Identification of Differentially Expressed Gene Profiles in Young Roots of Tea [Camellia sinensis (L.) O. Kuntze] Subjected to Drought Stress Using Suppression Subtractive Hybridization

Abstract

Drought is an important abiotic stress that limits the production of tea in different regions of the world. Young roots of tea are responsible for nutrient and water uptake; hence, they are the first tissues to perceive drought stress. In this study, a forward suppression subtractive hybridization library was constructed from the tender roots of drought-tolerant tea (Camellia sinensis (L.) O. Kuntze) cultivar (TV-23) subjected to 21 days of drought stress. A total of 572 quality expressed sequence tags were generated by sequencing of 1,052 random clones which have resulted to 246 unigenes comprising 54 contigs and 192 singlets. The unigenes were assigned to various functional categories, i.e. cellular components, biological processes and molecular functions as defined for the Arabidopsis proteome. There were 13.04% of differentially regulated genes that have been associated to various stresses. A total of 123 putative drought-responsive genes were identified which include candidate genes of ubiquitin-proteasome, glutathione metabolism and sugar metabolism pathways and several transcription factors. In order to determine the possible expression, 10 genes associated to drought-responsive pathways were further analysed by reverse transcription polymerase chain reaction. This study provides a basis for studying the drought tolerance mechanism of this important commercial crop which will also be a valuable resource for the functional genomics study of woody plants in future.