Preliminary Analysis Of The Mechanism Of Histone Deacetylase Inhibitors In Regulating Sugar Beet Vernalization

The expansion and sugar accumulation of sugar beet root mainly occur in the vegetative stage.Vernalization,as a key factor determining the transition from the vegetative to reproductive growth,is closely related to the reproductive cycle and yield of sugar beet.The histone acetylation modification catalyzed by histone deacetylase（HDAC）,as an important epigenetic regulation,is relevant to the vernalization in winter plants.At present,how histone deacetylases are involved in vernalization in sugar beet is still unclear.In this study,we applied bioinformatics analyze to identify HDAC family of sugar beet.On the basis of HDAC expression patterns during vernalization,HDAC inhibitors（HDACi）were selected and used for investigating its effect on bolting agronomic traits and gene expression in sugar beet treated with different vernalization time.Exploring whether histone deacetylation were involved in regulation of vernalization in sugar beet.The main results of this study are showed as follows:1.In this study,16 members of HDAC family were identified in sugar beet and classified into RPD3/HDA1,SIR2,HD2 subfamily.Based on results of RNA-seq,we found that BvHDAC1,BvHDAC2,BvHDAC5,and BvHDAC6 genes were significantly up-regulated during vernalization.BvSIRT1 belong to SIR2 subfamily was also significantly up-regulated during vernalization.BvHDT1 and BvHDT2 in the HD2 subfamily were significantly down-regulated at 6-10 weeks after vernalization,implying the possible role in time dose of vernalization in sugar beet.Sodium butyrate and nicotinamide were selected to inhibit enzyme activity of RPD3/HDA1 and SIR2 subfamily for following studies.2.The bolting delay（BD）,total bolting length（TBL）and bolting index（BI）were measured in 0,4 and 14 weeks-vernalized sugar beets treated with sodium butyrate or nicotinamide.The results showed that sodium butyrate and nicotinamide failed to induce bolting in beets with inadequate vernalization（0 and 4 weeks of vernalization）.In 14weeks-vernalized beets,sodium butyrate treatment significantly required longer time for bolting than that of control,BI were significantly lower than the control,suggesting that HDACs in RPD3/HDA1 subfamily may be involved in regulation of vernalization.3.The expression changes of bolting-related genes in stem apex and young leaves after HDACi treatment were measured by qRT-PCR.The results showed that sodium butyrate repressed the expression of vernalization pathway genes,such as BvBTC1 and BvFT2 at the stem apex at 14 weeks after vernalization and also repressed the expression of photoperiod pathway genes,such as BvGI and BvELF3,in young leaves.In contrast,sodium butyrate treatment resulted in up-regulation of BvFT2,BvBTC1,and BvGI at 0and 4 weeks of vernalization,implying that the inhibition caused by sodium depending on sufficient vernalization time.Nicotinamide was also able to suppress the expression of BvBTC1,BvFLC,BvBBX19,BvGI,and BvELF3 in sugar beet at 14 weeks after vernalization,which was similar to the expression pattern in response to sodium butyrate.However,nicotinamide could not inhibit the expression of BvFT2 in the stem apex,implying that bolting inhibition caused by sodium butyrate depending on the co-repression of multiple pathway genes.