火龙果HubHLH基因家族的全基因组分析及其对冬季补光诱导开花的表达响应

Whole-genome analysis of the HubHLH gene family in Pitaya and its differential expression in response to supplementary light-induced flowering in winter

为了获得较完整的候选基因,探讨HubHLH基因在火龙果(Hylocereus undatus)冬季补光诱导开花过程的表达响应,对火龙果HubHLH基因家族进行全基因组分析。鉴定出153个HubHLH基因;这些基因的编码蛋白含有176~687个氨基酸,分子量大小为19.28~74.44 kDa,等电点(pI)为4.81~9.88,均为亲水蛋白,亚细胞定位预测大多定位到细胞核。为鉴定HubHLH基因家族的同源性,本研究将153个火龙果HubHLH和120个拟南芥AtbHLH蛋白进行系统发育比较分析。系统发育比较分析结果:火龙果HubHLH基因家族成员被分为12个组,25个亚族;对HubHLH基因家族的保守motif、基因结构及在染色体的位置分布的分析结果表明,同一亚族的基因具有相似的基序组成和基因结构。对HubHLH基因家族的内部复制事件的分析结果表明,有78条片段复制被鉴定为片段重复基因,说明片段复制是HubHLH基因家族的主要扩张力量。此外,基于已测定的关于火龙果冬季补光诱导开花的4个时期转录组数据,筛选到59个HubHLH基因在冬季补光诱导成花过程中有差异表达,随后对这59个HubHLH基因进行GO功能富集,发现它们在红光或远红光的反应、对光刺激的反应、有性生殖功能、对辐射的反应等功能上均有富集,说明HubHLH基因家族可能在冬季补光诱导火龙果成花过程中起到了调控作用。

In order to obtain relative complete candidate genes,the HubHLH gene expression response in Pitaya during the flowering process induced by supplementary light in winter was investigated,and the whole genome of HubHLH gene family in Pitaya was analyzed.There were 153 pitaya HubHLH genes identified,and their encoding proteins contained 176-687 amino acids with their molecular weight being 19.28–74.44 kDa,pI 4.81-9.88.These proteins were all hydrophilic.The prediction of subcellular localization showed that most of the proteins were localized in the nucleus.The pitaya HubHLH proteins were compared with 120 Arabidopsis AtbHLH proteins for phylogenetic analysis.Phylogenetic analysis showed that the pitaya HubHLH proteins were divided into 12 groups and 25 subfamilies.Analysis of conserved motif,gene structure and location distribution in chromosomes showed that genes of the same subfamily had similar motif composition and gene structure.Analysis of the internal replication events of the pitaya HubHLH gene family found that 78 genes were identified as fragment repeating genes,indicating that fragment replication was the main expansion force of the pitaya HubHLH gene family.In addition,based on the transcriptomic data of the four phases of supplementary light-induced flowering of Pitaya in winter,59 HubHLH genes were differentially expressed during the process of supplementary light induced flowering in winter.GO function enrichment showed that they were enriched in response to red or far-red light,light stimulation,sexual reproduction function,and radiation.The HubHLH gene family may play a regulatory role in the flowering process of Pitaya induced by supplementary light in winter.In this study,we conducted a comprehensive genome analysis of the HubHLH gene family in Pitaya,obtained relatively complete candidate genes,and preliminarily investigated the expression response of HubHLH genes in the winter flowering process induced by supplementary light in Pitaya.