Pre-harvest sprouting (PHS), the germination of grain before harvest, is a serious problem resulting in wheat yield and quality losses.Here, we mapped the PHS resistance gene PHS-3D from synthetic hexaploid wheat to a 2.4 Mb presence-absence variation (PAV) region and found that its resistance effect was attributed to the pleiotropic Myb10-D by integrated omics and functional analyses.Three haplotypes were detected in this PAV region among 262 worldwide wheat lines and 16 Aegilops tauschii, and the germination percentages of wheat lines containing Myb10-D was approximately 40% lower than that of the other lines. Transcriptome and metabolome profiling indicated that Myb10-D affected the transcription of genes in both the flavonoid and abscisic acid (ABA) biosynthesis pathways, which resulted in increases in flavonoids and ABA in transgenic wheat lines. Myb10-D activates 9-cis-epoxycarotenoid dioxygenase (NCED) by biding the secondary wall MYB-responsive element (SMRE) to promote ABA biosynthesis in early wheat seed development stages.We revealed that the newly discovered function of Myb10-D confers PHS resistance by enhancing ABA biosynthesis to delay germination in wheat. The PAV harboring Myb10-D associated with grain color and PHS will be useful for understanding and selecting white grained PHS resistant wheat cultivars.
BackgroundBasic helix-loop-helix (bHLH) transcription factors (TFs), which are widely distributed in eukaryotic organisms, play crucial roles in plant development. However, no comprehensive analysis of the bHLH family in wheat (Triticum aestivum L.) has been undertaken previously.ResultsIn this study, 225 bHLH TFs predicted from wheat using genomic and RNA sequencing data were subjected to identification, classification, phylogenetic reconstruction, conserved motif characterization, chromosomal distribution determination and expression pattern analysis. One basic region, two helix regions and one loop region were found to be conserved in wheat bHLH TFs. The bHLH proteins could be separated into four categories based on sequences in their basic regions. Neighbor-joining-based phylogenetic analysis of conserved bHLH domains from wheat, Arabidopsis and rice identified 26 subfamilies of bHLH TFs, of which 23 were found in wheat. A total of 82 wheat bHLH genes had orthologs in Arabidopsis (27 TFs), rice (28 TFs) and both of them (27 TFs). Seven tissue-specific bHLH TF clusters were identified according to their expression patterns in endosperm, aleurone, seedlings, heading-stage spikes, flag leaves, shoots and roots. Expression levels of six endosperm-specifically expressed TFs measured by qPCR and RNA-seq showed a good correlation.ConclusionThe 225 bHLH transcription factors identified from wheat could be classed into 23 subfamilies, and those members from the same subfamily with similar sequence motifs generally have similar expression patterns.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-017-1038-y) contains supplementary material, which is available to authorized users.
Aureochaeglobosins A-C (1-3), three novel [4 + 2] cycloaddition heterodimers of chaetoglobosin and aureonitol derivatives, were obtained from the culture of endophytic fungus Chaetomium globosum, representing the first adduct examples of chaetoglobosins. Their structures were elucidated by extensive spectroscopic analyses, single-crystal X-ray diffraction, and a modified Mosher's method. Compounds 2 and 3 showed significant cytotoxicities against human MDA-MB-231 cancer cells with IC values of 7.6 and 10.8 μM, respectively.
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