Assessment of salinity indices to identify Iranian wheat varieties using an artificial neural network

In arid and semi‐arid regions of the world, including Iran, soil salinity is one of the major abiotic stresses. One of the ways to achieve high performance in these areas is to use salt‐tolerant varieties of wheat. Iran is known as one of the places where the D‐genome originated and evolved. In order to evaluate the salt tolerance of Iranian genotypes based on the eight indices using analysis of variance, regression and an artificial neural network (ANN), 41 Iranian wheat varieties (Trticum aestivum L.) were planted in a randomised complete block design with three replications under two saline irrigation conditions, 0.631 and 11.8 dS m^?1, in Kerman, Iran. Significant differences between the varieties were observed, and the significant two‐way interaction of environment × varieties in combined analysis and non‐significant correlation, 0.07, between the yield in two environments (yield in non‐stress conditions, Yp, and yield in stress conditions, Ys) indicates the existence of genetic variation among varieties and the different responses of the varieties in both the environments. The indices of tolerance, geometric mean product (GMP), mean product (MP), harmonic mean (HM) and stress tolerance index (STI) were calculated based on grain yield evidence of positive significant correlation with Yp and Ys. Based on the ANN results, yield stability index (YSI), MP, GMP and STI were the best indices to predict salinity‐tolerant varieties. The varieties selected based on these indices, such as Bolani, Sistan, Ofogh, Pishtaz, Karchia and Arg, produced high yield in both the environments. These results show that bread wheat originating from Iran has salt tolerance potential and can also be used in studies related to salinity tolerance mechanisms.     

Quantitative trait loci (QTL) mapping for physiological and biochemical attributes in a Pasban90/Frontana recombinant inbred lines (RILs) population of wheat (Triticum aestivum) under salt stress condition

Salt stress causes nutritional imbalance and ion toxicity which affects wheat growth and production. A population of recombinant inbred lines (RILs) were developed by crossing Pasban90 (salt tolerant) and Frontana (salt suceptible) for identification of quantitative trait loci (QTLs) for physiological traits including relative water content, membrane stability index, water potential, osmotic potential, total chlorophyll content, chlorophyll a, chlorophyll b and biochemical traits including proline contents, superoxide dismutase, sodium content, potassium content, chloride content and sodium/potassium ratio by tagging 202 polymorphic simple sequence repeats (SSR) markers. Linkage map of RILs comprised of 21 linkage group covering A, B and D genome for tagging and maped a total of 60 QTLs with major and minor effect. B genome contributed to the highest number of QTLs under salt stress condition. Xgwm70 and Xbarc361 mapped on chromosome 6B was linked with Total chlorophyll, water potential and sodium content. The increasing allele for all these QTLs were advanced from parent Pasban90. Current study showed that Genome B and D had more potentially active genes conferring plant tolerance against salinity stress which may be exploited for marker assisted selection to breed salinity tolerant high yielding wheat varieties.     

Proteomic analysis of wheat embryos with 2-DE and liquid-phase chromatography (ProteomeLab PF-2D) — A wider perspective of the proteome

Cereal embryos are a model system to study desiccation tolerance due to their ability to survive extreme water loss during late embryogenesis. To identify proteins accumulating in mature embryos which can be used as potential markers for dehydration tolerance, we compared the embryo proteome from two durum wheat genotypes (Triticum durum Desf.), Mahmoudi (salt and drought sensitive) and Om Rabia3 (salt and drought tolerant). Total protein extracts from wheat embryos were analyzed by using conventional 2-DE and ProteomeLab PF-2D. Analysis using different pH ranges showed that a larger number of fractions were solved by LC, than by conventional 2-DE at extreme technical pHs (pH 4.0–5.0 and pH 6.5–8.0). In contrast, at intermediate pHs (pH 5.0–6.5), resolution was better in 2-DE gels. The two techniques were used in parallel to analyze total protein extracts from embryos of the two wheat varieties. Several proteins belonging to the seed storage family, LEA-type/heat shock proteins, enzyme metabolism and radical scavengers were identified by analysis of trypsin digested peptides via mass spectrometry. These proteins accumulate in different amounts in embryos of tolerant and sensitive wheat varieties. The differences in expression pattern were further validated by enzyme activity, western blotting analysis and correlated with their corresponding mRNA expression by RT-PCR analyses for the corresponding protein. We suggest that the differential expression pattern could be used as a basis for a biochemical screen of tolerance/sensitivity to drought and salt stress in wheat embryos and germplasm.     

