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Sucrose non-fermenting 1-related protein kinase 2 (SnRK2) is a plant-specific serine/threonine kinase involved in response to adverse environmental stimuli. Previous studies showed that TaSnRK2.4 was involved in response to abiotic stresses and conferred enhanced tolerance to multiple stresses in Arabidopsis. Further experiments were performed to decipher the underlying mechanisms and discover new functions. The genomic sequences of TaSnRK2.4s locating on chromosome 3A, 3B and 3D were obtained. Sequencing identified one and 13 variations of TaSnRK2.4–3A and TaSnRK2.4-3B, respectively, but no variation was detected in TaSnRK2.4-3D. The markers 2.4AM1, 2.4BM1 and 2.4BM2 were developed based on three variations. Association analysis showed that both TaSnRK2.4-3A and TaSnRK2.4-3B were significantly associated with thousand-kernel weight (TKW), and that SNP3A-T and SNP3B-C were favorable alleles for higher TKW. Yeast two-hybrid and split luciferase assays showed that TaSnRK2.4 physically interacted with abiotic stress responsive protein TaLTP3, suggesting that TaSnRK2.4 enhanced abiotic stress tolerance by activating TaLTP3. Our studies suggested that TaSnRK2.4 have potential in improving TKW and response to abiotic stress.

Nitrate transporters (NRTs) are regulators of nitrate assimilation and transport. The genome sequences of TaNRT2L12-A, -B and -D were cloned from wheat (Triticum aestivum L.), and polymorphisms were analyzed by sequencing. TaNRT2L12-D in a germplasm population was highly conserved. However, 38 single nucleotide polymorphisms (SNPs) in TaNRT2L12-A coding region and 11 SNPs in TaNRT2L12-B coding region were detected. Two derived cleaved amplified polymorphic sequences (dCAPS) markers A-CSNP1 and A-CSNP2 were developed for TaNRT2L12-A based on SNP-351 and SNP-729, and three haplotypes were identified in the germplasm population. B-CSNP1 and B-CSNP2 were developed for TaNRT2L12-B based on SNP-237 and SNP-1227, and three haplotypes were detected in the germplasm population. Association analyses between the markers and agronomic traits in 30 environments and phenotypic comparisons revealed that A-CSNP2-A is a superior allele of shorter plant height (PH), length of penultimate internode (LPI) and peduncle length (PL), B-CSNP2-G is a superior allele of higher grain number per spike (GNS). Hap-6B-1 containing both superior alleles B-CSNP1-C and B-CSNP2-A is a superior haplotype of 1 000-grain weight (TGW). Expression analysis showed that TaNRT2L12-B is mainly expressed in the root base and regulated by nitrate. Therefore, TaNRT2L12 may be involved in nitrate transport and signaling to regulate TGW in wheat. The superior alleles and dCAPS markers of TaNRT2L12-A/B are beneficial to genetic improvement and germplasm enhancement with molecular markers-assisted selection.

The stress-associated protein (SAP) multigene family is conserved in both animals and plants. Its function in some animals and plants are known, but it is yet to be deciphered in wheat (Triticum aestivum L.). We identified the wheat gene TaSAP17-D, a member of the SAP gene family with an AN1/AN1 conserved domain. Subcellular localization indicated that TaSAP17-D localized to the nucleus, cytoplasm, and cell membrane. Expression pattern analyses revealed that TaSAP17-D was highly expressed in seedlings and was involved in NaCl response, polyethylene glycol (PEG), cold, and exogenous abscisic acid (ABA). Constitutive expression of TaSAP17-D in transgenic Arabidopsis resulted in enhanced tolerance to salt stress, confirmed by improved multiple physiological indices and significantly upregulated marker genes related to salt stress response. Our results suggest that TaSAP17-D is a candidate gene that can be used to protect crop plants from salt stress.

