Page 12 - S. Plant biology

[S. Plant biology-7]

FIBRILLIN2 is required to photoprotection in high-light and

jasmonate-induced senescence in Arabidopsis

Inyoung Kim¹, Hyun Uk Kim¹˙²˙*

¹Molecular Biology, Sejong university, Seoul 05006, Republic of Korea, ²Bioindustry and Bioresource Engineering,

Sejong university, Seoul 05006, Republic of Korea

FIBRILLINS (FBNs) are major structural proteins of plastoglobule (PG) in chloroplast. PG is associated with defense
against abiotic or biotic stress as well as lipid storage. Even though FBN2 is abundant component in PG, the

independent function of FBN2 have not been identified under the abiotic stress. In this study, FBN2 gene showed

higher expression in green photosynthetic tissues than other non-green tissues and upregulated transcription level
under high-light stress. The photosynthesis capacity in fbn2 knockout mutants rapidly decreased than wild-type
plants under the high-light stress and both plastoquinone-9 (PQ-9) and plastochromanol-8 (PC-8), which has been

known as an antioxidant to inhibit oxidation of the thylakoid membrane, decreased in fbn2 mutants. In addition,
the fbn2 mutants were highly sensitive to methyl jasmonate (MeJA), showing root growth inhibition and pale green

phenotype due to reduced chlorophyll content. Consistently, the fbn2 mutation showed faster senescence and rapid
chlorophyll degradation with decrease of photosynthetic ability than wild-type plants by treatment of MeJA

combined with dark. These results suggest that FBN2 is involved in light protection under high-light stress and acts
as an inhibitor of JA-induced senescence in Arabidopsis.