Effect of Water Stress on Expression of a 20 kD Cyclophilin-like Protein in Drought Susceptible and Tolerant Cultivars of Sorghum

Immunodetection studies revealed the presence of a 20 kD cyclophilin-like protein (designated as SorgCyp20) in leaves and seeds of sorghum (Sorghum bicolor L Moench). The expression of SorgCyp20 was temporally regulated in the leaves and after attaining maximum levels at either 60 or 70 days after sowing it declined after flowering. The effect of drought stress on SorgCyp20 levels in the leaves and seeds of sorghum was stage and cultivar dependent. The drought stress-induced enhancement in SorgCyp20 levels was many times higher in the leaves (3-fold increase at 30 days after sowing) and seeds (2.5-fold increase at 9 days post anthesis) of drought tolerant cv ICSV-272 than in the drought susceptible cv SPRU-94008B. The intercultivar differences in drought stress-induced changes in SorgCyp20 expression were not related to the difference in water potential thus suggesting differential regulation of SorgCyp20 in response to stress in the two sorghum cultivars.