National Yangling Agricultural Biotechnology & Breeding Center, Shaanxi Key Laboratory of Crop Heterosis, College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China.
Department of Ecological and Environmental Engineering, Yangling Vocational & Technical College, Yangling, Shaanxi, China.
Plant Biol (Stuttg). 2024 Jun;26(4):602-611. doi: 10.1111/plb.13641. Epub 2024 Apr 18.
Seed coat mucilage plays an important role in promoting seed germination under adversity. Previous studies have shown that Arabidopsis thaliana MYB52 (AtMYB52) can positively regulate seed coat mucilage accumulation. However, the role of Brassica napus MYB52 (BnaMYB52) in accumulation of seed coat mucilage and tolerance to osmotic stress during seed germination remains largely unknown. We cloned the BnaA09.MYB52 coding domain sequence from B. napus cv ZS11, identified its conserved protein domains and elucidated its relationship with homologues from a range of plant species. Transgenic plants overexpressing BnaA09.MYB52 in the A. thaliana myb52-1 mutant were generated through Agrobacterium-mediated transformation and used to assess the possible roles of BnaA09.MYB52 in accumulation of seed coat mucilage and tolerance to osmotic stress during seed germination. Subcellular localization and transcriptional activity assays demonstrated that BnaA09.MYB52 functions as a transcription factor. RT-qPCR results indicate that BnaA09.MYB52 is predominantly expressed in roots and developing seeds of B. napus cv ZS11. Introduction of BnaA09.MYB52 into myb52-1 restored thinner seed coat mucilage in this mutant to levels in the wild type. Consistently, expression levels of three key genes participating in mucilage formation in developing seeds of myb52-1 were also restored to wild type levels by overexpressing BnaA09.MYB52. Furthermore, BnaA09.MYB52 was induced by osmotic stress during seed germination in B. napus, and ectopic expression of BnaA09.MYB52 successfully corrected sensitivity of the myb52-1 mutant to osmotic stress during seed germination. These findings enhance our understanding of the functions of BnaA09.MYB52 and provide a novel strategy for future B. napus breeding.
种皮黏液在逆境下促进种子萌发中起着重要作用。先前的研究表明，拟南芥 MYB52（AtMYB52）可以正向调控种皮黏液的积累。然而，油菜 MYB52（BnaMYB52）在种皮黏液积累和种子萌发过程中耐渗胁迫方面的作用在很大程度上仍不清楚。我们从油菜品种 ZS11 克隆了 BnaA09.MYB52 的编码区序列，鉴定了其保守的蛋白质结构域，并阐明了它与一系列植物物种同源物的关系。通过农杆菌介导的转化，将过表达 BnaA09.MYB52 的转基因植物导入到拟南芥 myb52-1 突变体中，用于评估 BnaA09.MYB52 在种皮黏液积累和种子萌发过程中耐渗胁迫方面的可能作用。亚细胞定位和转录活性测定表明，BnaA09.MYB52 作为一个转录因子发挥作用。RT-qPCR 结果表明，BnaA09.MYB52 在油菜品种 ZS11 的根和发育种子中表达丰度较高。将 BnaA09.MYB52 导入到 myb52-1 中，使该突变体中较薄的种皮黏液恢复到野生型水平。一致地，通过过表达 BnaA09.MYB52，也使 myb52-1 发育种子中参与黏液形成的三个关键基因的表达水平恢复到野生型水平。此外，油菜在种子萌发过程中受到渗胁迫的诱导，BnaA09.MYB52 的异位表达成功纠正了 myb52-1 突变体在种子萌发过程中对渗胁迫的敏感性。这些发现增强了我们对 BnaA09.MYB52 功能的理解，并为油菜未来的育种提供了一种新策略。
