Abscisic acid promotes jasmonic acid biosynthesis via a 'SAPK10-bZIP72-AOC' pathway to synergistically inhibit seed germination in rice (Oryza sativa)

Seed germination is coordinated by diverse phytohormones. Abscisic acid (ABA) and Jasmonic acid (JA) both inhibit seed germination, but their interactions during this process remains elusive. Here, we report the identification of a “SAPK10-bZIP72-AOC” module, through which ABA promotes JA biosynthesis to synergistically inhibit rice seed germination. In reception of ABA signal, SAPK10 exhibits auto-phosphorylation activity on the 177^th serine, which enables it to phosphorylate bZIP72 majorly on 71^st serine. The SAPK10-dependent phosphorylation enhances bZIP72 protein stability as well as the DNA binding ability to the G-box cis-element of AOC promoter, thus to elevate the AOC transcription and endogenous JA level to synergistically inhibit seed germination. Blocking of JA biosynthesis or signaling significantly alleviated the ABA sensitivity on seed germination, suggesting that ABA-imposed inhibition is partially relied on the elevated JA level. Our findings shed deeper insight into the molecular networks of ABA-JA synergistic interaction during rice seed germination.

What will audience learn from your presentation?

• The current study identified a key ABA signaling pathway ‘SAPK10-bZIP72-AOC’ in rice seed germination.
• The current works uncovered the comprehensive effects of SAPK10-mediated phosphorylation on the ABA signaling elements.
• e concluded that the inhibition effect of ABA in seed germination is partially based on the activated JA concentration.
• Our findings shed a novel insight into the molecular networks of ABA–JA synergistic interaction during rice seed germination.