State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
Plant J. 2013 Nov;76(4):687-98. doi: 10.1111/tpj.12328. Epub 2013 Oct 15.
Seed germination and innate immunity both have significant effects on plant life spans because they control the plant's entry into the ecosystem and provide defenses against various external stresses, respectively. Much ecological evidence has shown that seeds with high vigor are generally more tolerant of various environmental stimuli in the field than those with low vigor. However, there is little genetic evidence linking germination and immunity in plants. Here, we show that the rice lectin receptor-like kinase OslecRK contributes to both seed germination and plant innate immunity. We demonstrate that knocking down the OslecRK gene depresses the expression of α-amylase genes, reducing seed viability and thereby decreasing the rate of seed germination. Moreover, it also inhibits the expression of defense genes, and so reduces the resistance of rice plants to fungal and bacterial pathogens as well as herbivorous insects. Yeast two-hybrid and co-immunoprecipitation experiments revealed that OslecRK interacts with an actin-depolymerizing factor (ADF) in vivo via its kinase domain. Moreover, the rice adf mutant exhibited a reduced seed germination rate due to the suppression of α-amylase gene expression. This mutant also exhibited depressed immune responses and reduced resistance to biotic stresses. Our results thus provide direct genetic evidence for a common physiological pathway connecting germination and immunity in plants. They also partially explain the common observation that high-vigor seeds often perform well in the field. The dual effects of OslecRK may be indicative of progressive adaptive evolution in rice.
种子萌发和先天免疫都对植物寿命有重要影响，因为它们分别控制着植物进入生态系统的过程和提供抵御各种外部胁迫的防御能力。大量生态学证据表明，活力较高的种子通常比活力较低的种子更能耐受野外各种环境刺激。然而，很少有遗传证据将植物的萌发和免疫联系起来。在这里，我们发现水稻凝集素受体样激酶 OslecRK 有助于种子萌发和植物先天免疫。我们证明，敲低 OslecRK 基因会抑制α-淀粉酶基因的表达，降低种子活力，从而降低种子萌发率。此外，它还抑制防御基因的表达，从而降低水稻植株对真菌和细菌病原体以及草食性昆虫的抗性。酵母双杂交和共免疫沉淀实验表明，OslecRK 通过其激酶结构域与肌动蛋白解聚因子 (ADF) 在体内相互作用。此外，由于α-淀粉酶基因表达的抑制，水稻 adf 突变体的种子萌发率降低。该突变体还表现出免疫反应减弱和对生物胁迫的抗性降低。我们的研究结果为连接植物萌发和免疫的共同生理途径提供了直接的遗传证据。它们还部分解释了一个常见的观察结果，即高活力种子在野外通常表现良好。OslecRK 的双重作用可能表明水稻的适应性进化在不断推进。
