Impaired induction of the Jasmonate Pathway in the rice mutant hebiba

The elongation of rice (Oryza sativa) coleoptiles is inhibited
by light, and this photoinhibition was used to screen for
mutants with impaired light response. In one of the isolated
mutants, hebiba, coleoptile elongation was stimulated in the
presence of red light, but inhibited in the dark. Light
responses of endogenous indolyl-3-acetic acid and abscisic acid
were identical between the wild type and the mutant. In
contrast, the wild type showed a dramatic increase of jasmonate
heralded by corresponding increases in the content of its
precursor o-phytodienoic acid, whereas both compounds were not
detectable in the mutant. The jasmonate response to wounding was
also blocked in the mutant. The mutant phenotype was rescued by
addition of exogenous methyl jasmonate and o-phytodienoic acid.
Moreover, the expression of O. sativa 12-oxophytodienoic acid
reductase, an early gene of jasmonic acid-synthesis, is induced
by red light in the wild type, but not in the mutant. This
evidence suggests a novel role for jasmonates in the light
response of growth, and we discuss a cross-talk between
jasmonate and auxin signaling. In addition, hebiba represents
... mehr
the first rice mutant in which the induction of the jasmonate
pathway is impaired providing a valuable tool to study the role
of jasmonates in Graminean development.