TaCYP81D5, one member in a wheat cytochrome P450 gene cluster,confers salinity tolerance via reactive oxygen species scavenging

As one of the largest gene families in plants, the cytochrome P450 monooxygenase genes (CYPs) are involved in diverse biological processes including biotic and abiotic stress response. Moreover, P450 genes are prone to expanding due to gene tandem duplication during evolution, resulting in generations of novel alleles with the neo‐function or enhanced function. Here, the bread wheat (Triticum aestivum) gene TaCYP81D5 was found to lie within a cluster of five tandemly arranged CYP81D genes, although only a single such gene (BdCYP81D1) was present in the equivalent genomic region of the wheat relative Brachypodium distachyon. The imposition of salinity stress could up‐regulate TaCYP81D5, but the effect was abolished in plants treated with an inhibitor of reactive oxygen species synthesis. In SR3, a wheat cultivar with an elevated ROS content, the higher expression and the rapider response to salinity of TaCYP81D5 were related to the chromatin modification. Constitutively expressing TaCYP81D5 enhanced the salinity tolerance both at seedling and reproductive stages of wheat via accelerating ROS scavenging. Moreover, an important component of ROS signal transduction, Zat12, was proven crucial in this process. Though knockout of solely TaCYP81D5 showed no effect on salinity tolerance, knockdown of BdCYP81D1 or all TaCYP81D members in the cluster caused the sensitivity to salt stress. Our results provide the direct evidence that TaCYP81D5 confers salinity tolerance in bread wheat and this gene is prospective for crop improvement.     

Plasma membrane proteome analysis identifies a role of barley membrane steroid binding protein in root architecture response to salinity

Although the physiological consequences of plant growth under saline conditions have been well described, understanding the core mechanisms conferring plant salt adaptation has only started. We target the root plasma membrane proteomes of two barley varieties, cvs. Steptoe and Morex, with contrasting salinity tolerance. In total, 588 plasma membrane proteins were identified by mass spectrometry, of which 182 were either cultivar or salinity stress responsive. Three candidate proteins with increased abundance in the tolerant cv. Morex were involved either in sterol binding (a GTPase‐activating protein for the adenosine diphosphate ribosylation factor [ZIGA2], and a membrane steroid binding protein [MSBP]) or in phospholipid synthesis (phosphoethanolamine methyltransferase [PEAMT]). Overexpression of barley MSBP conferred salinity tolerance to yeast cells, whereas the knock‐out of the heterologous AtMSBP1 increased salt sensitivity in Arabidopsis. Atmsbp1 plants showed a reduced number of lateral roots under salinity, and root‐tip‐specific expression of barley MSBP in Atmsbp1 complemented this phenotype. In barley, an increased abundance of MSBP correlates with reduced root length and lateral root formation as well as increased levels of auxin under salinity being stronger in the tolerant cv. Morex. Hence, we concluded the involvement of MSBP in phytohormone‐directed adaptation of root architecture in response to salinity.     

Proteome analysis of an ectomycorrhizal fungus Boletus edulis under salt shock

Soil salinization has become a severe global problem and salinity is one of the most severe abiotic stresses inhibiting growth and survival of mycorrhizal fungi and their host plants. Salinity tolerance of ectomycorrhizal fungi and survival of ectomycorrhizal inocula is essential to reforestation and ecosystem restoration in saline areas. Proteomic changes of an ectomycorrhizal fungus, Boletus edulis, when exposed to salt stress conditions (4 % NaCl, w/v) were determined using two-dimensional electrophoresis (2DE) and mass spectrometry (MS) techniques. Twenty-two protein spots, 14 upregulated and 8 downregulated, were found changed under salt stress conditions. Sixteen changed protein spots were identified by nanospray ESI Q-TOF MS/MS and liquid chromatography MS/MS. These proteins were involved in biosynthesis of methionine and S-adenosylmethionine, glycolysis, DNA repair, cell cycle control, and general stress tolerance, and their possible functions in salinity adaptation ofBoletus edulis were discussed.     

