Population structure analysis and marker trait association in selected set of Indian tomato ( Solanum lycopersicum L.) varieties under high temperature condition

Heat stress is an important abiotic stress affecting the productivity of tomato. Understanding the physiological basis of heat tolerance is needed to adapt to the current or future heat stress. Thus this study was undertaken to evaluate the phenology, physiology, biochemical and yield parameters of twenty-two contrasting tomato accessions when exposed to high temperature stress and to identify SSR markers associated with these traits. The experiment was laid out in completely randomized design with two treatment levels i.e. control and high temperature stress (36 ± 2 °C) with three replications each. The high temperature stress was induced from flower initiation to maturity stage by keeping the pots in a temperature controlled green house facility for 45 days. Twenty five SSR primers were employed to analyze genetic diversity and population structure among 22 tomato accessions collected from different eco-geographical regions of India. SSR markers proved to be more informative in genetic diversity assessment. These accessions showed significant genetic variability for physio-morphological and yield traits under both control and high temperature condition. Clustering by average linkage method was done to establish a relationship among the 22 tomato accessions. All the accessions were clustered into mainly three clusters. Principle component analysis revealed that, the first principal component revealed 43.39 per cent variation, while the second component showed 12.93 per cent variation under high temperature condition. Principle co-ordinate analysis evidently differentiated the accessions to three main groups based on genetic relatedness. Population structure analysis also obviously separated the accessions to four sub populations.GLM analysis identified 10, 9 highly significant marker traits association under high temperature and control condition respectively. Among them, RM270, SSR605 and RM356 were linked to more than one traits. Identified tolerant accessions and molecular markers can be utilized for developing high yielding high temperature tolerant tomato varieties in breeding programmes.