Fructans are major nonstructural carbohydrates in wheat (Triticum aestivum L.). Fructan 1-fructosyltransferase (1-FFT) is the key enzyme in fructan biosynthesis. In the present study, 96 sequence variants were detected in the 1-FFT-A1 gene among 26 wheat accessions including UR208, and 15 of them result in amino acid substitutions, forming four haplotypes. Two markers M39 and M2164 were developed based on the InDel21-39 and SNP-2164 polymorphisms to distinguish the three haplotypes in the 1-FFT-A1. 1-FFT-A1 was located on chromosome 4A using marker M2164 and was flanked by markers Xcwm27 and 6-SFT-A1. By association analysis using a natural wheat population consisted of 154 accessions, the results showed that the two markers were significantly associated with water-soluble carbohydrate (WSC) content in the lower internode stem and total stem at the early and middle grain filling stages, 1000-grain weight (TGW) at different grain filling stages and peduncle length (PLE). Comparison of the effects of three haplotypes on agronomic traits indicated that TGW, PLE and total number of spikelets per spike (TNSS) were significantly influenced by haplotypes. HapIII showed a significant positive effect on TGW, PLE and TNSS.

AREB (ABA response element binding) proteins in plants play direct regulatory roles in response to multiple stresses, but their functions in wheat (Triticum aestivum L.) are not clear. In the present study, TaAREB3, a new member of the AREB transcription factor family, was isolated from wheat. Sequence analysis showed that the TaAREB3 protein is composed of three parts, a conserved N-terminal, a variable M region, and a conserved C-terminal with a bZIP domain. It belongs to the group A subfamily of bZIP transcription factors. TaAREB3 was constitutively expressed in stems, leaves, florets, anthers, pistils, seeds, and most highly, in roots. TaAREB3 gene expression was induced with abscisic acid (ABA) and low temperature stress, and its protein was localized in the nucleus when transiently expressed in tobacco epidermal cells and stably expressed in transgenic Arabidopsis. TaAREB3 protein has transcriptional activation activity, and can bind to the ABRE cis-element in vitro. Overexpression of TaAREB3 in Arabidopsis not only enhanced ABA sensitivity, but also strengthened drought and freezing tolerances. TaAREB3 also activated RD29A, RD29B, COR15A, and COR47 by binding to their promoter regions in transgenic Arabidopsis. These results demonstrated that TaAREB3 plays an important role in drought and freezing tolerances in Arabidopsis.

Stress-associated protein (SAP) has functions in maintaining plant cell elongation, embryo development and response to abiotic stresses. TaSAP1-A1 , one of the Triticum aestivum SAP1 ( TaSAP1 ) members located on wheat chromosome 7A was isolated for polymorphism analysis. Hap III of TaSAP1-A1 was found significantly associated with thousand-grain weight (TGW) in multiple environments. In this study, Hap III also made a positive contribution to TGW in Population 2. The distribution of TaSAP1-A1 Hap III was tracked among varieties released in different years and geographical environments of China. The frequency of Hap III showed an increasing trend during the breeding process in two different populations. The Hap III was gradually selected and applied from 6.36% in landraces to 13.50% in modern varieties. These results exhibited that TaSAP1-A1 Hap III was positively selected during wheat breeding, which is beneficial for grain-yield improvement. The preferred Hap III was initially selected and applied in the higher latitude areas of China in accord with the long day season and longer grain filling stage in these areas. Moreover, the frequency of Hap III in recent modern varieties was still quite low (19.29–26.67%). It indicated a high application potential of TaSAP1-A1 Hap III for improving grain yield in wheat breeding.

Wheat is an important source of essential minerals for human body. Breeding wheat with high grain mineral concentration thus benefits human health. The objective of present study was to identify quantitative trait loci (QTLs) controlling grain mineral concentration and to evaluate the relation between nitrogen (N) and other essential minerals in winter wheat. Wheat grains were harvested from field experiment which conducted in China and analyzed for this purpose. Forty-three QTLs controlling grain mineral concentration and nitrogen-related traits were detected by using a double haploid (DH) population derived from winter wheat varieties Hanxuan 10 and Lumai 14. Chromosomes 4D and 5A might be very important in controlling mineral status in wheat grains. Significant positive correlations were found between grain nitrogen concentration (GNC) and nutrients Fe, Mn, Cu, Mg concentrations (FeGC, MnGC, CuGC, MgGC). Flag leaf N concentration at anthesis (FLNC) significantly and positively correlated with GNC, FeGC, MnGC, and CuGC. The study extended our knowledge on minerals in wheat grains and suggested which interactions between minerals should be considered in future breeding program.

