Tan Bin, Yan Liu, Li Huannan, Lian Xiaodong, Cheng Jun, Wang Wei, Zheng Xianbo, Wang Xiaobei, Li Jidong, Ye Xia, Zhang Langlang, Li Zhiqian, Feng Jiancan
College of Horticulture, Henan Agricultural University, Zhengzhou, China.
Henan Key Laboratory of Fruit and Cucurbit Biology, Zhengzhou, China.
PeerJ. 2021 Mar 12;9:e10961. doi: 10.7717/peerj.10961. eCollection 2021.
Heat shock factors (HSFs) play important roles during normal plant growth and development and when plants respond to diverse stressors. Although most studies have focused on the involvement of HSFs in the response to abiotic stresses, especially in model plants, there is little research on their participation in plant growth and development or on the HSF (PpHSF) gene family in peach ().
DBD (PF00447), the HSF characteristic domain, was used to search the peach genome and identify . Phylogenetic, multiple alignment and motif analyses were conducted using MEGA 6.0, ClustalW and MEME, respectively. The function of was confirmed by overexpression of into Arabidopsis.
Eighteen genes were identified within the peach genome. The genes were nonuniformly distributed on the peach chromosomes. Seventeen of the (94.4%) contained one or two introns, except , which contained three introns. The in silico-translated PpHSFs were classified into three classes (PpHSFA, PpHSFB and PpHSFC) based on multiple alignment, motif analysis and phylogenetic comparison with HSFs from and . Dispersed gene duplication (DSD at 67%) mainly contributed to HSF gene family expansion in peach. Promoter analysis showed that the most common cis-elements were the MYB (abiotic stress response), ABRE (ABA-responsive) and MYC (dehydration-responsive) elements. Transcript profiling of 18 showed that the expression trend of was consistent with shoot length changes in the cultivar 'Zhongyoutao 14'. Further analysis of the was conducted in 5-year-old peach trees, and , respectively. Tissue-specific expression analysis showed that was expressed predominantly in young vegetative organs (leaf and apex). Subcellular localization revealed that PpHSF5 was located in the nucleus in cells. Two transgenic Arabidopsis lines were obtained that overexpressed . The root length and the number of lateral roots in the transgenic seedlings were significantly less than in WT seedlings and after cultivation for three weeks. The transgenic rosettes were smaller than those of the WT at 2-3 weeks. The two transgenic lines exhibited a dwarf phenotype three weeks after transplanting, although there was no significant difference in the number of internodes. Moreover, the PpHSF5-OE lines exhibited enhanced thermotolerance. These results indicated that PpHSF5 might be act as a suppresser of growth and development of root and aerial organs.
热激因子（HSFs）在植物正常生长发育以及植物对多种胁迫的响应过程中发挥着重要作用。尽管大多数研究集中于HSFs参与非生物胁迫响应，尤其是在模式植物中，但关于它们参与植物生长发育的研究以及桃（PpHSF）基因家族的研究却很少。
利用HSF特征结构域DBD（PF00447）搜索桃基因组并鉴定PpHSFs。分别使用MEGA 6.0、ClustalW和MEME进行系统发育、多序列比对和基序分析。通过将PpHSF5过表达至拟南芥中来确认其功能。
在桃基因组中鉴定出18个PpHSF基因。这些PpHSF基因在桃染色体上分布不均。18个基因中的17个（94.4%）含有1个或2个内含子，只有PpHSF3含有3个内含子。基于多序列比对、基序分析以及与拟南芥和番茄中HSFs的系统发育比较，通过计算机翻译的PpHSFs被分为三类（PpHSFA、PpHSFB和PpHSFC）。分散基因复制（DSD，占67%）是桃HSF基因家族扩张的主要原因。启动子分析表明，最常见的顺式作用元件是MYB（非生物胁迫响应）、ABRE（脱落酸响应）和MYC（脱水响应）元件。18个PpHSF基因的转录谱分析表明，PpHSF5的表达趋势与‘中油桃14’品种新梢长度变化一致。分别在5年生桃树、中油桃14和中油桃16中对PpHSF5进行了进一步分析。组织特异性表达分析表明，PpHSF5主要在幼嫩营养器官（叶片和顶端）中表达。亚细胞定位显示，PpHSF5定位于烟草细胞的细胞核中。获得了两个过表达PpHSF5的转基因拟南芥株系。转基因幼苗的根长和侧根数量显著少于野生型幼苗，培养三周后也是如此。在2 - 3周龄时，转基因莲座叶比野生型的小。移栽三周后，两个转基因株系表现出矮化表型，尽管节间数量没有显著差异。此外，PpHSF5过表达株系表现出增强的耐热性。这些结果表明，PpHSF5可能是根和地上器官生长发育的抑制因子。
