Tomato near isogenic lines to unravel the genetic diversity of S. pimpinellifolium LA0722 for fruit quality and shelf life breeding

Abstract

The introgression of genes from the wild species S. pimpinellifolium has the potential to improve tomato commercial varieties for numerous fruit quality traits. One of particular interest for fresh-market tomatoes is long shelf life (SL). Twenty-two near isogenic lines (NILs) were developed in three to four backcrosses using S. pimpinellifolium accession LA0722 as the donor parent, based on phenotypic selection for long SL and using a set of 28 SSRs for marker assisted selection. A total of 30 QTLs for fruit quality were found and 18 were subsequently validated in previous generations. A two year trial of the NILs homozygous for the LA0722 introgressions showed several novel QTLs. Fruit quality QTLs revealed an increased effect promoted by LA0722 alleles. A SL QTL was found on chromosome 9 and was consistent both years. A wild introgression on chromosome 3 showed a stable QTL for increased firmness and for yellow fruits. Therefore, the wild introgressions provide a source of variation with positive effects in fruit traits of commercial value. While obtaining new varieties, this strategy provided an effective method that integrates the QTL analysis and the prediction of positive alleles in wild germplasm.