Drought as a major abiotic stress often occurs from stem elongation to the grain filling stage of wheat in northern China. Plant height (PH) is a suitable trait to model the dissection of drought tolerance. The purposes of the present study were to validate molecular markers for PH developmental behavior and identify elite alleles of molecular markers. After the phenotyping of 154 accessions for PH dynamic development under well-watered (WW) and drought stressed (DS) conditions, and the genotyping of 60 SSR markers from six candidate chromosome regions related to PH found in our previous linkage mapping studies, both parameters PH and drought tolerance coefficient (DTC) calculated by the conditional analysis were used for association mapping. A total of 46 significant association signals (P

Plant cysteine protease (CP) genes are induced by abiotic stresses such as drought, yet their functions remain largely unknown. We isolated the full-length cDNA encoding a Triticum aestivum CP gene, designated TaCP, from wheat by the rapid amplification of cDNA ends (RACE) method. Sequence analysis revealed that TaCP contains an open reading frame encoding a protein of 362 amino acids, which is 96% identical to barley cysteine protease HvSF42. The TaCP transcript level in wheat seedlings was upregulated during polyethylene glycol (PEG) stress, with a peak appearing around 12 h after treatment. TaCP expression level increased rapidly with NaCl treatment at 48 h. TaCP responded strongly to low temperature (4 degree C) treatment from 1 h post-treatment and reached a peak of about 40-fold at 72 h. However, it showed only a very slight response to abscisic acid (ABA). More than one copy of TaCP was present in each of the three genomes of hexaploid wheat and its diploid donors. TaCP fused with green fluorescent protein (GFP) was located in the plasma membrane of onion epidermis cells. Transgenic Arabidopsis plants overexpressing TaCP showed stronger drought tolerance and higher CP activity under water-stressed conditions than wild-type Arabidopsis plants. The results suggest that TaCP plays a role in tolerance to water deficit.

Plant height (PH) reduction has obviously contributed to lodging resistance and yield increase of wheat (Triticum aestivum L.) in the last decades. The objectives of this study were to understand the diversity status of wheat cultivars in northern China and to identify simple sequence repeat (SSR) markers associated with PH. Using 117 SSR markers evenly distributed on wheat chromosomes, a total of 1484 alleles were detected in 136 winter wheat cultivars that were historically planted in northern China. The average allele number per locus ranged from 2 to 42 with an average of 12.6. The polymorphism information content (PIC) values ranged from 0.016 to 0.941 with an average of 0.640. Based on the cluster tree, the cultivars developed by the same breeders or kin cultivars were gathered in the same subgroup. Some cultivars with similar ecotypes or developed contemporaneously also fell into the same subgroup. Nineteen SSRs each were significantly associated with PH under drought and well-watered conditions, respectively (P

Drought is one of the most adverse environmental factors that impact on plant growth and reduce crop yields. To decipher the molecular mechanism of drought tolerance, we constructed a cDNA library using suppression subtractive hybridization (SSH) and dissected the gene expression profiles in seedling and jointing wheat plants after stress with PEG-6000. A total of 2 046 ESTs from the jointing stage library (J-Lib) were allocated to 961 contigs. Among the ESTs, 265 uni-genes in 12 categories were identified on the basis of sequence similarities and functional classifications. Most were known to be involved in protection, directly or indirectly, against water stress. To determine differences in gene expression profiles for water stress responses at the jointing and seedling stages, data from the J-Lib were compared with those from a 2-leaf seedling library (S-Lib) constructed by the same method. Significant differences were observed between the two libraries for function-known genes; signal transduction genes were far more active at jointing than at the seedling stage.

