Exploitation of Genetic Variation for Seed Germination Traits Under Salt Stress and High Temperature in Recombinant Inbred Lines of Tomato

Abstract

Unfavorable environmental conditions such as salt stress, drought and extreme temperature can affect tomato growth and final yield. But, natural genetic variation exists among tomato cultivar and related wild species for tolerance to abiotic stresses. The objective of this experiment was to evaluate the recombinant inbred lines of tomato for seed germination traits under salt stress, high temperature and non-stress growth conditions. A total of 101 recombinant inbred lines along with their two parents were tested in a randomized complete design with two replications under salt stress, high temperature and non-stress conditions. Significant (P<0.05) differences were observed among the recombinant inbred lines for all germination parameters under all growth conditions. Higher genetic variation was observed under stress than non-stress condition due to exposed to stress environment. Germination was more delayed in salt stress at -0.5 MPa of NaCl than in high temperature stress of 35 ⁰c and non-stress conditions. But, the magnitude of response to stress varied among the recombinant inbred lines of tomato. In most cases, average germination trait values of the recombinant inbred lines were intermediate between the values of the two parents across the three growing conditions. However, transgressive segregation was also observed in the population which could due to combination of alleles from both parents for the expression of the studied phenotypes. Out of the 101 recombinant inbred lines, about five and three number of genotypes showed faster and earlier to uniform seed germination under salt and high temperature respectively. Overall, a recombinant inbred line of 291 showed faster seed germinated and performed almost for all germination traits than related wild species of pimp under three growth conditions. This genotype may be selected at early stage tomato establishment under both stress conditions. Furthermore, exploring from wide array of genetic variation and underlying the mechanism response to stress can help breeding for abiotic tolerance.

Keywords: Germination, genetic variation, salt stress, high temperature, tomato