The control of seed germination in response to environmental conditions is important for plant success. We investigated the role of the karrikin receptor KARRIKIN INSENSITIVE2 (KAI2) 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 KAI2 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 DLK2 and KUF1 genes and inhibited hypocotyl elongation independently of osmotic stress. Under mild osmotic stress, karrikin enhanced expression of DREB2A, WRKY33 and ERF5 genes, but not ABA signalling genes. Thus, the karrikin-KAI2 signalling system can protect against abiotic stress, first by providing stress tolerance, and second by inhibiting germination under conditions unfavourable to seedling establishment.

Item Type:	Refereed Article
Keywords:	Arabidopsis thaliana, dormanc, karrikin, osmotic stress, seed germination thermoinhibition
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant biochemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the biological sciences
UTAS Author:	Wang, Lu (Dr Lu Wang)
UTAS Author:	Smith, SM (Professor Steven Smith)
ID Code:	152909
Year Published:	2018
Web of Science® Times Cited:	47
Deposited By:	Medicine
Deposited On:	2022-08-26
Last Modified:	2022-09-07
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