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Temperature-sensitive genic male sterile (TGMS) line Beijing Sterility 366 (BS366) has been utilized in hybrid breeding for a long time, but the molecular mechanism underlying male sterility remains unclear. Expression arrays, small RNA, and degradome sequencing were used in this study to explore the potential role of miRNA in the cold-induced male sterility of BS366. Microspore observation showed defective cell plates in dyads and tetrads and shrunken microspores at the vacuolated stage. Differential regulation of Golgi vesicle transport, phragmoplast formation, sporopollenin biosynthesis, pollen exine formation, and lipid metabolism were observed between cold and control conditions. Pollen development was significantly represented in the 352 antagonistic miRNA-target pairs in the integrated analysis of miRNA and mRNA profiles. The specific cleavage of ARF17 and TIR1 by miR160 and miR393 were found in the cold-treated BS366 degradome, respectively. Thus, the cold-mediated miRNAs impaired cell plate formation through repression of Golgi vesicle transport and phragmoplast formation. The repressed expression of ARF17 and TIR1 impaired pollen exine formation. The results of this study will contribute to our understanding of the roles of miRNAs in male sterility in wheat. [ABSTRACT FROM AUTHOR]

Background: Histone methylation usually plays important roles in plant development through post-translational regulation and may provide a new visual field for heterosis. The histone methyltransferase gene family has been identified in various plants, but its members and functions in hybrid wheat related in heterosis is poorly studied. Results: In this study, 175 histone methyltransferase (HMT) genes were identified in wheat, including 152 histone lysine methyltransferase (HKMT) genes and 23 protein arginine methyltransferase (PRMT) genes. Gene structure analysis, physicochemical properties and subcellular localization predictions of the proteins, exhibited the adequate complexity of this gene family. As an allohexaploid species, the number of the genes (seven HKMTs orthologous groups and four PRMTs orthologous groups) in wheat were about three times than those in diploids and showed certain degrees of conservation, while only a small number of subfamilies such as ASH-like and Su-(var) subfamilies have expanded their members. Transcriptome analysis showed that HMT genes were mainly expressed in the reproductive organs. Expression analysis showed that some TaHMT genes with different trends in various hybrid combinations may be regulated by lncRNAs with similar expression trends. Pearson correlation analysis of the expression of TaHMT genes and two yield traits indicated that four DEGs may participate in the yield heterosis of two-line hybrid wheat. ChIP-qPCR results showed that the histone modifications (H3K4me3, H3K36me3 and H3K9ac) enriched in promoter regions of three TaCCA1 genes which are homologous to Arabidopsis heterosis-related CCA1/LHY genes. The higher expression levels of TaCCA1 in F1 than its parents are positive with these histone modifications. These results showed that histone modifications may play important roles in wheat heterosis. Conclusions: Our study identified characteristics of the histone methyltransferase gene family and enhances the understanding of the evolution and function of these members in allohexaploid wheat. The causes of heterosis of two-line hybrid wheat were partially explained from the perspective of histone modifications. [ABSTRACT FROM AUTHOR]

Developing cultivars with improved Pi use efficiency is essential for the sustainability of agriculture as well as the environment. Phosphate starvation response (PHR) regulators have not yet been systematically studied in wheat. This study provides the detailed characteristics of PHRs in hexaploid wheat as well as other major gramineous plants at the genome-wide level. The identified PHR proteins were divided into six subfamilies through phylogeny analysis, and a total of 63 paralogous TaPHR pairs were designated as arising from duplication events, with strong purifying selection. The promoters of TaPHRs were identified as stations for many transcription factors. Protein–protein interaction network and gene ontology enrichment analysis indicated a core biological process of cellular response to phosphate starvation. The three-dimensional structures of core PHR proteins showed a high phylogenetic relationship, but amino acid deletions in core protein domains may cause functional differentiation between rice and wheat. TaPHR3 could interact with TaSPX1 and TaSPX5 proteins, which is regarded as a novel interaction mode. Under different Pi gradient treatments, TaPHR s showed low inducible expression patterns among all subfamilies. Our study is the first to comprehensively clarify the basic properties of TaPHR proteins and might accumulate basic data for improving grain yield and environmental homeostasis. [ABSTRACT FROM AUTHOR]

