Biochemical Basis of Resistance to Sterility Mosaic Disease in Pigeon Pea Genotypes

Background: Sterility mosaic is the most destructive disease of pigeon pea causing yield losses up to 95 per cent. Pigeon pea genotypes are found to vary in different biochemical characteristics, thereby playing a crucial role in resistance to sterility mosaic disease. The best approach to manage the disease is by adopting resistant genotypes for cultivation, which is highly necessary in the areas with high sterility mosaic incidence. Methods: Field screening of 41 pigeon pea genotypes was conducted during Kharif 2021 and 2022 at the Indian Institute of Pulse Research, Regional Research Center, Dharwad, to identify the resistance sources to Pigeon pea sterility mosaic virus. All the test genotypes were artificially inoculated by leaf stapling technique at 15-20 days after sowing and the infector hedge row technique was also employed to develop high disease pressure. Observation on per cent disease incidence was recorded at the peak period of the disease. The study also focused on biochemical components that confer resistance in pigeon pea. Further, the leaf samples were collected from the selected pigeon pea genotypes showing resistance and susceptible reactions and statistically analysed for total phenol content, peroxidase and polyphenol oxidase activity. The genotypes showing resistance and susceptible reactions were analysed for leaf chlorophyll content using SPAD Meter. Result: Seven genotypes were found resistant to sterility mosaic disease with a mean disease incidence of 1.9-8.86 per cent. SPAD Chlorophyll Meter Reading revealed that chlorophyll content remained high in all resistant/moderately resistant genotypes as compared to susceptible genotypes. The resistant genotypes were shown to have higher phenol content, peroxidase and polyphenol oxidase activity in comparison to susceptible genotypes suggesting their crucial role in imparting resistance.