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Karrikin‐KAI2 signalling provides Arabidopsis seeds with tolerance to abiotic stress and inhibits germination under conditions unfavourable to seedling establishment
Author(s) -
Wang Lu,
Waters Mark T.,
Smith Steven M.
Publication year - 2018
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.15192
Subject(s) - germination , hypocotyl , abiotic stress , arabidopsis , seedling , osmotic shock , strigolactone , biology , mutant , osmolyte , botany , abiotic component , gibberellin , elongation , wild type , horticulture , gene , biochemistry , ecology , materials science , ultimate tensile strength , metallurgy
Summary The control of seed germination in response to environmental conditions is important for plant success. We investigated the role of the karrikin receptor KARRIKIN INSENSITIVE 2 ( KAI 2) in the response of Arabidopsis seeds to osmotic stress, salinity and high temperature. Germination of the kai2 mutant was examined in response to NaCl, mannitol and elevated temperature. The effect of karrikin on germination of wild‐type seeds, hypocotyl elongation and the expression of karrikin‐responsive genes was also examined in response to such stresses. The kai2 seeds germinated less readily than wild‐type seeds and germination was more sensitive to inhibition by abiotic stress. Karrikin‐induced KAI 2 signalling stimulated germination of wild‐type seeds under favourable conditions, but, surprisingly, inhibited germination in the presence of osmolytes or at elevated temperature. By contrast, GA stimulated germination of wild‐type seeds and mutants under all conditions. Karrikin induced expression of DLK 2 and KUF 1 genes and inhibited hypocotyl elongation independently of osmotic stress. Under mild osmotic stress, karrikin enhanced expression of DREB 2A , WRKY 33 and ERF 5 genes, but not ABA signalling genes. Thus, the karrikin‐ KAI 2 signalling system can protect against abiotic stress, first by providing stress tolerance, and second by inhibiting germination under conditions unfavourable to seedling establishment.