Abstract
Urdbean leaf crinkle virus (ULCV) is a widespread and most destructive virus that causes leaf crinkle disease in black gram. Virus infection causes alteration in physiological and biochemical processes within the plant. In present study, effect of viral infection was investigated on chlorophyll content, total soluble sugar, total protein, phenolic contents, sodium dismutase (SOD) and nitrate reductase activities in the leaves of susceptible and resistant genotypes of urdbean at 30 days after virus inoculation. Disease symptoms were mild (6.7% to 10%) in resistant genotypes and severe (36% to 43%) in susceptible genotypes. ULCV infection resulted in a significant decrease in chlorophyll content in infected plants of all genotypes over control plants; however, magnitude of reduction was more in susceptible genotypes (41%) as compared to the resistant genotypes (14.35%). The total sugar and protein contents were significantly higher in the inoculated susceptible (210.26 % and 68.67%, respectively) as compared to the resistant genotypes (183.87% and 25.89%, respectively). Also, the total phenolic content was significantly higher in inoculated resistant genotypes (83.91%) over the susceptible genotypes (25.89%). There was significant decrease in the activity of superoxide dismutase enzyme in resistant genotypes as compared to susceptible inoculated genotypes. Similarly, a reduction in nitrate reductase activity was more in inoculated plants of resistant genotypes. Our results indicate that post-infection significant increases in total sugars and proteins in susceptible genotypes and phenols in resistant genotypes may have a role in disease resistance and development. Changes in enzymatic activities in resistant and susceptible genotypes might also have some role in resistance against ULCV.