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Title: Biology in the dry seed: transcriptome changes associated with Arabidopsis seed dormancy and dormancy loss in the GA-insensitive sleepy1 mutant

item NELSON, SVEN - Washington State University
item ARIIZUMI, TOHRU - University Of Tsukuba
item Steber, Camille

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2017
Publication Date: 12/22/2017
Citation: Nelson, S.K., Ariizumi, T., Steber, C.M. 2017. Biology in the dry seed: transcriptome changes associated with Arabidopsis seed dormancy and dormancy loss in the GA-insensitive sleepy1 mutant. Frontiers in Plant Science.

Interpretive Summary: The plant embryo (baby plant) is an a state of suspended animation in a dry seed. The decisions to wake up and germinate is one of the most important decisions in the plant's life. It is essential to species survival and successful agriculture. Dormant seeds cannot germinate at maturity, but acquire the ability to germinate during a period of dry storage called after-ripening. Little is known about how a dry seed can be programmed to wake up at the right time. This study characterized transcript level changes that occur during the unique process of dry after-ripening, and showed that some of these after-ripening regulated genes are biologically important for dormancy loss.

Technical Abstract: Plant embryos can survive years in a desiccated, quiescent state within seeds. In many species, seeds are dormant and unable to germinate at maturity. They acquire the capacity to germinate through a period of dry storage called after-ripening (AR). After-ripening is a biological process that occurs at 5-15% moisture, when most metabolic processes cease. Because the stored transcripts in dry seeds are among the first proteins translated upon imbibition, they may regulate germination potential. To explore the mystery of after-ripening, we examined transcriptome changes associated with increased seed dormancy in the GA-insensitive sly1-2 mutant, and with dormancy loss through after-ripening of dry sly1-2 seeds. Much of the differential transcript accumulation observed was correlated with transcript stability, such that apparently AR-up-regulated transcripts were more stable, and AR-down-regulated transcripts were less stable. This is consistent with the notion that most changes in transcript levels with AR are due to differential mRNA turnover. Translation-associated genes represented 6-12% of AR-up-regulated transcripts in imbibed wild-type seeds. The SLY1 gene was needed both for the down-regulation of this gene family in dry seeds, and for its normal up-regulation with after-ripening in imbibing seeds. The histone deacetylase HDA6/SIL1 (MODIFIERS OF SILENCING1) appeared to be a positive regulator of seed dormancy, since mutations in this AR-down-regulated gene led to decreased seed dormancy. An inhibitor of histone deacetylase partially rescued the seed dormancy of sly1-2. Thus, sly1-2 seed dormancy appears to result in part from altered regulation of protein translation and from altered chromatin structure via histone modification.