SSR Marker Based Genetic Diversity and Fusarium Wilt Resistance Screening of Tomato (Solanum lycopersicum L.) Genotypes

Fusarium oxysporum is one of the devastating diseases of tomato (Solanum lycopersicum L.) causing high yield losses in fields and commercial greenhouses, inferring necessity for development of disease resistance. An research experiment was laid out with 23 diverse genotypes including susceptible check at research farm during wet season-2018 for screening of tomato genotypes for fusarium wilt resistance. Phenotypic screening of 23 genotypes revealed varied disease resistance as highly resistant (AVTO1219 and EC631), resistant (Pant bahar, EC620428, EC620378, EC631369 and EC620503), moderately resistant (EC615055, EC620389, EC620394, EC620422, EC620406 and AVTO9803) and moderately susceptible (PKM1, EC620382, EC620427 and EC620395) over the highly susceptible checks (Pusa Ruby, Arka Vikas). Employing 95 SSRs for molecular profiling resulted in 33 polymorphic markers, 58 monomorphic markers and remaining 4 markers as unamplified. A total of 74 alleles were detected using 33 polymorphic markers with an average allele number of 2.24 for each marker. Two markers viz., TES60 and TGS633 produced maximum (4) alleles. The polymorphic information content (PIC) value ranged from 0.28 to 0.76 with an average of 0.53 and marker TGS633 was found to be the most suitable marker with the highest PIC value. Cluster analysis through UPGMA method classified twenty three genotypes into five clusters and the coefficient among 23 genotypes was varied from 0.5 to 0.86. Over all, EC631379, EC631369, EC620428, EC620378 and EC620503 were identified as new resistant genetic resources against Fusarium wilt at both phenotypic and genotypic level with the presence of I-2 gene loci. Based on the results, the identified genotypes can be further tested and be used in Marker Assisted Selection or gene pyramiding programs to develop disease resistant commercial cultivars.