Isolation of cDNAs differentially expressed in response to drought stress and characterization of the Ca-LEAL1 gene encoding a new family of atypical LEA-like protein homologue in hot pepper (Capsicum annuum L. cv. Pukang)  Jong-A. Park a , Seok Keun Cho a , Jee Eun Kim a , Hoo Sun Chung a , Jong-Pil Hong a , Baik Hwang b , Choo Bong Hong c , Woo Taek Kim a, * a Department of Biology, College of Science, Yonsei University, Seoul 120-749, South Korea b Department of Biology, Chonnam National University, Kwangju 500-757, South Korea c School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, South Korea Received 8 March 2003; received in revised form 1 April 2003; accepted 3 April 2003 Abstract Among various abiotic stresses, water deficit is one of the most severe environmental factors responsible for the reduction of crop yield in many parts of the world. By means of the mRNA differential display technique, seven cDNAs (pCa-DIs for Capsicum annuum drought induced) have been isolated that are rapidly induced when hot pepper plants are subjected to water stress (5  /20% loss of fresh weight). For all of the isolated Ca-DIs , database search provided significant sequence similarity to previously described genes from different plant species. The predicted proteins encoded by the Ca-DI genes are putatively involved in processes as diverse as primary metabolism, protein degradation, cell wall modification and stress response, suggesting the complexity of cellular responses to drought stress in hot pepper plants. Particularly, we analyzed the detailed structural property and expression pattern of the Ca-DI4 (Ca-LEAL1 ) gene. Sequence homology studies indicate that Ca-LEAL1 (M r /19.3 kDa) belongs to a new family of atypical hydrophobic late embryogenesis-abundant-like (LEA-like) proteins. Expression analysis showed that Ca-LEAL1 was strongly activated by drought and salt stresses, and also in response to mechanical wounding in both local and systemic leaves. Moreover, the level of Ca-LEAL1 transcript was rapidly enhanced by exogenous application of ABA and ethylene. These results are consistent with the notion that an atypical hydrophobic Ca-LEAL1 protein is subject to control by diverse environmental factors and that ethylene, in conjunction with ABA, plays an important role in the regulation of the stress gene in hot pepper plants. The possible physiological functions of Ca-LEAL1 as well as other Ca-DI proteins in the adaptive process against drought stress are discussed # 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: ABA; Abiotic stresses; Atypical LEA-like protein; DD-PCR; Ethylene; Hot pepper 1. Introduction Abiotic stresses, including drought, high salinity and extreme temperatures, greatly impair the growth and development of soil plants. Among these abiotic stres- ses, drought or water deficit is the most severe environ- mental factor responsible for the reduction of crop yield in many parts of the world. A number of genetic and cellular events that occur under such stress have been widely documented [1,2]. Although a large and increas- ing number of genes induced by drought stress have been recently identified with the aid of combination of molecular and genetic approaches, their physiological roles in relation to either tolerance or sensitivity are largely unknown in higher plants [3  /6]. Thus, it is  The nucleotide sequence data reported in this paper have been deposited in the GenBank database under the accession number AF543310. * Corresponding author. Tel.:  /82-2-2123-2661; fax:  /82-2-312- 5657. E-mail address: wtkim@yonsei.ac.kr (W.T. Kim). Plant Science 165 (2003) 471  /481 www.elsevier.com/locate/plantsci 0168-9452/03/$ - see front matter # 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0168-9452(03)00165-1