Drought Responsive Genes In Tea Cultivars Grown In Kenya.

ABSTRACT

Tea is one of the most popular non-alcoholic beverages worlwide, and a leading foreign exchange earner and source of livelihood to over three million people in Kenya. However, tea growing areas in Kenya experience abiotic stresses with drought been the most predominant. Tea plants tolerate drought through poorly understood physiological, cellular/biochemical and molecular processes. Development of tea cultivars adapted to water-deficit stress greatly relies on an understanding of mechanisms of plant responses. Use of sequencing technologies provide a fast, cost effective, and reliable approach to generate large expression datasets for functional genomic analysis in plants exposed to drought. In the present study, 18-months old seedling tea from eight cultivars, tolerant and susceptible to drought, were subjected to three levels of treatment consisting of high (34%), moderate (26%) and low (18%) soil moisture content in a rain-out shelter. The experiment was designed in a complete randomized block design with three replications. After three months of exposure to treatment, physiological parameters (leaf water status, shoot growth and gas exchange parameters), biochemical parameters (proline and glycinebetaine levels) were determined. The data generated were subjected to two-way anova using Genstat. For molecular analysis, total RNA extracted was from tolerant and susceptible cultivars under stressed and unstressed conditions. The extracts were used to isolate mRNA which was reverse transcribed to complementary DNA. The sequences/reads generated from the cDNA libraries using 454 GLX sequencer were analysed in silico using bioinformatics tool. There was a reduction in shoot growth, leaf relative water content, shoot water potential and gas exchange parameters that varied significantly, P