Abstract: MicroRNAs (miRNAs) represent a class of endogenous regulator for post-transcriptionally modulating gene expression. Elucidating complete miRNA repertoires for individual species is a long-desired goal in miRNA research. So far only 42 have been annotated for common wheat (Triticum aestivum) due to its large genome. Here, we employed miRDeep-P, a program developed previously for retrieving miRNAs from deep sequencing data in plants, to parse 14 sequenced small RNA libraries of wheat using expression sequence tags (ESTs) as the reference in lieu of a complete genome sequence. This effort identified 145 miRNAs along with the corresponding stem-looped precursors with many differentially expressed in development and associated with powdery mildew infection. Examination of the phylogenetic distribution of these miRNAs and their target genes revealed that many are conserved in monocots. The set of miRNAs identified in this study is thus useful to further miRNA research in wheat and other important cereal crop species. [Copyright &y& Elsevier]

• The wheat CHS family members were identified. • Several TaCHSs showed anther-specific expression patterns. • TaCHSs co-expressed with potential anther sporopollenin biosynthetic genes. • TaLAP5 (TaCHS3 , TaCHS10) and TaLAP6 (TaCHS64, TaCHS67) may be involved in the cold-induced male sterility in BS366. Chalcone synthase (CHS), also known as the plants-specific type III polyketide synthases (PKSs), catalyzes the first key step in the biosynthesis of plant flavonoids. Flavonoids are one of the most important secondary metabolites which participate in flower pigmentation and pollen fertility. Recent reports have demonstrated the role of the CHS family in plant pollen exine formation. This study focused on the potential roles of CHS in the pollen exine formation of wheat. In the present study, a genome-wide investigation of the CHS family was carried out, and 87 CHS genes were identified in wheat. TaCHS3 , TaCHS10 , and TaCHS13 are wheat orthologs of Arabidopsis LESS ADHESIVE POLLEN (LAP5); TaCHS58 , TaCHS64 , and TaCHS67 are wheat orthologs of AtLAP6. TaCHS3 , TaCHS10 , and TaCHS67 showed anther-specific patterns. The expression of TaCHS3 , TaCHS10, and TaCHS67 was positively co-expressed with sporopollenin biosynthetic genes, including TaCYP703A2 , TaCYP704B1 , TaDRL1 , TaTKPR2 , and TaMS2. Coincidently, the expression of TaCHS3 , TaCHS10, and TaCHS67 , together with those sporopollenin biosynthetic genes, were repressed at the tetrads and uninucleate stages in the temperature-sensitive genic male-sterile (TGMS) line BS366 under sterile conditions. Wheat anther-specific CHS genes might participate in the exine formation of BS366 through co-expressing with sporopollenin biosynthetic genes, which will undoubtedly provide knowledge of the roles of CHS in wheat pollen development. [ABSTRACT FROM AUTHOR]

The 12-oxo-phytodienoic acid reductases (OPRs) are involved in the various processes of growth and development in plants, and classified into the OPRⅠ and OPRⅡ subgroups. In higher plants, only OPRⅡ subgroup genes take part in the biosynthesis of endogenous jasmonic acid. In this study, we isolated a novel OPRⅡ subgroup gene named TaOPR2 (GeneBank accession: KM216389) from the thermo-sensitive genic male sterile (TGMS) wheat cultivar BS366. TaOPR2 was predicted to encode a protein with 390 amino acids. The encoded protein contained the typical oxidored_FMN domain, the C-terminus peroxisomal-targeting signal peptide, and conserved FMN-binding sites. TaOPR2 was mapped to wheat chromosome 7B and located on peroxisome. Protein evolution analysis revealed that TaOPR2 belongs to the OPRⅡ subgroup and shares a high degree of identity with other higher plant OPR proteins. The quantitative real-time PCR results indicated that the expression of TaOPR2 is inhibited by abscisic acid (ABA), salicylic acid (SA), gibberellic acid (GA 3 ), low temperatures and high salinity. In contrast, the expression of TaOPR2 can be induced by wounding, drought and methyl jasmonate (MeJA). Furthermore, the transcription level of TaOPR2 increased after infection with Puccinia striiformis f. sp . tritici and Puccinia recondite f. sp . tritici . TaOPR2 has NADPH-dependent oxidoreductase activity. In addition, the constitutive expression of TaOPR2 can rescue the male sterility phenotype of Arabidopsis mutant opr3 . These results suggest that TaOPR2 is involved in the biosynthesis of jasmonic acid (JA) in wheat. [ABSTRACT FROM AUTHOR]