Delta(1)-pyrroline-5-carboxylate synthetase (P5CS) is the rate-limiting enzyme involved in the biosynthesis of proline in plants. By the 3' rapid amplification of cDNA ends (3'-RACE) approach, a 2,246-bp cDNA sequence was obtained from common bean (Phaseolus vulgaris L.), denominated PvP5CS2 differing from another P5CS gene that we cloned previously from common bean (PvP5CS). The predicted amino acid sequence of PvP5CS2 has an overall 93.2% identity GmP5CS (Glycine max L. P5CS). However, PvP5CS2 shows only 83.7% identity in amino acid sequence to PvP5CS, suggesting PvP5CS2 represents a homolog of the soybean P5CS gene. Abundant indel (insertion and deletion events) and SNP (single nucleotide polymorphisms) were found in the cloned PvP5CS2 genome sequence when comparing 24 cultivated and 3 wild common bean accessions and these in turn reflected aspects of common bean evolution. Sequence alignment showed that genotypes from the same gene pool had similar nucleotide variation, while genotypes from different gene pools had distinctly different nucleotide variation for PvP5CS2. Furthermore, diversity along the gene sequence was not evenly distributed, being low in the glutamic-g-semialdehyde dehydrogenase catalyzing region, moderate in the Glu-5-kinase catalyzing region and high in the intervening region. Neutrality tests showed that PvP5CS2 was a conserved gene undergoing negative selection. A new marker (Pv97) was developed for genetic mapping of PvP5CS2 based on an indel between DOR364 and G19833 sequences and the gene was located between markers Bng126 and BMd045 on chromosome b01. The relationship of PvP5CS2 and a previously cloned pyrroline-5-carboxylate synthetase gene as well as the implications of this work on selecting for drought tolerance in common bean are discussed.

A full-length cDNA denominated PvP5CS for Delta(1)-pyrroline-5-carboxylate synthetase (P5CS), an enzyme involved in the biosynthesis of proline, was cloned from common bean using a candidate gene approach. PvP5CS contains an open reading frame encoding a 716 amino acid polypeptide. Sequence analysis showed that PvP5CS shares 95.1% homology in nucleotide sequence and 93.2% identity in amino acid sequence with the mothbean (Vigna aconitifolia) P5CS. The expression patterns of PvP5CS in common bean treated with drought, cold (4 degrees C), and salt (200 mM NaCl) stresses were examined using real-time quantitative PCR. These abiotic stresses caused significant up-regulation of the expression of PvP5CS in leaves. The PvP5CS mRNA transcript increased to 2.5 times the control level after 4d drought stress. A rapid up-regulation of PvP5CS, to about 16.3 times the control at 2h post-treatment was observed under salt stress. A significant increase in PvP5CS expression (11.7-fold) was detected after 2h of cold stress. The peaks of proline accumulation appeared at 8d for drought, 24h for cold and 9h for salt stress, somewhat later than the peaks of PvP5CS expression. These results suggest that PvP5CS was a stress-inducible gene regulating the accumulation of proline in plants subjected to stress. Finally, subcellular localization assays showed that the PvP5CS protein was present in the nucleus and at the plasmalemma.

Zinc (Zn) is an essential micronutrient for human beings. However, Zn malnutrition has become a major problem throughout the world. Wheat is the most important food crop in the world, therefore, developing Zn-enriched wheat varieties provides an effective approach to reduce Zn malnutrition in human beings. The aim of this study was to understand the genetic control of grain Zn density in wheat and hence, to provide genetic basis for breeding wheat with high grain Zn density using molecular approach. A doubled haploid (DH) popu- lation developed from a cross between winter wheat varieties Hanxuan10 and Lumai 14 was used to identify quantitative trait loci (QTLs) for Zn concen- tration and content in wheat grains. In addition, phosphorus (P) concentration and content in wheat grain were also investigated to examine possible interactions between these two nutrients. The wheat grains used in this study were harvested from the plants grown under normal condition in a field trial. We found the grain Zn concentrations of the DH population varied from 25.9 to 50.5 mg/kg and the Zn content varied from 0.90 to 2.21 μg/seed. The grain P concentrations of the DH population varied from 0.258 to 0.429 mg/kg, and the P contents varied from 0.083 to 0.186 mg/seed. A significant positive correlation was observed between Zn and P density in this experiment. The results showed that both grain Zn and P densities were controlled by polygenes. Four and seven QTLs for Zn concentration and Zn content were detected, respectively. All the four QTLs for Zn concentration co-located with the QTLs for Zn content, suggesting a possibility to improve both grain Zn concentration and content simultaneously. Four and six QTLs for P concentration and P content were detected, respectively. The two QTLs for grain Zn concentration on chromosomes 4A and 4D co- located with the QTLs for P concentration. The four QTLs for grain Zn content on chromosome 2D, 3A and 4A co-located with the QTLs for P contents, reflecting the positive correlations between the grain Zn and P density, and providing possibility of improving grain micro- and macronutrient density simultaneously in wheat. In order to improve human health, the effect of P-Zn relation in grain on the Zn bioavailability should also be considered in the future

