A pea chloroplast translation elongation factor that is regulated by abiotic factors q,qq B.N. Singh, R.N. Mishra, Pradeep K. Agarwal, Mamta Goswami, Suresh Nair, S.K. Sopory, and M.K. Reddy * International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110 067, India Received 5 May 2004 Available online Abstract We report the cloning and characterization of both the cDNA (tufA) and genomic clones encoding for a chloroplast translation elongation factor (EF-Tu) from pea. The analysis of the deduced amino acids of the cDNA clone reveals the presence of putative transit peptide sequence and four GTP binding domains and two EF-Tu signature motifs in the mature polypeptide region. Using in vivo immunostaining followed by confocal microscopy pea EF-Tu was localized to chloroplast. The steady state transcript level of pea tufA was high in leaves and not detectable in roots. The expression of this gene is stimulated by light. The differential expression of this gene in response to various abiotic stresses showed that it is down-regulated in response to salinity and ABA and up-regulated in response to low temperature and salicylic acid treatment. These results indicate that regulation of pea tufA may have an important role in plant adaptation to environmental stresses. Ó 2004 Elsevier Inc. All rights reserved. Keywords: Confocal microscopy; Immunostaining; Pisum sativum; Plant promoter Plant growth and development are adversely affected by abiotic stress factors due to their sessile growth habit. However, plants respond to environmental stress through altered gene expression and illicit adaptive re- sponses, such as the production of stress adaptive pro- teins, synthesis of oxidative stress protectors, and accumulation of protective solutes [14]. In recent years, using cDNA microarray technology, it has been found that the number of genes that respond to different stresses is very large [16,28]. To understand the molec- ular regulation of these processes, the relevant subsets of differentially expressed genes must be identified and the regulated expression mechanisms of these genes under- stood. Recently Guo et al. [13] showed the involvement of translation elongation factor 2 in Arabidopsis for the low temperature induced cold acclimation. Additionally, Rausell et al. [22] showed that the overexpression of sugar beet translation initiation factor increases salt tolerance in both yeast and Arabidopsis and also improves in vitro protein synthesis under salt stress condition. These stud- ies suggest the importance of protein synthesizing ma- chinery and its role in abiotic stress adaptation in plants. Previously, it was shown in maize that the increased thermal tolerance is associated with 45 kDa heat shock protein [26]. Subsequently, this protein was identified as EF-Tu [3]. EF-Tu has been shown to have chaperone-like property other than its role in polypeptide elongation in bacterial system [7] of refolding the denatured proteins or preventing their aggregations during heat stress. Pro- karyotic and plastid specific EF-Tu proteins are strikingly similar and thus, it is possible that the plastid specific EF- Tu may play a role in stress adaptation. q The nucleotide sequence data reported here appears in the EMBL, GenBank, and DDBJ Nucleotide Sequence Databases under the Accession Nos. Y14561 and AY083613. qq Abbreviations: ABA, abscisic acid; cDNA, complementary DNA; EF-Tu, chloroplast elongation factor; mRNA, messenger RNA; PCR, polymerase chain reaction; tufA, gene coding for chloroplast elongation factor. * Corresponding author. Fax: +91-11-26162316. E-mail address: reddy@icgeb.res.in (M.K. Reddy). 0006-291X/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2004.05.192 Biochemical and Biophysical Research Communications 320 (2004) 523–530 BBRC www.elsevier.com/locate/ybbrc