Global gene expression pattern in a forest tree species, Tectona grandis (Linn. F.), under limited water supply

Global climate change phenomena have led to drought-like situation in many parts of the world. This has major impact on forest growth and development. Among forest tree species, Tectona grandis, commonly known as Teak, is one of the important forest tree species. Limited water availability during early stage of Teak sapling establishment leads to failure in various reforestation programs. Here, we report how global gene expression is affected in Teak sapling during limited water availability (DT) against well watered (DC). The RNA sequencing of combined libraries of DT and DC retrieved 142,539 contigs, assembled in to 110,374 unigenes. Overall, 63,265 unigenes (57%) were annotated against different data bases. Analysis of the most significant gene ontology terms indicated metabolic process, transport process, and response to stress were the important pathways affected during limited water supply. Among the primary metabolic processes, carbohydrate metabolisms related genes were significantly upregulated in DT followed by protein and lipid metabolisms. On the other hand, the major unigenes of secondary metabolic processes upregulated in DT were laccase/diphenol oxidase family protein (8.7-fold), cytochrome P450 family (8.0-fold), and S-adenosyl methionine synthetase family protein (7.4-fold). Further, a total of 34,707 potential simple sequence repeats (SSRs) and 4215 primers were identified from T. grandis transcripts. The differentially expressed transcripts identified in our study provide primary information about key genes in stress response and performing functional analysis to reveal their roles in stress adaptation in plants, especially in forest tree species.