Twenty five tomato (Solanum lycopersicum L.) genotypes were subjected to genetic diversity analysis using twenty SSR markers. Out of 20 markers used, 14 SSRs were polymorphic and a total numbers of 22 SSR alleles were generated by 14 SSR markers, out of which 19 were polymorphic and 3 were monomorphic, with an average of 1.57 alleles per locus. The range of amplified products was 100-400bp approximately. Jaccard's similarity coefficient varied from 0.65 between germplasm EC519821 and CO-3 to a maximum of 1.0 between genotypes EC519769 and DARL-66, with an average value of 0.83. Cluster analysis based on Jaccard's similarity coefficient using the unweighted pair-group method with arithmetic mean (UPGMA) revealed 2 distinct clusters, A and B, comprising 1 and 24 genotypes respectively and at 75 and 78 per cent similarity, respectively. The genotypes which showed similar morphological and genetic trends were grouped more or less together in both these cases were a few. Cluster A comprised most diverse germplasm (EC519821)belongs to pimpinellifolium wild species with similarity coefficient 0.65% and differentiated with other cultivated species.Cherry Tomato and Cherry-2 were trends in similar cluster similar with approximately 96% similarity.SSR markers were able in in differentiating the genotypes based on morphologically and genotypically.However, the grouping of 25 genotypes were independently of geographic distribution.The genetic distance information found in this study might be helpful to breeder for planning among these genotypes.

No abstract

Tomato leaf curl Bangalore virus (ToLCBaV), a monopartite begomovirus transmitted by the whitefly Bemisia tabaci, has become a major constraint in tomato production in the Indian subcontinent. Earlier breeding efforts in India led to the adoption of tomato cultivars carrying the resistance gene Ty‐2. However, it has been observed recently that such cultivars/hybrids are susceptible to begomoviruses. This requires the identification of additional or new sources of resistance against ToLCBaV. The present study was undertaken to assess the effectiveness of several Ty genes in providing resistance against infection by ToLCBaV. The kinetics of virus multiplication in different Ty resistance gene stocks of tomato were estimated and compared using quantitative PCR data. Accumulation of viral genomic units and symptom severity were lower in tomato lines carrying Ty‐3 and Ty‐2 + Ty‐3 compared with those carrying Ty‐2 alone. All tested lines carrying Ty‐2 showed typical tomato leaf curl disease symptoms. Tomato lines carrying Ty‐2 + ty‐5 and ty‐5 + Ty‐6 combinations had a significantly higher disease severity index and viral genomic units compared to those carrying Ty‐3 and Ty‐2 + Ty‐3 at 30 days postinoculation. The accumulation level of ToLCBaV genomic units serves as a good indicator for resistance selection along with other parameters of disease. We present here a comprehensive overview of the effectiveness of Ty‐2, Ty‐3, and ty‐5 alone as well as the combinations Ty‐2 + Ty‐3 and Ty‐2 + ty‐5 against ToLCBaV.

No abstract