Cold-Regulated Cereal Chloroplast Late Embryogenesis Abundant-Like Proteins. Molecular Characterization and Functional Analyses

Abstract

Cold acclimation and freezing tolerance are the result of complex interaction between low temperature, light, and photosystem II (PSII) excitation pressure. Previous results have shown that expression of the Wcs19 gene is correlated with PSII excitation pressure measured in vivo as the relative reduction state of PSII. Using cDNA library screening and data mining, we have identified three different groups of proteins, late embryogenesis abundant (LEA) 3-L1, LEA3-L2, and LEA3-L3, sharing identities with WCS19. These groups represent a new class of proteins in cereals related to group 3 LEA proteins. They share important characteristics such as a sorting signal that is predicted to target them to either the chloroplast or mitochondria and a C-terminal sequence that may be involved in oligomerization. The results of subcellular fractionation, immunolocalization by electron microscopy and the analyses of target sequences within the Wcs19 gene are consistent with the localization of WCS19 within the chloroplast stroma of wheat (Triticum aestivum) and rye (Secale cereale). Western analysis showed that the accumulation of chloroplastic LEA3-L2 proteins is correlated with the capacity of different wheat and rye cultivars to develop freezing tolerance. Arabidopsis was transformed with the Wcs19 gene and the transgenic plants showed a significant increase in their freezing tolerance. This increase was only evident in cold-acclimated plants. The putative function of this protein in the enhancement of freezing tolerance is discussed.

Genetic approaches towards overcoming water deficit in plants - special emphasis on LEAs

“…WCS19 (encoding for a wheat LEA3-L2 protein) constitutively expressed in Arabidopsis resulted in significant freezing tolerance and resistance to photoinhibition (Ndong et al, 2002). Under in vitro conditions, an algal (Chlorella vulgaris) LEA 3 protein diminished the freeze-induced damage of the enzyme lactate dehydrogenase (Honjoh et al, 2000).…”

Virus-induced silencing of genes encoding LEA protein in Tibetan hulless barley (Hordeum vulgare ssp. vulgare) and their relationship to drought tolerance

“…Although many researchers have indicated that transgenic plants expressing LEA proteins under the control of regulated or constitutive promoters showed tolerant phenotypes under drought, high salinity or freezing stress (Xu et al 1996;Sivamani et al 2000;NDong et al 2002;Babu et al 2004;Puhakainen et al 2004;Fu et al 2007;Lal et al 2008;Xiao et al 2007;Dalal et al 2009), this ''gain-of-function'' approach may not sufficiently reflect their direct participation in the plant's adjustment or adaptation to these stress conditions but rather their potential to confer tolerance when ectopically expressed (Olvera-Carrillo et al 2010). In recent years, a reverse genetics technology called VIGS has being employed by many researchers (Kumagai et al 1995;Ratcliff et al 1997;Baulcombe 1999;Liu et al 2002).…”

Osmotic stress stimulates shoot organogenesis in callus of rice (Oryza sativa L.) via auxin signaling and carbohydrate metabolism regulation

“…Late embryogenesis abundant (LEA) proteins are an ABA-dependent protein family. The proteins can be detected in embryo and tissue with water stress (NDong et al 2002;Grelet et al 2005;Shih et al 2010). Because OsLEA1 can be detected in rice callus and is an ABA-induced gene (Shih et al 2010), the gene expression could present as the endogenous ABA level.…”