College of Horticulture, South China Agricultural University, Guangzhou, 510642, PR China.
Horticultural Research Institute, Yunnan Academy of Agricultural Science, Kunming, 650231, PR China.
BMC Plant Biol. 2020 Jul 9;20(1):326. doi: 10.1186/s12870-020-02476-3.
The DnaJ proteins play critical roles in plant development and stress responses. Recently, seventy-six DnaJ genes were identified through a comprehensive bioinformatics analysis in the pepper genome. However, there were no reports on understanding of phylogenetic relationships and diverse expression profile of pepper DnaJ genes to date. Herein, we performed the systemic analysis of the phylogenetic relationships and expression profile of pepper DnaJ genes in different tissues and in response to both abiotic stress and plant hormones.
Phylogenetic analysis showed that all the pepper DnaJ genes were grouped into 7 sub-families (sub-family I, II, III, IV, V, VI and VII) according to sequence homology. The expression of pepper DnaJs in different tissues revealed that about 38% (29/76) of pepper DnaJs were expressed in at least one tissue. The results demonstrate the potentially critical role of DnaJs in pepper growth and development. In addition, to gain insight into the expression difference of pepper DnaJ genes in placenta between pungent and non-pungent, their expression patterns were also analyzed using RNA-seq data and qRT-PCR. Comparison analysis revealed that eight genes presented distinct expression profiles in pungent and non-pungent pepper. The CaDnaJs co-expressed with genes involved in capsaicinoids synthesis during placenta development. What is more, our study exposed the fact that these eight DnaJ genes were probably regulated by stress (heat, drought and salt), and were also regulated by plant hormones (ABA, GA3, MeJA and SA).
In summary, these results showed that some DnaJ genes expressed in placenta may be involved in plant response to abiotic stress during biosynthesis of compounds related with pungency. The study provides wide insights to the expression profiles of pepper DanJ genes and contributes to our knowledge about the function of DnaJ genes in pepper.
DnaJ 蛋白在植物发育和应激反应中发挥着关键作用。最近，通过对辣椒基因组的全面生物信息学分析，鉴定出了 76 个 DnaJ 基因。然而，迄今为止，还没有关于辣椒 DnaJ 基因的系统进化关系和多样化表达谱的报道。在此，我们对辣椒 DnaJ 基因在不同组织中的系统进化关系和表达谱进行了分析，并研究了它们对非生物胁迫和植物激素的响应。
系统进化分析表明，根据序列同源性，所有辣椒 DnaJ 基因均分为 7 个亚家族（亚家族 I、II、III、IV、V、VI 和 VII）。不同组织中辣椒 DnaJ 的表达表明，约 38%（29/76）的辣椒 DnaJ 在至少一种组织中表达。结果表明 DnaJ 可能在辣椒生长发育中发挥重要作用。此外，为了深入了解辣味和非辣味辣椒胎盘中 DnaJ 基因的表达差异，我们还使用 RNA-seq 数据和 qRT-PCR 分析了它们的表达模式。比较分析表明，8 个基因在辣味和非辣味辣椒中呈现出不同的表达谱。CaDnaJ 与辣椒素合成相关基因在胎盘中共同表达。更重要的是，我们的研究揭示了这 8 个 DnaJ 基因可能受到胁迫（热、干旱和盐）和植物激素（ABA、GA3、MeJA 和 SA）的调节。
综上所述，这些结果表明，一些在胎盘中表达的 DnaJ 基因可能参与了植物在化合物生物合成过程中对与辣味相关的化合物的生物合成过程中的非生物胁迫反应。本研究为辣椒 DnaJ 基因的表达谱提供了广泛的见解，并有助于我们了解 DnaJ 基因在辣椒中的功能。