Parameters of chlorophyll fluorescence kinetics (PCFKs) under drought stress condition are generally used to characterize instincts for dehydration tolerance in wheat (Triticum aestivum L.). Therefore, it is important to map quantitative trait loci (QTLs) for PCFKs in wheat genetic improvement for drought tolerance. A doubled haploid (DH) population with 150 lines, derived from a cross between two common wheat varieties, Hanxuan 10 and Lumai 14, was used to analyze the correlation between PCFKs and chlorophyll content (ChlC) and to map QTLs at the grain-filling stage under conditions of both rainfed (drought stress, DS) and well-watered (WW), respectively. QTLs for these traits were detected by QTLMapper version 1.0 based on the composite interval mapping method of the mixed-linear model. The results showed a very significant positive correlation between Fv, Fm, Fv/Fm and Fv/Fo. The correlation coefficients were generally higher under WW than under DS. Also, there was a significant or a highly significant positive correlation between Fv, Fm, Fv/Fm, Fv/Fo and ChlC. The correlation coefficients were higher in the DS group than the WW group. A total of 14 additive QTLs (nine QTLs detected under DS and five QTLs under WW) and 25 pairs of epistatic QTLs (15 pairs detected under DS and 10 pairs under WW) for PCFKs were mapped on chromosomes 6A, 7A, 1B, 3B, 4D and 7D. The contributions of additive QTLs for PCFKs to phenotype variation were from 8.40% to 72.72%. Four additive QTLs (two QTLs detected under DS and WW apiece) controlling ChlC were mapped on chromosomes 1A, 5A and 7A. The contributions of these QTLs for ChlC to phenotype variation were from 7.27% to 11.68%. Several QTL clusters were detected on chromosomes 1B, 7A and 7D, but no shared chromosomal regions for them were identified under different water regimes, indicating that these QTLs performed different expression patterns under rainfed and well-watered conditions. (Handling editor: Yong-Biao Xue)

1The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, People’s Republic of China 2College of Tobacco Science, Henan Agricultural University, Zhengzhou 450002, People’s Republic of China 3Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, People’s Republic of China

Taking the DH population of wheat cultivar Hanxuan10/Lumai14 as test object, and by the methods of correlation analysis and path analysis, this paper studied the relationships of the flag leaf stomatal density (SD), stomatal length and width (SL and SW), stomatal conductance (g(s)), photosynthetic rate (P(n)), and transpiration rate (T(r)) on the 10th and 20th day after anthesis with the yield and the index of drought-resistance under the conditions of drought stress and normal irrigation. Under the two conditions, most of the test leaf traits on the 10th day after anthesis had less correlation with the yield and the index of drought-resistance, whereas the leaf traits on the 20th day after anthesis had significant positive correlations with thousand kernel weight but less correlation with grain number per ear, grain yield per plant, and index of drought-resistance. Path analysis showed that g(s), P(n), and T(r) were the main factors affecting the grain yield per plant (YPP) and the index of drought resistance (IDR), and the effects were stronger both in direct and in indirect ways. The direct and indirect effects of SD, SL, and SW on the YPP and IDR were lesser. Under both drought stress and normal irrigation, and on the 10th and 20th day after anthesis, there were significant correlations between SD and SL, and between SL and SW, g(s), P(n), and Tr, but the correlations of SD and SL with g(s), P(n), and T(r) changed with water condition or growth stage. Therefore, it would be not always a good means to select the leaf stomatal density and size as the targets for breeding to improve the leaf stomatal conductance, photosynthetic rate, and transpiration rate, and further, to promote the yield.

