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The R2R3‐MYB transcription factor HAG1/MYB28 is a regulator of methionine‐derived glucosinolate biosynthesis in Arabidopsis thaliana
Author(s) -
Gigolashvili Tamara,
Yatusevich Ruslan,
Berger Bettina,
Müller Caroline,
Flügge UlfIngo
Publication year - 2007
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03133.x
Subject(s) - glucosinolate , biology , transcription factor , myb , arabidopsis thaliana , plant defense against herbivory , regulator , arabidopsis , mutant , biochemistry , myrosinase , secondary metabolism , methionine , gene , biosynthesis , botany , amino acid , brassica
Summary Methionine‐derived glucosinolates belong to a class of plant secondary metabolites that serve as chemoprotective compounds in plant biotic defense reactions and also exhibit strong anticancerogenic properties beneficial to human health. In a screen for the trans ‐activation potential of various transcription factors toward glucosinolate biosynthetic genes, we could identify the HAG1 ( HIGH ALIPHATIC GLUCOSINOLATE 1 , also referred to as MYB28 ) gene as a positive regulator of aliphatic methionine‐derived glucosinolates. The content of aliphatic glucosinolates as well as transcript levels of aliphatic glucosinolate biosynthetic genes were elevated in gain‐of‐function mutants and decreased in HAG1 RNAi knock‐down mutants. Pro HAG1 : GUS expression analysis revealed strong HAG1 promoter activity in generative organs and mature leaves of A. thaliana plants, the main sites of accumulation of aliphatic glucosinolates. Mechanical stimuli such as touch or wounding transiently induced HAG1/MYB28 expression in inflorescences of flowering plants, and HAG1/MYB28 over‐expression reduced insect performance as revealed by weight gain assays with the generalist lepidopteran herbivore Spodoptera exigua . Expression of HAG1/MYB28 was significantly induced by glucose, indicating a novel transcriptional regulatory mechanism for the integration of carbohydrate availability upon biotic challenge. We hypothesize that HAG1/MYB28 is a novel regulator of aliphatic glucosinolate biosynthesis that controls the response to biotic challenges.