712 / 2019-05-06 23:18:13

Jasmonate signaling in plants lacking JA-Ile: The discovery of the missing hormone and an ancient JA biosynthesis pathway

Jasmonate, Marchantia, Arabidopsis, Hormone, evolution

全体主题 > Signal Transduction

Jasmonate-Isoleucine (JA-Ile) is a fatty acid-derived phytohormone structurally similar to metazoan prostaglandins, and essential for plant defense and development. A. thaliana has been an excellent model system in identifying the bioactive hormone and elucidating its signal transduction pathway in eudicots. Nonetheless, information in A. thaliana unlikely represents the diversity of this pathway in other plant lineages.
Bryophyte genomes contain conserved sequences for all JA-Ile signaling components, but in contrast to higher plants, lack JA-Ile. I will introduce a new plant model system, the liverwort Marchantia polymorpha, and explain its enormous advantages for research in Plant Molecular Biology. I will also discuss that in spite of 450 million years of independent evolution, the JA-Ile co-receptor COI1/JAZ is functionally conserved between the bryophyte Marchantia polymorpha and A. thaliana. However, this co-receptor perceives and responds to different ligands in each species. Instead of JA-Ile, the ligand of Marchantia MpCOI1 is the JA-Ile precursor dinor-OPDA. Our analysis of the biosynthetic pathway for dinor-OPDA uncovered an ancient OPR3-independent pathway for JA biosynthesis that is widely distributed from Charophycean algae to eudicots. The evolutionary implications of these discoveries will be discussed during the talk.