ISSN 1021-4437, Russian Journal of Plant Physiology, 2010, Vol. 57, No. 2, pp. 247–252. © Pleiades Publishing, Ltd., 2010. Published in Russian in Fiziologiya Rastenii, 2010, Vol. 57, No.2, pp. 260–265. 247 1 INTRODUCTION In the recent past, cloning, isolation, and identifi- cation of genes/proteins have made a significant con- tribution in plant molecular biology and culminated in the production of a range of transgenic plants with var- ied traits. Genetically engineered biotic/abiotic stress- tolerant plants using already cloned and characterized genes have attracted a great deal of attention in recent years [1–4]. In this respect, the availability of stress- related cDNA clones is a determining and accelerat- ing factor. A large number of plant proteins/genes responding to various biotic stress stimuli, such as bacteria, fungi, and viruses [4, 5] and abiotic stresses stimuli, such as drought, salt, anoxia, and cold have been character- ized [5–8]. To date, drought stress-related genes with various functions have been identified in plants by molecular and genomic analysis. The products of drought stress- related genes have been classified into the two groups including functional and regulatory proteins [9, 10]. The first group includes such molecules as chaper- ones, late embryogenesis abundant (LEA) proteins, osmotin, antifreeze proteins, mRNA-binding pro- teins, key enzymes for osmolyte biosynthesis, water channel proteins, sugar and proline transporters, detoxification enzymes, and various proteases func- 1 This text was submitted by the authors in English. tioning in stress tolerance. The second group is com- prised of regulatory proteins, i.e., protein factors involved in the further regulation of signal transduc- tion and stress-responsive gene expression. These include various transcription factors, protein kinases, protein phosphatases, enzymes involved in phospho- lipid metabolism, and other signaling molecules, such as a calmodulin-binding protein [10, 11]. Signifi- cantly, the introduction of many of these drought stress-inducible genes by gene transfer methods resulted in improved plant stress tolerance [12–15]. Gene expression profiles of plants exposed to abiotic stresses, such as drought, have been recently analyzed by the microarray technology in arabidopsis and rice plants [16–21]. Despite these discoveries, there is a constant need for identification, isolation, and characterization of the increasing number of genes/proteins as well as for identification of the functions of those stress proteins, which have not been assigned for physiological roles thus far. Identification of the precise physiological roles of the most stress genes/proteins has proven a challenging task. However, work employing stress- induced/activated proteins with known functions as well as those with relatively unknown functions has made a major contribution in planning strategies for improving stress tolerance through transgenic tech- nology [1, 2]. RESEARCH PAPERS Identification of DUF538 cDNA Clone from Celosia cristata Expressed Sequences of Nonstressed and Stressed Leaves 1 A. Gholizadeh a and B. Baghban Kohnehrouz b a Research Institute for Fundamental Sciences, University of Tabriz, Tabriz, Iran; fax: 98 (411) 336-3137; e-mail: aghz_bioch@yahoo.co.in b Department of Plant Breeding and Biotechnology, University of Tabriz, Tabriz, Iran Received October 21, 2008 Abstract—DUF538 domain-containing protein family consists of several plant proteins of unknown func- tions. This protein family has already been discovered by genome annotation tools and cloned as an inducible gene product under various environmental stress conditions. For the first time, we presented a full length DUF538 cDNA (encoding 170 amino acid residues) clone, which was randomly isolated from Celosia cristata leaf cDNA library constructed under normal growth conditions and consistently amplified from leaf cDNA populations prepared from nonstressed and drought-stressed leaves. We predicted that a DUF538 gene prod- uct can be a putative candidate for common stress-related protein (regulatory factor) in the plant system. The nucleotide and deduced amino acid sequences of the isolated clone have been submitted to EMBL data bases under accession no. AJ535713. Key words: Celosia cristata - DUF538 gene - expression - stress - cDNA cloning DOI: 10.1134/S1021443710020123