Abstract：
Heat shock protein 70s (HSP70s) are highly conserved proteins that are involved in stress responses. These chaperones play pivotal roles in protein folding, removing the extra amounts of oxidized proteins, preventing protein denaturation, and improving the antioxidant system activities. This conserved family has been characterized in several crops under drought stress conditions. However, there is no study on HSP70s in pumpkin (Cucurbita moschata). Therefore, we performed a comprehensive analysis of this gene family, including phylogenetic relationship, motif and gene structure analysis, gene duplication, collinearity, and promoter analysis. In this research, we found 21 HSP70s that were classified into five groups (from A to E). These genes were mostly localized in the cytoplasm, chloroplast, mitochondria, nucleus, and endoplasmic reticulum (ER). We could observe more similarity in closely linked subfamilies in terms of motifs, the number of introns/exons, and the corresponding cellular compartments. According to the collinearity analysis, gene duplication had occurred as a result of purifying selection. The results showed that the occurrence of gene duplication for all nine gene pairs was due to segmental duplication (SD). Synteny analysis revealed a closer relationship between pumpkin and cucumber than pumpkin and Arabidopsis. Promoter analysis showed the presence of various cis-regulatory elements in the up-stream region of the HSP70 genes, such as hormones and stress-responsive elements, indicating a potential role of this gene family in stress tolerance. We furtherly performed the gene expression analysis of the HSP70s in pumpkin under progressive drought stress. Pumpkin is widely used as a rootstock to improve stress tolerance, as well as fruit quality of cucumber scion. Since stress-responsive mobile molecules translocate through vascular tissue from roots to the whole plant body, we used the xylem of grafted materials to study the expression patterns of the HSP70 (potentially mobile) gene family. The results indicated that all CmoHSP70s had very low expression levels at 4 days after stress (DAS). However, the genes showed different expression patterns by progressing he drought period. For example, the expression of CmoHSP70-4 (in subgroup E) and CmoHSP70-14 (in subgroup C) sharply increased at 6 and 11 DAS, respectively. However, the expression of all genes belonging to subgroup A did not change significantly in response to drought stress. These findings indicated the diverse roles of this gene family under drought stress and provided valuable information for further investigation on the function of this gene family, especially under stressful conditions.
摘要：
热休克蛋白70s(HSP70s)是参与应激反应的高度保守蛋白。这些伴侣在蛋白质折叠中起关键作用，去除多余的氧化蛋白质，防止蛋白质变性，提高抗氧化系统的活性。在干旱胁迫条件下，这种保守的家庭已在几种作物中得到表征。然而,没有关于南瓜（南瓜）中HSP70s的研究。因此,我们对这个基因家族进行了全面的分析，包括系统发育关系，基序和基因结构分析，基因复制，共线性,和启动子分析。在这项研究中,我们发现21个HSP70s分为五组(从A到E)。这些基因大多位于细胞质中，叶绿体，线粒体,核，和内质网（ER）。我们可以观察到紧密相连的亚家族在基序方面有更多的相似性，内含子/外显子的数量，和相应的细胞区室。根据共线性分析，由于纯化选择，发生了基因重复。结果表明，所有9个基因对的基因复制的发生都是由于节段复制（SD）。综合分析显示，南瓜和黄瓜之间的关系比南瓜和拟南芥更紧密。启动子分析显示HSP70基因的上游区域存在各种顺式调节元件，比如荷尔蒙和应激反应的元素，表明该基因家族在胁迫耐受性中的潜在作用。我们进一步进行了渐进干旱胁迫下南瓜中HSP70的基因表达分析。南瓜被广泛用作砧木，以提高抗逆性，以及黄瓜接穗的果实品质。由于应激反应的移动分子通过血管组织从根部转移到整个植物体内，我们使用嫁接材料的木质部研究HSP70（潜在移动）基因家族的表达模式。结果表明,所有CmoHSP70s在应激(DAS)后4天具有非常低的表达水平。然而,随着干旱期的发展，这些基因表现出不同的表达模式。例如,CmoHSP70-4（在E亚组中）和CmoHSP70-14（在C亚组中）的表达在6和11DAS时急剧增加，分别。然而,属于A亚组的所有基因的表达在响应干旱胁迫时没有显着变化。这些发现表明了该基因家族在干旱胁迫下的不同作用，为进一步研究该基因家族的功能提供了有价值的信息。尤其是在紧张的条件下。
