Transcriptional responses to drought stress in root and leaf of chickpea seedling.

Chickpea (Cicer arietinum L.) is an important pulse crop grown mainly in the arid and semi-arid regions of the world. Due to its taxonomic proximity with the model legume Medicago truncatula and its ability to grow in arid soil, chickpea has its unique advantage to understand how plant responds to drought stress. In this study, an oligonucleotide microarray was used for analyzing the transcriptomic profiles of unigenes in leaf and root of chickpea seedling under drought stress, respectively. Microarray data showed that 4,815 differentially expressed unigenes were either ≥ 2-fold up- or ≤ 0.5-fold down-regulated in at least one of the five time points during drought stress. 2,623 and 3,969 unigenes were time-dependent differentially expressed in root and leaf, respectively. 110 pathways in two tissues were found to respond to drought stress. Compared to control, 88 and 52 unigenes were expressed only in drought-stressed root and leaf, respectively, while nine unigenes were expressed in both the tissues. 1,922 function-unknown unigenes were found to be remarkably regulated by drought stress. The expression profiles of these time-dependent differentially expressed unigenes were useful in furthering our knowledge of molecular mechanism of plant in response to drought stress.