Biochemical and molecular evaluation of some beans genotypes (Phaseolus vulgaris L.) under drought stress conditions

Drought stress is one of the important non-biological stresses for plants such as beans because it affects the growth, development and yield of the plant. Therefore, identification of drought tolerant genotypes is very important. One of the effective ways in identifying drought tolerant genotypes is biochemical investigation and relative genes expression involved in drought stress. Therefore, the present study was performed on a number of bean genotypes including Khomein, COS-16, D81083 and KS-10012 as factorial complete randomized block design. Drought stress was applied at the levels of severe stress (25% field capacity), mild stress (75% field capacity) and normal irrigation (100% field capacity) and then the relative water content, electrolyte leakage, proline, malondialdehyde and gene expression (NCED, CDPK1, PIP1 and NAC) were evaluated. Results showed that the highest and lowest electrolyte leakage traits belonged to Khomein genotypes with 77.66% and COS-16 with 25%, respectively. The highest relative water content of leaf belonged to COS-16 genotype at mild stress of 80.66% and the lowest to khomein genotype at severe stress of 25%. Increasing trend of proline content was observed in all genotypes from 100% of irrigation to mild and severe stresses. Also, increasing trend of malondialdehyde was observed in severe stress compared to control, on the other hand, Khomein genotype with the highest malondialdehyde rank a and COS-16 genotype with the lowest malondialdehyde genotype f were considered with Tukey test. Relative increase of NCED, NAC and CDPK1 gene expression was observed in severe stress compared to mild stress. Different relative expression of PIP1 gene was also observed at different stress levels (75% and 25% of field capacity). In general, it can be concluded that among the genotypes studied, COS-16 had the highest and Khomein genotype had the least tolerance to drought stress.