Groundnut late leaf spot disease caused by Phaeoisariopsis personata (Berk. & Curt.) is an most destructing biotic constraint for the groundnut production. Early leaf spot and late leaf spots, together can cause losses in pod yield of upto 60 percent and reduce the quality of the pod and fodder. To fulfill the need and challenges of edible oil demand and saving the expenditure on import of foreign edible oil, we need to increase the oilseed production through minimizing the biotic and abiotic stress losses. Identification and transfer of resistance source gene to develop advance breeding lines is one of the primary objective for resistance breeding in groundnut. Present experiment was carried out to understand the inheritance pattern of late leaf spot disease by using disease scoring scale at 90 to 100 days stage of maturity. The resistant parent Phule Unnati was crossed with susceptible SBXI recipient parent and different advance generations were scored as per 0 to 9 scale. The screening of generations like Parent (P1, P2) and generations like F1, F2, BC1 and BC2 was done at open field condition to know the disease reaction. The segregation pattern of F2 and back crossed generation revealed that resistance to late leaf spot is controlled by a single recessive gene and segregated in 15(Susceptible):1(Resistant) ratio. The 15:1 ratio indicates that the gene interaction involved for disease resistance was duplicate type. Genetics of late leaf spot disease resistance in groundnut and will aid groundnut breeders to develop a strategic late leaf spot disease resistance breeding program and to map the genes governing resistance.

Late leaf spot, duplicate gene interaction, F2 segregating population

The present investigation indicated better combinations like cross SBXI × Phule Unnati, associated with late leaf spot resistance. The parent Phule Unnati were found to be superior parents in contributing to late leaf spot resistance as well as pod yield and its component traits. The identified late leaf spot resistant plants obtained in F2 shall be utilized for development of resistant variety in groundnut. The results of the present study have important implications for breeding programs which aim to deploy LLS resistance genes or stack different genes conferring resistance to different pathotypes of LLS into elite cultivars. According to Thakur et al. (2008), pyramiding of genes is a strategy to develop varieties with durable DM resistance in cereal crop. The stacking of resistance genes with major effects delays the appearance of new races of the pathogen. The basis for this stability of resistance is the decrease in pathogen fitness when a number of virulence genes are necessary to overcome the resistance of the host (Van der Plank, 1984). Therefore, a potential strategy in order to maintain disease resistance for a long period of time would be the introgression of several resistance genes in a single variety. The data obtained in the present study demonstrated that the breeder should choose a number of sources having different resistance genes for gene pyramiding, in order to put together in the best possible combination of genes in new cultivars. Therefore, these varieties expressing durable resistance would be resistant to a large number of pathotypes of the pathogen over a long period of time. However, more studies are required to identify different resistance genes (non-allelic) for their spatial and temporal deployment.

Tukaram Sadgar, Viju Amolic, G. C. Shinde, S. R. More, R. T. Gaikwad, M. R. Patil, Puja Mate and Ramchandra Navatre (2023). Genetic model of Inheritance of Late leaf spot resistance in Groundnut (Arachis hypogaea. L). Biological Forum – An International Journal, 15(11): 456-460.