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The B‐box protein BBX19 suppresses seed germination via induction of ABI5
Author(s) -
Bai Mengjuan,
Sun Jingjing,
Liu Jinyi,
Ren Haoran,
Wang Kang,
Wang Yanling,
Wang Changquan,
Dehesh Katayoon
Publication year - 2019
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.14415
Subject(s) - photomorphogenesis , abscisic acid , repressor , germination , inducer , microbiology and biotechnology , biology , psychological repression , rna interference , hypocotyl , regulator , botany , transcription factor , gene , arabidopsis , genetics , gene expression , rna , mutant
Summary Seed germination is a fundamental process in the plant life cycle and is regulated by functionally opposing internal and external inputs. Here we explored the role of a negative regulator of photomorphogenesis, a B‐box‐containing protein (BBX19), as a molecular link between the inhibitory action of the phytohormone abscisic acid (ABA) and the promoting role of light in germination. We show that seeds of BBX19 ‐overexpressing lines, in contrast to those of BBX19 RNA interference lines, display ABA hypersensitivity, albeit independently of elongated hypocotyl 5 (HY5). Moreover, we establish that BBX19 functions neither via perturbation of GA signaling, the ABA antagonistic phytohormone, nor through interference with the DELLA protein germination repressors. Rather, BBX19 functions as an inducer of ABA INSENSITIVE5 ( ABI5 ) by binding to the light‐responsive GT1 motifs in the gene promoter. In summary, we identify BBX19 as a regulatory checkpoint, directing diverse developmental processes and tailoring adaptive responses to distinct endogenous and exogenous signals.