Differential Expression of CA7 and NCED Genes in Common Bean Genotypes under Drought Stress

The response of plants to drought stress depends on several factors including the plant developmental stage and the length and severity of the stress applied. Common bean (Phaseolus vulgaris L.) is the most important pulse crop that is cultivated worldwide for human consumption. Understanding of the mechanisms responsible for its response to drought is, therefore, essential. An increasing number of reports show that withdrawal of water from plants growing in the controlled conditions is accompanied by changes in the expression of a number of genes. To our knowledge, regulation of gene expression in flower buds of P. vulgaris under stress conditions has not been reported. Our aim was to identify transcription sensitivity of CA7 and NCED genes under water deficit stress at vegetative and reproductive stages of different bean genotypes. Two experiments were carried out. Within each experiment, the groups of drought-stressed plants were subjected to water withholding, while the control plants were watered every other day. Stressed plants were re-irrigated when RWC reached 66±2 percent. Our study showed that CA7 and NCDE were genes differentially expressed in the studied genotypes under drought stress. The expression of these genes was strongly induced in response to drought stress in flower buds of the cultivar Jules and the line KS-21191. It seems that under stress conditions, these genes express more in the tolerant than the susceptible genotypes. Therefore, these two genes could probably be used to obtain plants relatively tolerant to water deficit stress, especially in the reproductive stage of plant growth.