Abstract
Wild watermelon is a C3-type xerophyte which inhabit in the Kalahari Desert, Africa. To understand the molecular mechanism for drought tolerance of this plant, an expressed sequence tag (EST) approach was used to analyze changes in gene expression in wild watermelon. Three cDNA libraries were constructed from unstressed, 1- and 3-days drought-stressed leaf tissues, respectively, and a total of 4,859 ESTs were generated by sequencing the 5' ends of randomly-selected cDNA clones. The ESTs were assembled to 2,934 unique consensus sequences, 60% of which had identifiable homologs in the Arabidopsis genome. Comparison of the EST abundance among libraries revealed the massive change in gene expression of the leaves under drought. The sequence of the most abundant EST from the stressed libraries showed significant homology with those of type-3 metallothionein-like proteins from other plants. Northern blot analysis confirmed the expression of this gene is strongly induced in the leaves under drought.
