State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Chengdu 611130, China.
State Key Laboratory of Hybrid Rice, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, China.
Development. 2021 Mar 21;148(6):dev196378. doi: 10.1242/dev.196378.
Starch accumulation is key for the maturity of rice pollen grains; however, the regulatory mechanism underlying this process remains unknown. Here, we have isolated a male-sterile rice mutant, (), which produces nonviable pollen grains with defective starch accumulation. Functional analysis revealed that encodes an active L-type lectin receptor-like kinase (L-LecRLK). AP1 is localized to the plasma membrane and its transcript is highly accumulated in pollen during the starch synthesis phase. RNA-seq and phosphoproteomic analysis revealed that the expression/phosphorylation levels of numerous genes/proteins involved in starch and sucrose metabolism pathway were significantly altered in the mutant pollen, including a known rice UDP-glucose pyrophosphorylase (OsUGP2). We further found that AP1 physically interacts with OsUGP2 to elevate its enzymatic activity, likely through targeted phosphorylation. These findings revealed a novel role of L-LecRLK in controlling pollen maturity via modulating sucrose and starch metabolism.
淀粉积累是水稻花粉粒成熟的关键；然而，这一过程的调控机制尚不清楚。在这里，我们分离到一个雄性不育的水稻突变体， （），其产生的花粉粒无活力，淀粉积累有缺陷。功能分析表明， 编码一个活性的 L 型凝集素受体样激酶（L-LecRLK）。AP1 定位于质膜，其转录本在花粉发育的淀粉合成阶段高度积累。RNA-seq 和磷酸蛋白质组学分析表明，突变体花粉中参与淀粉和蔗糖代谢途径的许多基因/蛋白的表达/磷酸化水平发生了显著变化，包括已知的水稻 UDP-葡萄糖焦磷酸化酶（OsUGP2）。我们进一步发现，AP1 与 OsUGP2 发生物理相互作用，从而提高其酶活性，可能是通过靶向磷酸化。这些发现揭示了 L-LecRLK 通过调节蔗糖和淀粉代谢来控制花粉成熟的新作用。