Taking one hundred and fifty doubled haploid (DH) lines of winter wheat cultivars Hanxuan 10 x Lumai 14 as well as their parents as test materials, the genetic bases of top three leaves length, breadth, and angle at mid-filling stage, and their correlations with yield traits were studied under two water regimes rainfed (drought stress, DS) and well-irrigation (WI) in 2005-2007. Under DS, the leaf length and width of DH lines and their parents were significantly lower than those under WI, whereas the leaf angle had a miscellaneous variation. Under the two water regimes, all the test traits of DH lines had a transgressive segregation, with the variation coefficients ranged from 5.1% to 45.9%. The heritability and gene numbers for the given traits showed great differences. Under WI and DS, the heritability of flag leaf angle (FLA) was the highest (91% and 97%, respectively), and that of the third leaf angle (TLA) was the lowest (23% and 31%, respectively). However, the gene number for FLA (4 and 2 under WI and DS, respectively) was the least, and that of TLA (21 and 25, respectively) in 2007 was the most. Interactive effects were observed among the genes controlling FLA, second leaf angle (SLA), and TLA under WI and DS, and controlling third leaf length (TLL) under WI. The grain number per spike and the grain weight per spike were positively correlated with the length and width of top three leaves, and the thousand-grain weight and the yield per plant were significantly correlated with TLL, FLA, and SLA, but all correlation coefficients were smaller (0.481). It was suggested that the selection of top three leaves length and width should be carried out in the early generations of breeding procedure, while that of leaf angles should be carried out in advanced generations. An appropriate soil moisture regime retained in the critical growth period of the leaves would promote their growth and contribute to the grain yield.

Calreticulin (CRT) is a key Ca2+-binding protein mainly resident in the endoplasmic reticulum (ER), which is highly conserved and extensively expressed in all eukaryotic organisms investigated. The protein plays important roles in a variety of cellular processes including Ca2+ signaling and protein folding. Although calreticulin has been well characterized in mammalian systems, increased investigations have demonstrated that plant CRTs have a number of specific properties different from their animal counterparts. Recent developments on plant CRTs have highlighted the significance of CRTs in plants growth and development as well as biotic and abiotic stress responses. There are at least two distinct groups of calreticulin isoforms in higher plants. Glycosylation of CRT was uniquely observed in plants. In this article, we will describe our current understanding of plant calreticulin gene family, protein structure, cellular localization, and diverse functions in plants. We also discuss the prospects of using this information for genetic improvements of crop plants.

Calreticulin (CRT) is a highly conserved and ubiquitously expressed Ca(2+)-binding protein in multicellular eukaryotes. CRT plays a crucial role in many cellular processes including Ca(2+) storage and release, protein synthesis, and molecular chaperone activity. To elucidate the function of CRTs in plant responses against drought, a main abiotic stress limiting cereal crop production worldwide, a full-length cDNA encoding calreticulin protein namely TaCRT was isolated from wheat (Triticum aestivum L.). The deduced amino acid sequence of TaCRT shares high homology with other plant CRTs. Phylogenetic analysis indicates that TaCRT cDNA clone encodes a wheat CRT3 isoform. Southern analysis suggests that the wheat genome contains three copies of TaCRT. Subcellular locations of TaCRT were the cytoplasm and nucleus, evidenced by transient expression of GFP fused with TaCRT in onion epidermal cells. Enhanced accumulation of TaCRT transcript was observed in wheat seedlings in response to PEG-induced drought stress. To investigate further whether TaCRT is involved in the drought-stress response, transgenic plants were constructed. Compared to the wild-type and GFP-expressing plants, TaCRT-overexpressing tobacco (Nicotiana benthamiana) plants grew better and exhibited less wilt under the drought stress. Moreover, TaCRT-overexpressing plants exhibited enhanced drought resistance to water deficit, as shown by their capacity to maintain higher WUE (water use efficiency), WRA (water retention ability), RWC (relative water content), and lower MDR (membrane damaging ratio) (P < or = 0.01) under water-stress conditions. In conclusion, a cDNA clone encoding wheat CRT was successfully isolated and the results suggest that TaCRT is involved in the plant response to drought stress, indicating a potential in the transgenic improvements of plant water-stress.

