Methyl jasmonate reduces grain yield by mediating stress signals to alter spikelet development in rice.
Jasmonic acid (JA) is involved in plant development and the defense response. Transgenic overexpression of the Arabidopsis (Arabidopsis thaliana) jasmonic acid carboxyl methyltransferase gene (AtJMT) linked to the Ubi1 promoter increased levels of methyl jasmonate (MeJA) by 6-fold in young panicles. Grain yield was greatly reduced in Ubi1:AtJMT plants due to a lower numbers of spikelets and lower filling rates than were observed for nontransgenic (NT) controls. Ubi1:AtJMT plants had altered numbers of spikelet organs, including the lemma/palea, lodicule, anther, and pistil. The loss of grain yield and alteration in spikelet organ numbers were reproduced by treating NT plants with exogenous MeJA, indicating that increased levels of MeJA in Ubi1:AtJMT panicles inhibited spikelet development. Interestingly, MeJA levels were increased by 19-fold in young NT panicles upon exposure to drought conditions, resulting in a loss of grain yield that was similar to that observed in Ubi1:AtJMT plants. Levels of abscisic acid (ABA) were increased by 1.9- and 1.4-fold in Ubi1:AtJMT and drought-treated NT panicles, respectively. The ABA increase in Ubi1:AtJMT panicles grown in nondrought conditions suggests that MeJA, rather than drought stress, induces ABA biosynthesis under drought conditions. Using microarray and quantitative polymerase chain reaction analyses, we identified seven genes that were regulated in both Ubi1:AtJMT and drought-treated NT panicles. Two genes, OsJMT1 and OsSDR (for short-chain alcohol dehydrogenase), are involved in MeJA and ABA biosynthesis, respectively, in rice (Oryza sativa). Overall, our results suggest that plants produce MeJA during drought stress, which in turn stimulates the production of ABA, together leading to a loss of grain yield.
Kim
Eun Hye
EH
School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449-728, Korea.
Kim
Youn Shic
YS
Park
Su-Hyun
SH
Koo
Yeon Jong
YJ
Choi
Yang Do
YD
Chung
Yong-Yoon
YY
Lee
In-Jung
IJ
Kim
Ju-Kon
JK
D000040:Abscisic Acid / Q000378:metabolism; D000085:Acetates / Q000378:metabolism* / Q000494:pharmacology; D017360:Arabidopsis / Q000201:enzymology; D018533:Biomass; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D055864:Droughts; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D008780:Methyltransferases / Q000378:metabolism; D012275:Oryza / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D054883:Oxylipins / Q000378:metabolism* / Q000494:pharmacology; D010641:Phenotype; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
D000085:Acetates; D003517:Cyclopentanes; D054883:Oxylipins; D012333:RNA, Messenger; D000040:Abscisic Acid; C072239:methyl jasmonate; D008780:Methyltransferases; C425043:jasmonic acid carboxyl methyltransferase