Use of Arabidopsis thaliana and its close relative Thellungiella halophila to reveal abiotic stress determinants
Abstract
Salt cress (Thellungiella halophila), a halophyte, is a close relative of Arabidopsis that can be used as molecular genetic model in salt tolerance studies. It has many desirable characteristics to be a model plant such as such as small genome size, short life cycle, high seed yield and efficient transformation. Salt cress is an extremophile native to harsh environments and can reproduce after exposure to extreme salinity (500 mM NaCl) or cold to -15°C. It is a typical halophyte that accumulates NaCl at controlled rates and also dramatic levels of proline (>150 mM) during exposure to high salinity. Stomata of salt cress are distributed on the leaf surface at higher density but are less open than the stomata of Arabidopsis and respond to salt stress by closing more tightly. In this research we present a detailed physiological characterization of this model plant focusing on its applicability to molecular genetic analyses of growth and development of extremophiles. Moreover we report the identification of two Arabidopsis T-DNA tagged mutants. The shs1-1 (sodium hyper sensitive) mutant was generated as second site mutation in the sos3-1 background and isolated as sos3 enhancer. The shs1 mutation has pleiotropic effects on seedling development such as altered leaf mophology, sucrose hypersensitivity and ABA insensitivity. SHS1 encodes a putative adenylate translocator-like protein and subcellular localization of SHS1 indicates endoplasmic reticulum. The second mutant isolated is hos6-1 (for high expression of osmotically responsive genes) in which expression of RD29A::LUC was hyperactivated by ABA, salinity stress and low temperature. hos6-1 plants displayed a significant increase in tolerance to soil dehydration. The basta resistance of hos6-1 cosegregates with the ABA hypersensitive phenotypes indicating that the responsible mutation results from an insertion of the T-DNA carrying the BAR gene. HOS6 appears to play an important role in ABA signaling and response to dehydration stress.
Degree
Ph.D.
Advisors
Bressan, Purdue University.
Subject Area
Botany|Plant pathology
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