Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, Japan.
Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, Okayama, Japan.
J Exp Bot. 2019 Oct 24;70(20):5745-5751. doi: 10.1093/jxb/erz343.
Commercial seeds of Brassicaceae vegetable crops are mostly F1 hybrids, the production of which depends on self-incompatibility during pollination. Self-incompatibility is known to be weakened by exposure to elevated temperatures, which may compromise future breeding and seed production. In the Brassicaceae, self-incompatibility is controlled by two genes, SRK and SCR, which function as female and male determinants of recognition specificity, respectively. However, the molecular mechanisms underlying the breakdown of self-incompatibility under high temperature are poorly understood. In this study, we examined the self-incompatibility phenotypes of self-incompatible Arabidopsis thaliana SRK-SCR transformants under normal (23 °C) and elevated (29 °C) temperatures. Exposure to elevated temperature caused defects in the stigmatic, but not the pollen, self-incompatibility response. In addition, differences in the response to elevated temperature were observed among different S haplotypes. Subcellular localization revealed that high temperature disrupted the targeting of SRK to the plasma membrane. SRK localization in plants transformed with different S haplotypes corresponded to their self-incompatibility phenotypes, further indicating that defects in SRK localization were responsible for the breakdown in the self-incompatibility response at high temperature. Our results provide new insights into the causes of instability in self-incompatibility phenotypes.
十字花科蔬菜作物的商业种子大多是 F1 杂种，其生产依赖于授粉过程中的自交不亲和性。已知自交不亲和性会因高温暴露而减弱，这可能会影响未来的繁殖和种子生产。在十字花科植物中，自交不亲和性由两个基因 SRK 和 SCR 控制，它们分别作为雌性和雄性识别特异性的决定因素。然而，高温下自交不亲和性打破的分子机制还知之甚少。在这项研究中，我们在正常（23°C）和高温（29°C）条件下检查了自交不亲和拟南芥 SRK-SCR 转化体的自交不亲和表型。高温暴露导致柱头而非花粉的自交不亲和反应出现缺陷。此外，不同 S 单倍型对高温的反应存在差异。亚细胞定位显示高温破坏了 SRK 向质膜的靶向。用不同 S 单倍型转化的植物中 SRK 的定位与它们的自交不亲和表型相对应，进一步表明 SRK 定位的缺陷是高温下自交不亲和反应中断的原因。我们的研究结果为自交不亲和表型不稳定的原因提供了新的见解。
