Genetic Evaluation and Molecular Markers for Heat Tolerance in Tomato (Lycopersicon esculentum Mill.)

Genetic evaluation was performed on twenty three genotypes of tomato (Lycopersicon esculentum Mill.) under high temperature at summer season to determine the variation between them for heat tolerance. Heat tolerance related criteria, i.e., pollen viability, fruit setting, osmotic pressure and fruit yield per plant.  LSSS1, Homestead 24, Black Russian Plum, Super Marmand and Money Maker possess more tolerance of heat. In contrast, Super Stain B, Castle Rock, Cherokee Purple, Moskvich and Nicholevna Pink were more susceptible of heat. The pollen grain viability and fruit setting criteria consider as suitable morphological markers for heat tolerance than other heat tolerant related criteria as osmotic pressure. Heritability was high and moderately whereas, the genetic improvement of new strains could be done. From previous evaluation, Lsss1 as tolerant line and Super Strain B  as sensitive cultivar of heat tolerance was crossed for study of molecular markers related to heat tolerance by using bulk segregate analysis (BSA). Crossing was carried out between these two genotypes to obtain the F1seeds which were left for selfing to obtain the F2 seeds. The two selected genotypes, their F1 and F2 plants were evaluated for their response to heat stress by recording some heat stress related traits. Bulk of the two extremely F2 plants (most tolerant and most sensitive F2 groups), the two contrasting parents and their  F1, were used to develop some molecular genetic markers associated with heat tolerance in tomato by using ten RAPD and six ISSR primers. two RAPD markers (with molecular sizes of 100 bp for primers A16 and 500 bp for primer Z13) and one ISSR marker (with molecular size of 650 bp) were considered as reliable markers for heat tolerance as well as susceptible genotypes possessed eight RAPD markers (with molecular sizes 500 and 1500 bp for primer C02, 1750 and750 bp for primer C03, 2400 bp for primer C05, 550 bp for primer C08, 400 bp for primer C14 and 650 bp for primer C15). [Journal of American Science 2010; 6(12):364-374]. (ISSN: 1545-1003).