Identification of drought-induced genes from the leaves of Rangpur lime (Citrus limon (L) Osbeck)

Abstract

Water stress is one of the limiting factors for citrus production and Citrus species show great variation in their response to drought stress. Although the majority of Citrus rootstocks are sensitive to water stress, Rangpur lime (Citrus limon (L) Osbeck) (RL) shows a high degree of drought tolerance. Therefore, it has been used as a rootstock in drought-prone environments, but mechanisms of drought tolerance are not yet known. in this study, to explore the mechanisms of drought adaptation and tolerance, a subtractive cDNA library was constructed from the leaves of 14-day drought-stressed and non-stressed RL for identification of drought-induced genes. 285 cDNA sequences were obtained from randomly selected clones from the subtracted library containing the drought-induced genes. the expression analyses of 200 cDNAs in 14-day drought treated and untreated RL by macroarray hybridisation revealed that the expression of 56 cDNAs increased two to 11-fold. 30 non-redundant drought-induced genes were identified from these cDNAs and drought induction of eight selected genes was confirmed by a real-time RT-PCR assay suggesting that expressions of these genes were regulated by drought-stress. Genes identified in this study were mostly related with cell rescue and defense pathways involved in drought adaptation and tolerance of RL.