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Putrescine metabolism modulates the biphasic effects of brassinosteroids on canola and Arabidopsis salt tolerance
Author(s) -
Liu Jinlong,
Yang Rongchen,
Jian Ni,
Wei Long,
Ye Liaoliao,
Wang Ruihua,
Gao Huiling,
Zheng Qingsong
Publication year - 2020
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.13757
Subject(s) - canola , arabidopsis , putrescine , crosstalk , metabolism , biosynthesis , mutant , chemistry , agmatine , biochemistry , biology , botany , microbiology and biotechnology , enzyme , gene , physics , optics
Brassinosteroids (BRs) are known to improve salt tolerance of plants, but not in all situations. Here, we show that a certain concentration of 24‐epibrassinolide (EBL), an active BR, can promote the tolerance of canola under high‐salt stress, but the same concentration is disadvantageous under low‐salt stress. We define this phenomenon as hormonal stress‐level‐dependent biphasic (SLDB) effects. The SLDB effects of EBL on salt tolerance in canola are closely related to H 2 O 2 accumulation, which is regulated by polyamine metabolism, especially putrescine (Put) oxidation. The inhibition of EBL on canola under low‐salt stress can be ameliorated by repressing Put biosynthesis or diamine oxidase activity to reduce H 2 O 2 production. Genetic and phenotypic results of bri1‐9 , bak1 , bes1‐D , and bzr1‐1D mutants and overexpression lines of BRI1 and BAK1 in Arabidopsis indicate that a proper enhancement of BR signaling benefits plants in countering salt stress, whereas excessive enhancement is just as harmful as a deficiency. These results highlight the involvement of crosstalk between BR signaling and Put metabolism in H 2 O 2 accumulation, which underlies the dual role of BR in plant salt tolerance.