Genetic analyses of nine traits associated with stem water-soluble carbohydrate (SWSC) accumulation and remobilization at grain-filling period under drought stress (DS) and well-watered (WW) conditions were undertaken using doubled haploid lines (DHLs) derived from two Chinese common wheat cultivars. Some significantly and very significantly positive correlation was observed among nine traits associated with SWSC. Higher phenotypic values for most traits were detected under DS. Broad sense heritabilities (\documentclass[10pt]{article} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{pmc} \pagestyle{empty} \oddsidemargin -1.0in \begin{document} \begin{equation*}h_{{\mathrm{B}}}^{2}\end{equation*}\end{document}) of the traits showed wide fluctuations between two water treatments. A total of 48 additive and 62 pairs of epistatic QTL for nine traits were identified as distributing on all 21 chromosomes. A majority of QTL involved significant additive and epistatic effects with interactions of QTL and environments (QEIs). Two additive and two pairs of epistatic loci involved only QEIs without corresponding significant additive or epistatic effects. The contributions of the additive QEIs were two- to fourfolds higher than those of their corresponding additive QTL. Most of the additive QEIs for traits associated with SWSC interacted with DS. In addition, some QTL for the grain-filling efficiencies and thousand-grain weight were colocated in the same or adjacent chromosome intervals with QTL for accumulation and remobilization efficiency of SWSC before 14 days after flowering.

†Background and Aims Multiple copies of genes encoding the catalytic subunit (c) of protein phosphatase 2A (PP2A) are commonly found in plants. For some of these genes, expression is up-regulated under water stress. The aim of this study was to investigate expression and characterization of TaPP2Ac-1 from Triticum aestivum, and to evaluate the effects of TaPP2Ac-1 on Nicotiana benthamiana in response to water stress. †Methods TaPP2Ac-1 cDNA was isolated from wheat by in silico identification and RT-PCR amplification. Transcript levels of TaPP2Ac-1 were examined in wheat responding to water deficit. Copy numbers of TaPP2Ac-1 in wheat genomes and subcellular localization in onion epidermal cells were studied. Enzyme properties of the recombinant TaPP2Ac-1 protein were determined. In addition, studies were carried out in tobacco plants with pCAPE2-TaPP2Ac-1 under water-deficit conditions. †Key Results TaPP2Ac-1 cDNA was cloned from wheat. Transcript levels of TaPP2Ac-1 in wheat seedlings were up-regulated under drought condition. One copy for this TaPP2Ac-1 was present in each of the three wheat genomes. TaPP2Ac-1 fused with GFP was located in the nucleus and cytoplasm of onion epidermis cells. The recombinant TaPP2Ac-1 gene was over-expressed in Escherichia coli and encoded a functional serine/threonine phosphatase. Transgenic tobacco plants over-expressing TaPP2Ac-1 exhibited stronger drought tolerance than nontransgenic tobacco plants. †Conclusions Tobacco plants with pCAPE2-TaPP2Ac-1 appeared to be resistant to water deficit, as shown by their higher capacity to maintain leaf relative water content, leaf cell-membrane stability index, water-retention ability and water use efficiency under water stress. The results suggest that the physiological role of TaPP2Ac-1 is related to drought stress response, possibly through its involvement in drought-responding signal transduction pathways.

The use of full-length cDNA libraries is an effective tool to obtain complete gene information in a high-efficiency, high-throughput manner, especially in organisms with huge genomes that are not amenable to whole genome sequencing. In this review, we outlined several methods of full-length cDNA library construction and compared their advantages and disadvantages based on their respective principles. Drawing on our own experience, we described the Cap-trapper method in detail, with an emphasis on its application in wheat full-length cDNA library construction as well as the determination of the ratio of full-length cDNA in a library.