小麦品种资源耐盐性鉴定

按照农业部行业标准NY/PZT001-2002,对882份小麦品种资源进行耐盐性初步鉴定,筛选出芽期耐盐性为一级的品种328份,苗期和芽期都达到中度耐盐的品种43份。这些品种中很多既具有中度或中度以上耐盐性且具有高产优质等优异特性,如小偃22、新曙光1号等,为小麦耐盐育种提供重要信息。相关分析表明,不同耐盐级别的小麦品种其芽期和苗期耐盐性并没有一致的相关关系,二者并没有可比性,在耐盐种质筛选过程中,都有其本身的意义。     

Sub-proteome differential display: single gel comparison by 2D electrophoresis and mass spectrometry

Two-dimensional (2D) gel electrophoresis and mass spectrometry (MS) have been used in comparative proteomics but inherent problems of the 2D electrophoresis technique lead to difficulties when comparing two samples. We describe a method (sub-proteome differential display) for comparing the proteins from two sources simultaneously. Proteins from one source are mixed with radiolabelled proteins from a second source in a ratio of 100:1. These combined proteomes are fractionated simultaneously using column chromatographic methods, followed by analysis of the pre-fractionated proteomes (designated sub-proteomes) using 2D gel electrophoresis. Silver staining and (35)S autoradiography of a single gel allows precise discrimination between members of each sub-proteome, using commonly available computer software. This is followed by MS identification of individual proteins. We have demonstrated the utility of the technology by identifying the product of a transfected gene and several proteins expressed differentially between two renal carcinoma proteomes. The procedure has the capacity to enrich proteins prior to 2D electrophoresis and provides a simple, inexpensive approach to compare proteomes. The single gel approach eliminates differences that might arise if separate proteome fractionations or 2D gels are employed.     

Analysis of the grasspea proteome and identification of stress-responsive proteins upon exposure to high salinity, low temperature, and abscisic acid treatment

Abiotic stress causes diverse biochemical and physiological changes in plants and limits crop productivity. Plants respond and adapt to such stress by altering their cellular metabolism and activating various defense machineries. To understand the molecular basis of stress tolerance in plants, we have developed differential proteomes in a hardy legume, grasspea (Lathyrus sativus L.). Five-week-old grasspea seedlings were subjected independently to high salinity, low temperature and abscisic acid treatment for duration of 36 h. The physiological changes of stressed seedlings were monitored, and correlated with the temporal changes of proteome using two-dimensional gel electrophoresis. Approximately, 400 protein spots were detected in each of the stress proteome with one-fourth showing more than 2-fold differences in expression values. Eighty such proteins were subjected to LC-tandem MS/MS analyses that led to the identification of 48 stress-responsive proteins (SRPs) presumably involved in a variety of functions, including metabolism, signal transduction, protein biogenesis and degradation, and cell defense and rescue. While 33 proteins were responsive to all three treatments, 15 proteins were expressed in stress-specific manner. Further, we explored the possible role of ROS in triggering the stress-induced degradation of large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase (Rubisco). These results might help in understanding the spectrum of stress-regulated proteins and the biological processes they control as well as having implications for strategies to improve stress adaptation in plants.     

CO2／盐冲击对小麦幼苗呼吸酶活性的影响

以不同抗盐小麦 (Triticum aestivum L.)为材料 ,研究了 CO2 /盐冲击对幼苗生长状况、叶绿素含量、光呼吸和三羧酸循环 (TCAC)关键酶活性的影响。结果表明 :Na Cl抑制小麦生长 ,而 CO2 促进生长 ,这种效应盐处理植株比非盐处理植株明显 ;Na Cl降低叶绿素含量 ,CO2 可使其轻微提高 ;盐对普通小麦TCAC中的异柠檬酸脱氢酶 (IDH)、琥珀酸脱氢酶 (SDH)、苹果酸脱氢酶 (MDH)和光呼吸中的乙醇酸氧化酶 (GO)、羟基丙酮酸还原酶 (HPR)有刺激作用 ,CO2 则抑制它们的活性。抗盐小麦对 CO2 /盐冲击的反应与普通小麦有差别。结果可以说明 ,CO2 能够减轻 Na Cl对植物的毒害效应     

