Summary
Jasmonic acid (JA) signalling has been well studied in Arabidopsis. Most
reports focus on the role of JA in biological pathways such as stress
resistance, trichome initiation and anthocyanin accumulation. The JASMONATE
ZIM-DOMAIN (JAZ) protein is one of the important repressors in the JA
signalling pathway. Previous studies showed that JA functions in fiber
initiation and elongation, but little is known about how JAZ genes function in fiber development.
In this study, a cotton JAZ protein (GhJAZ2) containing a highly conserved TIFY
motif and a C-terminal Jas domain was identified, and its function during
cotton fiber development was analysed. Gene expression analysis showed that GhJAZ2 was preferentially expressed in the
root, hypocotyl, flower and ovule one day before anthesis. Overexpression of GhJAZ2inhibited
both lint and fuzz fiber initiation and reduced the fiber length. Yeast
two-hybrid assays showed that GhJAZ2 interacted with the R2R3-MYB transcription
factors GhMYB25-like and GhGL1, the bHLH transcription factor GhMYC2, the WD
repeat protein GhWD40 and the unknown protein GhJI1. Among these transcription
factors, previous studies showed that down-regulation of GhMYB25-likeleads
to a fiberless phenotype in cotton seeds. Molecular and genetic evidence showed
that the GhJAZ2 protein suppresses fiber initiation in the overexpressing lines
by interacting with GhMYB25-like and suppressing GhMYB25-like activity. Our
results suggested that GhJAZ2 functions as a primary transcription repressor
during lint and fuzz fiber initiation by interacting with GhMYB25-like, GhGL1,
GhMYC2, GhWD40 and GhJI1 to regulate the JA signalling pathway.
DOI: 10.1111/tpj.13273 IF=5.9