Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China) Huazhong Agricultural University, Wuhan, China.
J Exp Bot. 2021 Feb 27;72(5):1677-1690. doi: 10.1093/jxb/eraa564.
Seed germination is a critical stage in the plant life cycle and it plays an important role in the efficiency of agricultural production. However, our knowledge of the mechanisms that regulate seed germination remains limited. In this study, we identified a novel gene, MAPK11, that encodes mitogen-activated protein kinase 11; its expression was significantly higher in seeds of tomato varieties with a low optimum germination temperature than in those with a high optimum germination temperature. In tests at 25 °C, overexpression of MAPK11 in an accession with optimum germination at 25 °C resulted in a decrease in germination, whereas RNAi of MAPK11 in an accession with optimum germination at 15 °C resulted in increased germination. Furthermore, we found that lines overexpressing MAPK11 exhibited hypersensitivity to ABA during germination. These observations were at least partially explained by the fact that MAPK11 up-regulated both NCED1 expression and ABA biosynthesis, and that it also affected ABA signaling and negatively regulated germination by influencing the phosphorylation of SnRK2.2 in vivo. In addition, we found that MAPK11 interacts with and phosphorylates SnRK1 in vivo, thereby potentially inhibiting its activation. SnRK1 interacted with ABI5 and suppressed the transcription of ABI5, thereby affecting ABA signaling and the regulation of germination. Our results demonstrate that ABA signaling in tomato is affected by a mechanism that depends on MAPK11 phosphorylating SnRKs, and this ultimately influences seed germination.
种子萌发是植物生命周期中的一个关键阶段，它在农业生产效率中起着重要作用。然而，我们对调控种子萌发的机制的了解仍然有限。在这项研究中，我们鉴定了一个新的基因 MAPK11，它编码丝裂原活化蛋白激酶 11；其表达在最佳萌发温度较低的番茄品种种子中明显高于最佳萌发温度较高的品种。在 25°C 的测试中，在最佳萌发温度为 25°C 的品种中过表达 MAPK11 导致萌发率降低，而在最佳萌发温度为 15°C 的品种中 RNAi 沉默 MAPK11 导致萌发率增加。此外，我们发现过表达 MAPK11 的系表现出对 ABA 在萌发过程中的超敏反应。这些观察结果至少部分可以解释为 MAPK11 上调了 NCED1 表达和 ABA 生物合成，并且还通过影响体内 SnRK2.2 的磷酸化来影响 ABA 信号传导并负调控萌发。此外，我们发现 MAPK11 在体内与 SnRK1 相互作用并磷酸化 SnRK1，从而潜在地抑制其激活。SnRK1 与 ABI5 相互作用并抑制 ABI5 的转录，从而影响 ABA 信号传导和萌发的调控。我们的结果表明，番茄中的 ABA 信号传导受一种依赖于 MAPK11 磷酸化 SnRKs 的机制影响，这最终影响种子萌发。
