Abstract
An EST sequence, designated
JnRAP2-like, was isolated from tissue at the heartwood/sapwood transition zone (TZ) in black walnut (
Juglans nigra L). The deduced amino acid sequence of JnRAP2-like protein consists of a single AP2- containing domain with significant similarity to conserved AP2/ERF DNA-binding domains in other species. Based on multiple sequence alignment,
JnRAP2-like appears to be an ortholog of
RAP2.6L (At5g13330), which encodes an ethylene response element binding protein in
Arabidopsis thaliana. Real-time PCR revealed that the
JnRAP2-like was expressed most abundantly in TZ of trees harvested in fall when compared with other xylem tissues harvested in the fall or summer. Independent transgenic lines over-expressing
JnRAP2-like in
Arabidopsis developed dramatic ethylene-related phenotypes when treated with 50 μM methyl jasmonate (MeJA). Taken together, these results indicated that
JnRAP2-like may participate in the integration of ethylene and jasmonate signals in the xylem and other tissues. Given the role of ethylene in heartwood formation, it is possible
JnRAP2-like expression in the transition zone is part of the signal transduction pathway leading to heartwood formation in black walnut.
Citation
Huang, Zhonglian; Zhao, Peng; Medina, Jose; Meilan, Richard; Woeste, Keith. 2013. Roles of
JnRAP2.6-like from the transition zone of black walnut in hormone signaling. PLoS ONE. 8(11): e75857. 14 p.
