Polyploids have elevated stress tolerance, but the underlying mechanisms remain largely elusive. In this study, we showed that naturally occurring tetraploid plants of trifoliate orange (Poncirus tri-foliata (L.) Raf.) exhibited enhanced cold tolerance relative to their diploid progenitors. Transcriptome analysis revealed that whole-genome duplication was associated with higher expression levels of a range of well-characterized cold stress-responsive genes. Global DNA methylation profiling demon-strated that the tetraploids underwent more ex-tensive DNA demethylation in comparison with the diploids under cold stress. CHH methylation in the promoters was associated with up-regulation of related genes, whereas CG, CHG, and CHH methylation in the 3'-regions was relevant to gene down-regulation. Of note, genes involved in un-saturated fatty acids (UFAs) and jasmonate (JA) biosynthesis in the tetraploids displayed different CHH methylation in the gene flanking regions and were prominently up-regulated, consistent with greater accumulation of UFAs and JA when ex-posed to the cold stress. Collectively, our findings explored the difference in cold stress response between diploids and tetraploids at both tran-scriptional and epigenetic levels, and gained new insight into the molecular mechanisms underlying enhanced cold tolerance of the tetraploid. These results contribute to uncovering a novel regulatory role of DNA methylation in better cold tolerance of polyploids.

Yue Wang;Lanlan Zuo;Tonglu Wei;Yu Zhang;Yang Zhang;Ruhong Ming;Dahro Bachar;Wei Xiao;Khan Madiha;Chuanwu Chen;Qijun Fan;Chunlong Li;Ji-Hong Liu

Key Laboratory of Horticultural Plant Biology(MOE),College of Horticulture and Forestry Sciences,Huazhong Agricultural University,Wuhan 430070,China;Guangxi Key Laboratory of Citrus Biology,Guangxi Academy of Specialty Crops,Guilin 541004,China

植物学报（英文版）

[1]Yue Wang;Lanlan Zuo;Tonglu Wei;Yu Zhang;Yang Zhang;Ruhong Ming;Dahro Bachar;Wei Xiao;Khan Madiha;Chuanwu Chen;Qijun Fan;Chunlong Li;Ji-Hong Liu-.CHH methylation of genes associated with fatty acid and jasmonate biosynthesis contributes to cold tolerance in autotetraploids of Poncirus trifoliataFA)[J].植物学报（英文版）,2022(12):2327-2343

autotetraploids,trifoliataFA,Polyploids,foliata,polyploids

CHH,genes,associated,fatty,jasmonate,biosynthesis,contributes,cold,tolerance,Poncirus,have,elevated,stress,underlying,mechanisms,remain,largely,elusive,In,this,study,showed,that,naturally,occurring,plants,trifoliate,orange,Raf,exhibited,enhanced,relative,their,progenitors,Transcriptome,analysis,revealed,whole,genome,duplication,was,higher,expression,levels,well,characterized,responsive,Global,profiling,demon,strated,underwent,more,tensive,demethylation,comparison,diploids,promoters,regulation,related,whereas,CG,CHG,regions,relevant,down,Of,note,involved,saturated,acids,UFAs,JA,displayed,different,flanking,were,prominently,regulated,consistent,greater,accumulation,when,posed,Collectively,our,findings,explored,difference,response,between,both,tran,scriptional,epigenetic,gained,new,insight,into,molecular,These,results,uncovering,novel,regulatory,role,better

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