In addition to defense response, phytohormone jasmonate participates in various plant growth and developmental processes. Nonetheless, its role in the seedling stage is not well defined. We recently report that jasmonate suppresses hypocotyl elongation and promotes cotyledon unfolding in etiolated Arabidopsis seedlings. The molecular basis underlying this phenotype is that jasmonate treatment reduces the biochemical activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) to stabilize several COP1-targetted transcription factors for eliciting a proportion of light responsive transcriptome. We further reveal that jasmonate receptor CORONATINE INSENSITIVE 1 (COI1) and bHLH transcription factor MYC2 are required for the suppression of COP1 activity. Because elongated hypocotyl and closed cotyledons secure the success for seedling soil emergence, here we investigate seedling soil emergence under jasmonate treatment and find that jasmonate reduces the seedling emerging rates in the wild-type plants. Consistent with the largely insensitive to jasmonate in the suppression of skotomorphogenesis, the soil emerging rates in coi1 or myc2 mutants are almost not altered in the presence of jasmonate. Our data addendum describe that jasmonate-triggered inhibition of etiolation growth results in the defects in seedling soil emergence and suggest that defense-stimulated jasmonate biosynthesis might affect seedling germination in soil.
Keywords: COP1; MYC2; jasmonate; skotomorphogenesis; soil emergence.