Biochemical changes in bitter gourd in response to low temperature stress

The present study investigated the effect of low temperature stress on biochemical parameters in fifteen days old seedlings of bitter gourd genotypes. The seedlings were exposed to 10°C and 5°C for seven days and assessed for recovery at 25°C. For acclimation, the seedlings were exposed to temperatures from 20°C to 5°C decreasing at the rate of 2°C/hr before LT exposure. Leaf samples were collected at different days post exposure, post recovery and analysed for biochemical parameters. Survival percentage of seedlings of PAUBG-56 was 10.7% higher than that of Punjab-14 at 5°C. Phenylalanine ammonia-lyase activity, total phenols, flavonols, total proteins were significantly (CD at 5%) higher in PAUBG-56 as compared to Punjab-14 seedlings. New protein bands in the range of 12-62 kDa were observed in SDS-PAGE in both the genotypes, which might be involved in defence against stress. At seedling stage, both the genotypes showed resilience to cold stress, though it was observed to be higher in PAUBG-56. Cold stress caused increase in phenolics and related enzymes in the seedlings. Acclimation improved cold tolerance in fifteen day old seedlings of both the genotypes.