Recently, researchers from the Rice Research Institute of the Guangdong Academy of Agricultural Sciences have made significant progress in studying the mechanism of rice seed germination. The relevant findings have been published in the journal "Rice."
Panicle germination (also known as panicle sprouting or pre-harvest sprouting) refers to the phenomenon of seeds germinating on the mother plant before harvest. In China, the annual loss rate caused by panicle germination in rice production exceeds 5%. With the increase in global warming and abnormal climate phenomena, the damage caused by panicle germination is becoming increasingly severe. Improving resistance to panicle germination is one of the important goals of rice breeding.
In their previous research, the team found that overexpression of OsMKKK62 (Mitogen-Activated Protein Kinase Kinase Kinase 62) leads to severe panicle germination in rice and proposed the MKK3 cascade (OsMKKK62-OsMKK3-OsMPK7/14, where OsMKKK62 phosphorylates OsMKK3, which in turn phosphorylates OsMPK7/14), which positively regulates seed germination.
Through experimental validation of OsMKK3 overexpression, this study confirmed the strong promotion effect of the MKK3 cascade on germination, further confirming the previous speculation. Based on the expression changes of the ABA (Abscisic Acid) responsive gene OsMFT2 (Mother of FT and TFL1 2), it is speculated that the MKK3 cascade may participate in ABA signaling. Biochemical experiments confirmed the interaction between OsMPK7 and multiple ABA signaling core components; physiological and gene expression experiments also confirmed that during germination, the MKK3 cascade negatively regulates ABA signaling.
Based on these results, the MKK3 cascade may play a role in the ABA signaling clearance system. This study proposes that the MKK3 cascade negatively regulates ABA signaling by interacting with core ABA signaling components, affecting seed germination. Since members of the MKK3 cascade are abundantly expressed in other tissues of rice, this cascade may be an important component of the ABA signaling system, with implications for the study of plant ABA signaling.
Related Paper Information: https://doi.org/10.1186/s12284-023-00679-4
