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Linking phytochrome to plant immunity: low red : far‐red ratios increase A rabidopsis susceptibility to B otrytis cinerea by reducing the biosynthesis of indolic glucosinolates and camalexin
Author(s) -
Cargnel Miriam D.,
Demkura Patricia V.,
Ballaré Carlos L.
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13032
Subject(s) - glucosinolate , jasmonate , biosynthesis , arabidopsis , biology , botrytis cinerea , plant defense against herbivory , myrosinase , mutant , biochemistry , arabidopsis thaliana , methyl jasmonate , pistacia , botany , gene , brassica
Summary Shade‐intolerant plants respond to low red : far‐red ( R  :  FR ) ratios, which signal the proximity of potential competitors, by down‐regulating immune responses. Here we investigated the mechanisms underlying this immune suppression in A rabidopsis. We used genetic, transcriptomic and metabolomic approaches to examine the functional connections between R  :  FR ratio and Arabidopsis resistance to the fungus B otrytis cinerea . Low R  :  FR ratios reduced the concentration of indol‐3‐ylmethyl glucosinolate (I3M) (an indolic glucosinolate, iGS ) and camalexin in plants inoculated with B . cinerea , and attenuated the I3M response triggered by jasmonate elicitation. These effects on metabolite abundance correlated with reduced expression of iGS and camalexin biosynthetic genes. Furthermore, the effect of low R  :  FR increasing A rabidopsis susceptibility to B . cinerea was not present in mutants deficient in the biosynthesis of camalexin ( pad3 ) or metabolism of iGS ( pen2 ). Finally, in a mutant deficient in the JASMONATE ZIM DOMAIN ‐10 ( JAZ 10) protein, which does not respond to low R  :  FR with increased susceptibility to B . cinerea , supplemental FR failed to down‐regulate iGS production. These results indicate that suppression of A rabidopsis immunity against B . cinerea by low R  :  FR ratios is mediated by reduced levels of Trp‐derived defenses, and provide further evidence for a functional role of JAZ 10 in the link between phytochrome and jasmonate signaling.

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