Biochemical Impact Inflicted by Aphid Induced Urdbean Leaf Crinkle Disease (ULCD) Infection on Different Blackgram Genotypes

Aims: To investigate the variations in total protein content and anti-oxidative enzymes in blackgram genotypes showing various levels of resistance against aphid-mediated Urdbean leaf crinkle disease (ULCD).

Study Design: Completely Randomized Design.

Place and Duration of Study: The studies were carried out at the Insectary belonging to the Department of Agricultural Entomology and the Centre of Innovation at Agricultural College and Research Institute, Madurai, Tamil Nadu, India in January 2021.

Methodology: The research was conducted on seven blackgram genotypes exhibiting different levels of resistance to ULCD. A pot culture study was established and the test plants were subjected for inoculation of urdbean leaf crinkle virus (ULCV) via feeding by 10 viruliferous Aphis craccivora adults/plant. The alterations in the total protein content, superdioxide mutase (SOD), catalase (CAT) and peroxidase (PO) activity was estimated using spectrophotometric methods in comparison to healthy genotypes on 0, 15 and 30 days after inoculation (DAI).

Results: No discernible increase in the levels of protein content was seen in either of ULCV inoculated or un-inoculated genotypes on the day of the inoculation. At post inoculation, leaf protein content of ULCV highly susceptible genotypes (VBN 8 and T9) was only marginally higher than that of resistant genotypes (CO 5 and CO 6), whereas in moderately resistant genotype (APK 1) it had only slightly increased. The SOD activity showed only a non-significant drop between inoculated versus un-inoculated plant leaves in highly susceptible VBN 8 and T9 genotypes. At 15 and 30 days post inoculation, a significantly less SOD activity was observed, but PO inversely increased compared to the latter under ULCV inoculated versus un-inoculated conditions in ULCV resistant CO 5 and CO 6 genotypes. While the susceptible ADT 5 and ADT 6 and highly susceptible VBN 8 and T9 genotypes did not show any significant increase in PO levels between inoculated versus un-inoculated conditions. Interestingly, ULCV inoculation considerably decreased the reduced CAT activity both in resistant and susceptible genotypes, when compared to the un-inoculated healthy ones.

Conclusion: Fluctuations in the levels of antioxidant enzymes as well as the total protein content was significant only at 15 Days post inoculation. The ULCV infection tends to increase the total protein content in inoculated plants compared to un-inoculated plants. The aphid transmission of ULCV infection in different blackgram genotypes inflicted considerable increase in PO while decrease in SOD and CAT activities in resistant CO 5 and CO 6 genotypes.