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A Selaginella moellendorffii ortholog of KARRIKIN INSENSITIVE2 functions in Arabidopsis development but cannot mediate responses to karrikins or strigolactones

Citation

Waters, MT and Scaffidi, A and Moulin, SLY and Sun, YK and Flematti, GR and Smith, SM, A Selaginella moellendorffii ortholog of KARRIKIN INSENSITIVE2 functions in Arabidopsis development but cannot mediate responses to karrikins or strigolactones, Plant Cell, 27, (7) pp. 1925-1944. ISSN 1040-4651 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 American Society of Plant Biologists

DOI: doi:10.1105/tpc.15.00146

Abstract

In Arabidopsis thaliana, the α/β-fold hydrolase KARRIKIN INSENSITIVE2 (KAI2) is essential for normal seed germination, seedling development, and leaf morphogenesis, as well as for responses to karrikins. KAI2 is a paralog of DWARF14 (D14), the proposed strigolactone receptor, but the evolutionary timing of functional divergence between the KAI2 and D14 clades has not been established. By swapping gene promoters, we show that Arabidopsis KAI2 and D14 proteins are functionally distinct. We show that the catalytic serine of KAI2 is essential for function in plants and for biochemical activity in vitro. We identified two KAI2 homologs from Selaginella moellendorffii and two from Marchantia polymorpha. One from each species could hydrolyze the strigolactone analog GR24 in vitro, but when tested for their ability to complement Arabidopsis d14 and kai2 mutants, neither of these homologs was effective. However, the second KAI2 homolog from S. moellendorffii was able to complement the seedling and leaf development phenotypes of Arabidopsis kai2. This homolog could not transduce signals from exogenous karrikins, strigolactone analogs, or carlactone, but its activity did depend on the conserved catalytic serine. We conclude that KAI2, and most likely the endogenous signal to which it responds, has been conserved since the divergence of lycophytes and angiosperm lineages, despite their major developmental and morphogenic differences.

Item Details

Item Type:Refereed Article
Keywords:KAI2, Selaginella moellendorffii, Arabidopsis thaliana, karrikins, strigolactone, karrikinolide
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Plant Physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Biological Sciences
Author:Smith, SM (Professor Steven Smith)
ID Code:105515
Year Published:2015
Funding Support:Australian Research Council (DP140104567)
Web of Science® Times Cited:21
Deposited By:Plant Science
Deposited On:2016-01-06
Last Modified:2016-08-11
Downloads:0

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