College of Horticulture, China Agricultural University, Beijing, 100193, China.
College of Horticulture, China Agricultural University, Beijing, 100193, China; State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
J Plant Physiol. 2023 Apr;283:153965. doi: 10.1016/j.jplph.2023.153965. Epub 2023 Mar 5.
Drought is the most prominent threat to global agricultural production. The basic leucine zipper (bZIP) family is related to the response to a series of abiotic stress. In this case, apple calli and the seedlings of MdbZIP74-RNAi transgenic lines were obtained. Under osmotic stress and moderate drought conditions, the content of malondialdehyde, relative water content and other stress-related assays were measured. MdbZIP74 was found to negatively regulate the osmotic tolerance of apple callus. The growth of MdbZIP74-RNAi calli enhanced resistance without significant production loss. The silencing of MdbZIP74 contributes to redox balance and the adaptability of apple seedlings to moderate drought conditions. Four related differentially expressed genes in the biosynthesis of cytokinin and catabolic pathway were identified through a transcriptome analysis of MdbZIP74-RNAi seedlings under moderate drought conditions. MdLOG8 was further identified as the target of MdbZIP74 involved in the drought adaptability of apple plants using a dual experiment. Further confirmation showed MdLOG8 was maintained in the MdbZIP74-RNAi seedlings presumably acting as the growth regulator to enhance drought adaptability. It was concluded that the correct regulation of cytokinin level under moderate drought conditions maintains the redox balance and avoids the situation of plants surviving with the minimal resources.
干旱是全球农业生产面临的最突出威胁。碱性亮氨酸拉链（bZIP）家族与一系列非生物胁迫的响应有关。本研究中，获得了苹果愈伤组织和 MdbZIP74-RNAi 转基因苗。在渗透胁迫和适度干旱条件下，测量了丙二醛含量、相对水含量等应激相关指标。发现 MdbZIP74 负调控苹果愈伤组织的渗透耐受性。MdbZIP74-RNAi 愈伤组织的生长增强了抗性，而不会显著降低产量。MdbZIP74 的沉默有助于苹果幼苗的氧化还原平衡和适应适度干旱条件。通过对中度干旱条件下 MdbZIP74-RNAi 幼苗的转录组分析，鉴定了与细胞分裂素生物合成和分解代谢途径相关的四个差异表达基因。通过双实验进一步鉴定 MdLOG8 是 MdbZIP74 参与苹果植物耐旱性的靶标。进一步的验证表明，MdLOG8 在 MdbZIP74-RNAi 幼苗中得以维持，可能作为生长调节剂增强耐旱性。结论是，在适度干旱条件下正确调节细胞分裂素水平可维持氧化还原平衡，并避免植物以最小资源生存的情况。
