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High levels of jasmonic acid antagonize the biosynthesis of gibberellins and inhibit the growth of N icotiana attenuata stems
Author(s) -
Heinrich Maria,
Hettenhausen Christian,
Lange Theo,
Wünsche Hendrik,
Fang Jingjing,
Baldwin Ian T.,
Wu Jianqiang
Publication year - 2013
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/tpj.12058
Subject(s) - jasmonic acid , gibberellin , biology , biosynthesis , abscisic acid , secondary metabolism , botany , mutant , arabidopsis , microbiology and biotechnology , gene , biochemistry
Summary Hormones play pivotal roles in regulating plant development, growth, and stress responses, and cross‐talk among different hormones fine‐tunes various aspects of plant physiology. Jasmonic acid ( JA ) is important for plant defense against herbivores and necrotic fungi and also regulates flower development; in addition, A rabidopsis mutants over‐producing JA usually have stunted stems and wound‐induced jasmonates suppress A rabidopsis growth, suggesting that JA is also involved in stem elongation. Gibberellins ( GA s) promote stem and leaf growth and modulate seed germination, flowering time, and the development of flowers, fruits, and seeds. However, little is known about the interaction between the JA and GA pathways. Two calcium‐dependent protein kinases, CDPK 4 and CDPK 5, are important suppressors of JA accumulation in a wild tobacco species, N icotiana attenuata . The stems of N . attenuata silenced in CDPK4 and CDPK5 (ir CDPK 4/5 plants) had dramatically increased levels of JA and exhibited stunted elongation and had very high contents of secondary metabolites. Genetic analysis indicated that the high JA levels in ir CDPK 4/5 stems accounted for the suppressed stem elongation and the accumulation of secondary metabolites. Supplementation of GA 3 to ir CDPK 4/5 plants largely restored normal stem growth to wild‐type levels. Measures of GA levels indicated that over‐accumulation of JA in ir CDPK 4/5 stems inhibited the biosynthesis of GA s. Finally, we show that JA antagonizes GA biosynthesis by strongly inhibiting the transcript accumulation of GA20ox and possibly GA13ox , the key genes in GA production, demonstrating that high JA levels antagonize GA biosynthesis in stems.