Genome-wide transcriptome profiling indicates the putative mechanism underlying enhanced grain size in a wheat mutant.

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Grain size is an important trait for crops. The endogenous hormones brassinosteroids (BRs) play key roles in grain size and mass. In this study, we identified an ethyl methylsulfonate (EMS) mutant wheat line, , with increased grain size, 1000-grain weight, and protein content, but decreased starch content, compared with the levels in the wild type (WT). Comparative transcriptomic analysis of and WT at four developmental stages [9, 15, 20, and 25 days post-anthesis (DPA)] revealed a total of 264, 267, 771, and 1038 differentially expressed genes (DEGs) at these stages. Kyoto Encyclopedia of Genes and Genomes (KEGG) database analysis showed that some DEGs from the comparison at 15 DPA were involved in the pathway of "brassinosteroid biosynthesis," and eight genes involved in BR biosynthesis and signal transduction were significantly upregulated in during at least one stage. This indicated that the enhanced BR signaling in might have contributed to its increased grain size via network interactions. The expression of seed storage protein (SSP)-encoding genes in was upregulated, mostly at 15 and 20 DPA, while most of the starch synthetase genes showed lower expression in at all stages, compared with that in WT. The expression patterns of starch synthase genes and seed storage protein-encoding genes paralleled the decreased level of starch and increased storage protein content of , which might be related to the increased seed weight and wrinkled phenotype.

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The online version contains supplementary material available at 10.1007/s13205-020-02579-6.