Phytochrome chromophore deficiency leads to overproduction of jasmonic acid and elevated expression of jasmonate-responsive genes in Arabidopsis.
An Arabidopsis mutant line named hy1-101 was isolated because it shows stunted root growth on medium containing low concentrations of jasmonic acid (JA). Subsequent investigation indicated that even in the absence of JA, hy1-101 plants exhibit shorter roots and express higher levels of a group of JA-inducible defense genes. Here, we show that the hy1-101 mutant has increased production of JA and its jasmonate-related phenotype is suppressed by the coi1-1 mutation that interrupts JA signaling. Gene cloning and genetic complementation analyses revealed that the hy1-101 mutant contains a mutation in the HY1 gene, which encodes a heme oxygenase essential for phytochrome chromophore biosynthesis. These results support a hypothesis that phytochrome chromophore deficiency leads to overproduction of JA and activates COI1-dependent JA responses. Indeed, we show that, like hy1-101, independent alleles of the phytochrome chromophore-deficient mutants, including hy1-100 and hy2 (CS68), also show elevated JA levels and constant expression of JA-inducible defense genes. We further provide evidence showing that, on the other hand, JA inhibits the expression of a group of light-inducible and photosynthesis-related genes. Together, these data imply that the JA-signaled defense pathway and phytochrome chromophore-mediated light signaling might have antagonistic effects on each other.
Zhai
Qingzhe
Q
State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, PR China.
Li
Chang-Bao
CB
Zheng
Wenguang
W
Wu
Xiaoyan
X
Zhao
Jiuhai
J
Zhou
Guoxin
G
Jiang
Hongling
H
Sun
Jiaqiang
J
Lou
Yonggen
Y
Li
Chuanyou
C
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D008027:Light; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism*; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development
D003517:Cyclopentanes; D054883:Oxylipins; D010834:Phytochrome; C011006:jasmonic acid; D010088:Oxidoreductases; D006419:Heme Oxygenase (Decyclizing); C518487:HY2 protein, Arabidopsis