase (CesA) Genes of Bread Wheat (Triticum aestivum,L.)

Cellulose is the primary determinant of mechanical strength in plant tissues. Late-season lodging is inversely related to the amount of cellulose in a unit length of the stem. Wheat is the most widely grown of all the crops globally, yet information on its CesA gene family is limited. We have identified 22 CesA genes from bread wheat, which include homoeologs from each of the three genomes, and named them as TaCesAXA, TaCesAXB or TaCesAXD, where X denotes the gene number and the last suffix stands for the respective genome. Sequence analyses of the CESA proteins from wheat and their orthologs from barley, maize, rice, and several dicot species (Arabidopsis, beet, cotton, poplar, potato, rose gum and soybean) revealed motifs unique to monocots (Poales) or dicots. Novel structural motifs CQIC and SVICEXWFA were identified, which distinguished the CESAs involved in the formation of primary and secondary cell wall (PCW and SCW) in all the species. We also identified several new motifs specific to monocots or dicots. The conserved motifs identified in this study possibly play functional roles specific to PCW or SCW formation. The new insights from this study advance our knowledge about the structure, function and evolution of the CesA family in plants in general and wheat in particular. This information will be useful in improving culm strength to reduce lodging or alter wall composition to improve biofuel production.     

Zinc (Zn)-phosphorus (P) Interactions in Two Cultivars of Spring Wheat (Triticum aestivum L.) Differing in P Uptake Efficiency

Zinc-phosphorus (Zn-P) interactions were investigated in twowheat cultivars (Brookton and Krichauff) differing in P uptakeefficiency. The experiment was carried out in a growth chamber.Rock phosphate or CaHPO₄were used as P sources, and ammoniumnitrate or nitrate only as nitrogen sources. Two Zn levels wereused: 0.22 and 2.2 mg ZnSO₄.5H₂O kg^-1. The results confirmedthat Brookton had a higher P uptake efficiency than Krichauffunder low P conditions, irrespective of nitrogen and Zn supply.Zn supply had little effect on tissue P concentration and Puptake per unit of root weight in either cultivar, irrespectiveof nitrogen supply. An increase in P availability caused a significantreduction in Zn uptake per unit of root weight, and tissue concentrationof Zn in both cultivars. The reduction in tissue Zn concentrationcannot be explained entirely by a dilution effect. Zn uptakeby, and Zn concentrations in, Brookton (with high P uptake efficiency)were significantly lower than those of Krichauff. Zn concentrationsin Brookton were more sensitive to P uptake than those in Krichauff.It is suggested that high P uptake efficiency may depress plantuptake of Zn, and therefore cause a reduction in the concentration(density) of Zn in grains of wheats grown in low P (and possiblylow Zn) soils. Copyright 2001 Annals of Botany Company Phosphorus efficiency, translocation, uptake, zinc-phosphorus interaction, wheat