Functional characterization of abiotic stress mutants in Arabidopsis thaliana using a molecular genetic and physiological approach
Abstract
The potential consequences of abiotic stresses are drastic in terms of overall yield potential of different crop species. The need for deciphering the mechanism by which plants sense, transduce and respond to these stresses is crucial to increasing agricultural productivity and sustainability. I present results of the characterization of two mutants isolated using a forward genetics approach by two different screening methods. hos3 was isolated using a reporter gene-based strategy to screen for mutants affected in abiotic stress-regulated gene transcription by visualizing RD29A:LUC luminescence in response to NaCl and ABA. HOS3 encodes an ELO-like gene involved in the synthesis of very long chain fatty acids (VLCFAs) and regulates ABA-mediated signal transduction under control and stress conditions. HOS3 attenuates root response to NaCl and ABA as well as stomatal response to ABA while promoting stomatal opening under control conditions and release of seed dormancy. Specifically, these results suggest novel regulation of abiotic stress signaling by VLCFAs and implicate sphingolipids as effectors of abiotic stress responses in plants. nsr is an untagged mutant isolated by screening for enhanced NaCl-sensitive root growth that displays a novel subset of phenotypes not seen in previously characterized ABA signaling mutants. Stomatal density, water loss rate, stomatal aperture and ABA inhibition of germination in nsr are identical to wildtype responses. In contrast, while nsr waterloss and stomatal aperture in response to ABA-treatment is characteristic of an ABA-insensitive mutant, this mutant's enhanced germination on NaCl, but not ABA, is typical of an ABA-biosynthesis mutant. Further, nsr root growth is more sensitive to osmotic stress both in vitro and in vivo, but has normal inhibition of root growth with ABA treatment. These results contribute to understanding the complexity of ABA-signaling in osmotic-stress adaptation and offer insights regarding the function of these genes in controlling germination, water loss and root growth during osmotic stress that could be potentially exploited for crop improvement.
Degree
Ph.D.
Advisors
Joly, Purdue University.
Subject Area
Molecular biology|Botany|Genetics
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