Detection of Quantitative Trait Loci for Seed Germination Traits in Tomato under Salt and High Temperature Conditions

Abstract

The objective of the experiment was first to evaluate the Recombinant Inbred Lines (RILs) of tomato for seed germination under salt stress, high  temperature and nonstress growth conditions and then to identify quantitative trait loci (QTLs) controlling different germination traits under these  conditions. A total of 101 RILs along with their two parents were tested under three growths. Significant (P<0.05) differences were observed among  the RILs for all germination traits under all growth conditions. Germination was more delayed under salt stress at -0.5 MPa of NaCl than two growth  conditions. Out of all RILs, genotype 291 showed rapidly germinated seed under three growth conditions. The QTL analysis detected a total of 29  significant QTLs for five germination traits under the three different growth conditions. At least 1 to 4 significant QTLs per trait identified explaining  variances ranging from 8.8 to 15.2%. Four significant co-located QTLs were found on chromosomes 9, two of each controlling for onset and rate of  germination traits, each ranging from 9.9 % to 13.2 % per traits under salt and high temperature. Similarly, 12 significant QTLs clustered on  chromosomes 1 and 11 for onset (t10), speed (t50) and the area under the germination curve (AUC) traits under non-stress and high temperature  conditions, ranging from 49.7 to 65.4% .This might be an indication that the common genes control different traits or a locus has pleiotropic effects  that controls multiple traits. Further study is required on Co-located QTL through fine mapping that can identify the candidate genes tolerance to  salt and high temperature conditions which is very useful to improve seed germination and the performance of seed production.