小麦芽期和苗期耐盐性综合评价

土壤盐渍化严重影响小麦生产,提高小麦耐盐性是应对土壤盐渍化的主要途径之一,耐盐种质资源是耐盐性遗传改良的材料基础。本研究以小麦为材料,筛选芽期和苗期耐盐性鉴定评价的适宜Na Cl浓度,明确了小麦芽期耐盐性鉴定的最适Na Cl溶液浓度为1.2%,苗期耐盐性鉴定的最适土壤Na Cl浓度为0.8%。用该盐浓度胁迫处理321份小麦材料,获得芽期高耐盐材料21份,占供试材料的6.5%;苗期高耐盐材料18份,占供试材料的5.6%;芽期和苗期均为高耐盐的材料2份,分别是中作60115和冀麦一号。     

Identification of proteins associated with ion homeostasis and salt tolerance in barley

Identification and characterization of proteins involved in salt tolerance are imperative for revealing its genetic mechanisms. In this study, ionic and proteomic responses of a Tibetan wild barley XZ16 and a well‐known salt‐tolerant barley cv. CM72 were analyzed using inductively coupled plasma‐optical emission spectrometer, 2DE, and MALDI‐TOF/TOF MS techniques to determine salt‐induced differences in element and protein profiles between the two genotypes. In total, 41 differentially expressed proteins were identified in roots and leaves, and they were associated with ion homeostasis, cell redox homeostasis, metabolic process, and photosynthesis. Under salinity stress, calmodulin, Na/K transporters, and H⁺‐ATPases were involved in establishment of ion homeostasis for barley plants. Moreover, ribulose‐1,5‐bisphosphate carboxylase/oxygenase activase and oxygen‐evolving enhancer proteins were significantly upregulated under salinity stress, indicating the great impact of salinity on photosynthesis. In comparison with CM72, XZ16 had greater relative dry weight and lower Na accumulation in the shoots under salinity stress. A higher expression of HvNHX1 in the roots, and some specific proteins responsible for ion homeostasis and cell redox homeostasis, was also found in XZ16 exposed to salt stress. The current results showed that Tibetan wild barley XZ16 and cultivated barley cultivar CM72 differ in the mechanism of salt tolerance.     

Two‐dimensional proteome reference maps for the human pathogenic filamentous fungus Aspergillus fumigatus

The filamentous fungus Aspergillus fumigatus has become the most important airborne fungal pathogen causing life‐threatening infections in immunosuppressed patients. We established a 2‐D reference map for A. fumigatus. Using MALDI‐TOF‐MS/MS, we identified 381 spots representing 334 proteins. Proteins involved in cellular metabolism, protein synthesis, transport processes and cell cycle were most abundant. Furthermore, we established a protocol for the isolation of mitochondria of A. fumigatus and developed a mitochondrial proteome reference map. 147 proteins represented by 234 spots were identified.     

Novel clues on abiotic stress tolerance emerge from embryo proteome analyses of rice varieties with contrasting stress adaptation

Cereal embryos sustain severe water deficit at the final stage of seed maturation. The molecular mechanisms underlying the acquisition of desiccation tolerance in seed embryos are similar to those displayed during water deficit in vegetative tissues. The genetic variation among six rice genotypes adapted to diverse environmental conditions was analysed at the proteome level to get further clues on the mechanisms leading to water-stress tolerance. MS analysis allowed the identification of 28 proteins involved in stress tolerance (late embryogenesis abundant proteins), nutrient reservoir activity, among other proteins implicated in diverse cellular processes potentially related to the stress response (e.g., mitochondrial import translocase). Hierarchical clustering and multidimensional scaling analyses revealed a close relationship between the stress-sensitive genotypes, whereas the stress-tolerant varieties were more distantly related. Besides qualitative and significant quantitative changes in embryo proteins across the distinct varieties, we also found differences at post-translational level. The results indicated that late embryogenesis abundant Rab21 was more strongly phosphorylated in the embryos of the sensitive varieties than in the embryos of the tolerant ones. We propose that the differences found in the phosphorylation status of Rab21 are related to stress tolerance.