Comparative transcriptome analysis of salt-tolerant wheat germplasm lines using wheat genome arrays
Introduction
Abiotic stresses such as drought, salinity, and temperature have been shown to reduce average crop yield by more than 50% with yield losses for wheat as great as 80% [1]. It is estimated that 20–30% of the world's irrigated soil is adversely affected by salinity [2], [3]. Salt stress in plants is due primarily to ion cytotoxicity involving alteration of cytosolic K+/Na+ ratios and osmotic stress that disrupts homeostasis and ion distribution in the cell [4], [5] leading to denaturation of structural and functional proteins [6].
Plants survive in saline soils by excluding Na+ at the plasma membrane [4], [7], [8], sequestering Na+ in intracellular vacuoles [9], [10], and accumulation of osmolites and osmoprotectants [11]. The end result of these mechanisms is proper K+/Na+ ratios and correct cellular osmolarity. Varieties of barley and tomato exhibit high variations in salt tolerance [12], which suggests that mutations exist in functional or regulatory genes that can confer salt tolerance on salt-sensitive plants [3]. However, wild annual and perennial wheatgrasses have even greater salt tolerance than cultivated crops [13], [14], [15].
Two salinity-tolerant wheat recombinant lines, W4909 and W4910 [16], were generated by crossing a wheat disomic addition line AJDAj5, which harbors a pair of Thinopyrum junceum Eb chromosomes [17], with the Aegilops speltoides derived Ph inhibitor line PhI [18] that promotes homoeologous recombination. W4909 and W4910 have been estimated to be genetically different from Chinese Spring by 1.9% and 2.4%, respectively, using AFLP markers [16]. Both lines have greater salt tolerance than either parent (AJDAj5 and PhI), which have greater tolerance than the Chinese Spring background [16]. We hypothesize that some genes that are transferred from the AJDAj5 and PhI parents contribute to the enhanced salt tolerance in the recombinant lines. In this study we utilized microarray analysis to assess the gene expression differences in these lines, measure the contribution of AJDAj5 and PhI to each line, and identify expression polymorphisms unique to salt tolerant W4909 and W4910 with respect to the more salt-sensitive Chinese Spring. We report here the results of transcriptome analysis of W4909, W4910, the parental lines AJDAj5 and PhI, and the common background Chinese Spring under salt stress conditions.
Section snippets
Plant materials
Wheat plants representing germplasm lines W4909 and W4910 [16], AJDAj5 [17], PhI [18], and cv. Chinese Spring were grown in a greenhouse under natural light from mid-March through mid-April with diurnal temperature range of 60–85 °F at the USDA-ARS Forage and Range Research Laboratory in Logan, Utah. Plants were grown in 70-grain silica sand with one plant per Cone-tainer1
Identification of expression polymorphisms in salt-stressed W4909 and W4910 wheat germplasm and their parental lines
Wheat germplasm lines W4909 and W4910 are more salt tolerant than either of their parental lines AJDAj5 and PhI [16]. Microarray analysis was used to identify differentially expressed genes in roots and shoots and determine the parental contribution to enhanced salt tolerance in these lines. Significantly different (greater than 2-fold) patterns of transcript expression that were attributable to one or the other parental lines were identified as expression level polymorphisms (ELPs) and are
Acknowledgments
This research is supported by USDA-ARS Administrator's Postdoctoral Research Associate Program, 2003 class.
References (36)
Plant salt tolerance
Trends Plant Sci.
(2001)Plant resistance to environmental stress
Curr. Opin. Biotechnol.
(1998)- et al.
Plant ion channels: from molecular structures to physiological functions
Curr. Opin. Plant Biol.
(1999) Sodium transport and salt tolerance in plants
Curr. Opin. Cell. Biol.
(2000)- et al.
Plant stress adaptations – making metabolism move
Curr. Opin. Plant Biol.
(1998) Evaluation of some recombinant lines of Triticum turgidum L. for salt tolerance
J. Arid Environ.
(2000)- et al.
Evaluation of salt-tolerant genotypes of durum wheat derived from in vitro and field experiments
Field Crops Res.
(2005) - et al.
Expression and promoter analysis of the TaLTP1 gene induced by drought and salt stress in wheat (Triticum aestivum L.)
Plant Sci.
(2004) - et al.
Direct interaction of a divergent CaM isoform and the transcription factor, MYB2, enhances salt tolerance in Arabidopsis
J. Biol. Chem.
(2005) - et al.
Comparative EST profiles of leaf and root of Leymus chinensis, a xerophilous grass adapted to high pH sodic soil
Plant Sci.
(2006)
Receptor kinase activation and signal transduction in plants: an emerging picture
Curr. Opin. Plant Biol.
Plant productivity and environment
Science
Breeding for salinity resistance in crop plants, where next?
Aust. J. Plant Physiol.
Taking transgenic plants with a pinch of salt
Science
A glimpse of the mechanisms of ion homeostasis during salt stress
J. Exp. Bot.
Salt tolerance conferred by overexpression of a vacuolar Na+/H+ antiport in Arabidopsis
Science
The Arabidopsis thaliana proton transporters, AtNhx1 and Avp1, can function in cation detoxification in yeast
Proc. Natl. Acad. Sci. U.S.A.
Saline culture of crops: a genetic approach
Science
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