Drought is the chief constraints limiting Chickpea (Cicer arietinum L.) productivity which makes a considerable difference between its potential and real yield. The main goal of this research was to evaluate the expression of cpdhn1, as a drought resistant candidate gene, under drought stress condition. Four distinct genotypes of chickpea with different levels of drought tolerance were planted in a factorial-split plot experiment with four replications and the drought stress was imposed on the basis of Field Capacity (25%FC) at the flowering stage. Several traits were investigated in three sampling times (pre-stress, stress and recovery stages) and the relative expressions of cpdhn1 were studied in the pre-stress, stress (6hr and 48hr after applying the stress, respectively) and recovery stage using RT-PCR reactions, simultaneously. A rapid and considerable increase in the relative expression of cpdhn1gene (against the housekeeping/control gene, Ubiquitin) was revealed at the first hours of applying the stress (6hr after stress) in the tolerant genotypes while the peak of intensity in the sensitive genotypes, much lower than the peak of the others, was detected later (48hr after stress). As well, the expression of this gene in the resistant genotypes at control conditions was much higher than the sensitive genotype which indicates the readiness of these varieties to cope with drought, constantly. It is supposed that the relative expression of cpdhn1 in the resistant genotypes is initiated sooner and its intensity is higher than the sensitive genotype which shows a late and low induction of the gene. This rapid initiation of the cpdhn1 induction in the tolerant varieties is probably associated with morpho-physiological characteristics (e.g. root traits) which prevent squandering water content of plants through shoot parts under stress condition and achieving rapid tolerance against drought.

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