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An ethylene‐hypersensitive methionine sulfoxide reductase regulated by NAC transcription factors increases methionine pool size and ethylene production during kiwifruit ripening
Author(s) -
Fu Beiling,
Wang Wenqiu,
Liu Xiaofen,
Duan Xuewu,
Allan Andrew C.,
Grierson Donald,
Yin Xueren
Publication year - 2021
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.17560
Subject(s) - ethylene , ripening , methionine , methionine sulfoxide reductase , biochemistry , chemistry , transcription factor , gene expression , biology , gene , amino acid , food science , catalysis
Summary Ethylene plays an important role in regulating fruit ripening by triggering dynamic changes in expression of ripening‐associated genes, but the functions of many of these genes are still unknown. Here, a methionine sulfoxide reductase gene ( AdMsrB1 ) was identified by transcriptomics‐based analysis as the gene most responsive to ethylene treatment in ripening kiwifruit. The AdMsrB1 protein exhibits a stereospecific activity toward the oxidative stress‐induced R enantiomer of methionine sulfoxide (MetSO), reducing it to methionine (Met). Stable overexpression of AdMsrB1 in kiwifruit significantly increased the content of free Met and 1‐aminocyclopropane‐1‐carboxylic acid (ACC), the immediate precursor of ethylene, and increased ethylene production. Dual‐luciferase assays indicated that the AdMsrB1 promoter was not directly upregulated by ethylene treatment but was modulated by two ethylene‐inducible NAM/ATAF/CUC transcription factors ( AdNAC2 and AdNAC72 ) that bind directly to the AdMsrB1 promoter. Overexpression of AdNAC72 in kiwifruit not only enhanced AdMsrB1 expression, but also increased free Met and ACC content and ethylene production rates. This finding establishes an unexpected regulatory loop that enhances ethylene production and the concentration of its biosynthetic intermediates.