Isolation and Characterization of an Atypical LEA Protein Coding cDNA and its Promoter from Drought-Tolerant Plant Prosopis juliflora Suja George & B. Usha & Ajay Parida Received: 14 February 2008 / Accepted: 9 October 2008 / Published online: 12 November 2008 # Government of India 2008 Abstract Plant growth and productivity are adversely affected by various abiotic and biotic stress factors. Despite the wealth of information on abiotic stress and stress tolerance in plants, many aspects still remain unclear. Prosopis juliflora is a hardy plant reported to be tolerant to drought, salinity, extremes of soil pH, and heavy metal stress. In this paper, we report the isolation and characterization of the complementary DNA clone for an atypical late embryogenesis abundant (LEA) protein (Pj LEA3) and its putative promoter sequence from P. juliflora. Unlike typical LEA proteins, rich in glycine, Pj LEA3 has alanine as the most abundant amino acid followed by serine and shows an average negative hydropathy. Pj LEA3 is significantly different from other LEA proteins in the NCBI database and shows high similarity to indole-3 acetic-acid-induced protein ARG2 from Vigna radiata. Northern analysis for Pj LEA3 in P. juliflora leaves under 90 mM H 2 O 2 stress revealed up-regulation of transcript at 24 and 48 h. A 1.5-kb fragment upstream the 5′ UTR of this gene (putative promoter) was isolated and analyzed in silico. The possible reasons for changes in gene expression during stress in relation to the host plant’ s stress tolerance mechanisms are discussed. Keywords Prosopis juliflora . Abiotic stress . Atypical LEA proteins . Promoter . Phylogenetic analysis Introduction Plant growth and productivity are adversely affected by various abiotic and biotic stress factors. Abiotic stress is the principal cause of crop failure worldwide, causing a dip in average yields for most major crops by more than 50% [1, 2]. The development of crop plants able to grow in these adverse conditions assumes importance in this emerging global context. Despite the wealth of information on abiotic stress and stress tolerance in plants, many aspects still remain unclear. One of the effective ways of analyzing a stress response Appl Biochem Biotechnol (2009) 157:244–253 DOI 10.1007/s12010-008-8398-6 S. George : B. Usha : A. Parida (*) M.S. Swaminathan Research Foundation, Taramani, Chennai 600113, India e-mail: ajay@mssrf.res.in