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bioRxiv · 10.1101/846782

Transcriptomic analysis of developing seeds in a wheat mutant RSD32 with reduced seed dormancy

Rikiishi, K.·Sugimoto, M.·Maekawa, M.
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Abstract

Seed dormancy, a major factor regulating pre-harvest sprouting, can severely hinder wheat cultivation. Abscisic acid biosynthesis and sensitivity play important roles in the regulation of seed dormancy. Reduced Seed Dormancy 32 (RSD32), a wheat mutant with reduced seed dormancy, is derived from the pre-harvest sprouting tolerant cultivar, Norin61. RSD32 is regulated by a single recessive gene and mutant phenotype expressed in a seed-specific manner. Results of this study show that Norin61 has a low germination index (GI) of whole seeds at 50 days after pollination (DAP) and earlier developmental stages. In RSD32, higher GI of whole seeds was found on DAP40. Dormancy was released by DAP50. Gene expressions in embryos of Norin61 and RSD32 were compared using RNA-seq analysis at the different developmental stages of DAP20, DAP30, and DAP40. Numbers of up-regulated gene in RSD32 are similar in all developmental stages. However, down-regulated genes in RSD32 are more numerous on DAP20 and DAP30 than on DAP40. Homologous genes related to circadian clock regulation and Ca2+ signaling pathway, which have fundamental functions for plant growth and development, are involved in down-regulated genes in RSD32 on DAP20. For central components affecting the circadian clock, genes homologous to CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), which act as morning expressed genes, are expressed at lower levels in RSD32. However, higher expressions of TIMING OF CAB EXPRESSION 1 (TOC1) and PHYTOCLOCK 1 homologues, acting as evening expressed genes, are observed in RSD32. Homologues of Ca2+ signaling pathway related genes are found to be specifically expressed on DAP20 in Norin61. Lower expression is shown in RSD32. These results suggest that RSD32 mutation expresses on DAP20 and earlier seed developmental stages and suggest that circadian clock regulation and Ca2+ signaling pathway are involved in regulating wheat seed dormancy.

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Rikiishi, K., Sugimoto, M., Maekawa, M.. 2019-11-18. Transcriptomic analysis of developing seeds in a wheat mutant RSD32 with reduced seed dormancy. https://doi.org/10.1101/846782

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