Flower jasmonates control fertility but largely disconnect from defense metabolites in reproductive tissues of rice (Oryza sativa L.).

Abstract

While sterile phenotypes of Osjar1 and Osaoc (hebiba) mutants corroborate the essential role of jasmonates (JAs) in reproductive development of rice (Oryza sativa L.), it remains unclear how other JA-dependent defense functions operate in reproductive tissues. We show that various JAs, including bioactive JA-Ile, gradually accumulate in the rice spikelets, and peak at anthesis, but majority of JAs remain localized in the stamens. While other spikelet parts contained only a low basal level of JAs, whole flowers responded to mechanical damage by the elicitation of a strong JA burst. Similarly, whole flowers increased their already present basal levels of defense metabolites in response to wounding, namely phenolamides and momilactone diterpenes, but these contents were only partially dependent on JA. Our data suggest that while JAs acquired essential role(s) in rice fertility, floral defense was largely diverted to yet another signaling pathway(s) that complement the canonical JA and/or JA-Ile stress signaling in reproductive parts of rice.