State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
China MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China.
Plant Cell Physiol. 2022 Jul 14;63(7):967-980. doi: 10.1093/pcp/pcac061.
Plant High-affinity K+ transporters/K+ uptake permeases/K+ transporters (HAK/KUP/KT) transporters have been predicted as membrane H+-K+ symporters in facilitating K+ uptake and distribution, while their role in seed production remains to be elucidated. In this study, we report that OsHAK26 is preferentially expressed in anthers and seed husks and located in the Golgi apparatus. Knockout of either OsHAK26 or plasma membrane located H+-K+ symporter gene OsHAK1 or OsHAK5 in both Nipponbare and Dongjin cultivars caused distorted anthers, reduced number and germination rate of pollen grains. Seed-setting rate assay by reciprocal cross-pollination between the mutants of oshak26, oshak1, oshak5 and their wild types confirmed that each HAK transporter is foremost for pollen viability, seed-setting and grain yield. Intriguingly, the pollens of oshak26 showed much thinner wall and were more vulnerable to desiccation than those of oshak1 or oshak5. In vitro assay revealed that the pollen germination rate of oshak5 was dramatically affected by external K+ concentration. The results suggest that the role of OsHAK26 in maintaining pollen development and fertility may relate to its proper cargo sorting for construction of pollen walls, while the role of OsHAK1 and OsHAK5 in maintaining seed production likely relates to their transcellular K+ transport activity.
植物高亲和力 K+转运体/K+摄取渗透酶/K+转运体（HAK/KUP/KT）转运体被预测为膜 H+-K+协同转运体，有助于 K+的摄取和分布，而其在种子生产中的作用仍有待阐明。在这项研究中，我们报告说，OsHAK26 在花药和种皮中优先表达，位于高尔基体中。敲除 Nipponbare 和 Dongjin 品种中的 OsHAK26 或质膜定位的 H+-K+协同转运体基因 OsHAK1 或 OsHAK5，都会导致花药畸形，花粉粒数量和萌发率降低。通过对 oshak26、oshak1、oshak5 及其野生型突变体进行正反交授粉的结实率测定，证实每个 HAK 转运体对花粉活力、结实率和籽粒产量都是首要的。有趣的是，oshak26 的花粉壁更薄，比 oshak1 或 oshak5 的花粉更容易干燥。体外试验表明，外源 K+浓度对 oshak5 的花粉萌发率有显著影响。结果表明，OsHAK26 在维持花粉发育和育性中的作用可能与其对花粉壁构建的适当货物分拣有关，而 OsHAK1 和 OsHAK5 在维持种子生产中的作用可能与其跨细胞 K+转运活性有关。
