Sun Jin, Chen Jiaqi, Si Xinyu, Liu Weikang, Yuan Mingzhu, Guo Shirong, Wang Yu
College of Horticulture, Nanjing Agricultural University, Nanjing, China.
Front Plant Sci. 2022 Sep 8;13:1012439. doi: 10.3389/fpls.2022.1012439. eCollection 2022.
Grafting is one of the key agronomic measures to enhance the tolerance to environmental stresses in horticultural plants, but the specific molecular regulation mechanism in this tolerance largely remains unclear. Here, we found that cucumber grafted onto figleaf gourd rootstock increased cold tolerance through abscisic acid (ABA) activating WRKY41/WRKY46-miR396b-5p-TPR (tetratricopeptide repeat-like superfamily protein) module. Cucumber seedlings grafted onto figleaf gourd increased cold tolerance and induced the expression of miR396b-5p. Furthermore, overexpression of cucumber miR396b-5p in Arabidopsis improved cold tolerance. 5' RNA ligase-mediated rapid amplification of cDNA ends (5' RLM-RACE) and transient transformation experiments demonstrated that was the target gene of miR396b-5p, while overexpression plants were hypersensitive to cold stress. The yeast one-hybrid and dual-luciferase assays showed that both WRKY41 and WRKY46 bound to promoter to induce its expression. Furthermore, cold stress enhanced the content of ABA in the roots and leaves of figleaf gourd grafted cucumber seedlings. Exogenous application of ABA induced the expression of and , and cold tolerance of grafted cucumber seedlings. However, figleaf gourd rootstock-induced cold tolerance was compromised when plants were pretreated with ABA biosynthesis inhibitor. Thus, ABA mediated figleaf gourd grafting-induced cold tolerance of cucumber seedlings through activating the WRKY41/WRKY46-miR396b-5p- module.
嫁接是增强园艺植物对环境胁迫耐受性的关键农艺措施之一，但这种耐受性的具体分子调控机制在很大程度上仍不清楚。在此，我们发现嫁接到黑籽南瓜砧木上的黄瓜通过脱落酸（ABA）激活WRKY41/WRKY46-miR396b-5p-TPR（四肽重复样超家族蛋白）模块提高了耐寒性。嫁接到黑籽南瓜上的黄瓜幼苗提高了耐寒性并诱导了miR396b-5p的表达。此外，拟南芥中黄瓜miR396b-5p的过表达提高了耐寒性。5'RNA连接酶介导的cDNA末端快速扩增（5'RLM-RACE）和瞬时转化实验表明， 是miR396b-5p的靶基因，而过表达 植株对冷胁迫高度敏感。酵母单杂交和双荧光素酶实验表明，WRKY41和WRKY46均与 启动子结合以诱导其表达。此外，冷胁迫提高了嫁接到黑籽南瓜的黄瓜幼苗根和叶中ABA的含量。外源施用ABA诱导了 和 的表达以及嫁接黄瓜幼苗的耐寒性。然而，当用ABA生物合成抑制剂预处理植株时，黑籽南瓜砧木诱导的耐寒性受到损害。因此，ABA通过激活WRKY41/WRKY46-miR396b-5p- 模块介导黑籽南瓜嫁接诱导的黄瓜幼苗耐寒性。
