Mapping Of QTLs For Salt And Drought Tolerance In Recombinant Inbred Line Population Derived From Wild Tomato Solanum Pimpinellifolium During Seedling Stage

With the increased soil salinization and reduced water supply happened more frequently worldwide, drought and salt are becoming the major abiotic stress factors restricting crop sustainable production. Vegetable crops are water and fertilization preferences and the yield and fruit quality are prone to be affected by salt and drought stress. Cultivated tomato(Solanum lycopersicum) as the second most important vegetable crops next to potato over the world is moderate sensitivity to salinity and more sensitive to drought stress. However, the progress on the genetic improvement for salt and drought tolerance is slow mainly due to the narrow genetic background of cultivated tomato. In contrast, the tomato wild species lives in Andes mountain and Pacific Ocean region with disastrous environment and is adaptable to salt and drought after a long evolution. These wild species possess the potential for tolerance to the variouse adversity. Hence it would provide the possibility for the genetic improvement of salt and drought tolerance in tomato crop.In this study, a recombinant inbred line population( F10) derived from S. pimpinellifolium PI365967 tolerant to salt and drought and Solanum lycopersicum Moneymaker, a cultivated tomato was screened during the seedling stage. QTLs for salt and drought tolerance were identified based on the stratigy of the whole genome low sequence( 1.5×) information and a bin-map containing 22,570 bins was constructed. The possible candiditate genes located in these regions were predicated. The molecular mechanisim for salt and drought tolerance was discussed in the genome level. The main results were sumarrized as the following:(1) A RIL population( F10 generation) containing 211 individuals was constructed by single seed descent using Solanum lycopersicum Moneymaker as the femal parent and S. Pimpinellifolium PI365967 as male parent. Huge SNP markers were explored through the whole genome low sequence and a bin-map containing 22,570 bins was constructed.(2) Based on the requencing of the RIL population, 1800 selected bins were used to construct a linkage map in total around 1194.08 cM with an average genetic distance 0.66 cM.(3) RIL population was screened in two years in independent experiment under the stess of 400 mmol NaCl concentration. A significant correlation of the survival percentage was observed with a value 0.687 at 0.01 level. Combing the phenotype data and genentic linkage map, 21 and 22 QTLs were identified respectively by using the methods of MapQTL and GWAS. Among them, 10 QTLs are complete same when two methods were used. Furthermore, three QTLs(Qst1-3, Qst5-4 and Qst7-1) showed consistent through two years and two methods, the contribution rate is 8.3%, 10.3% and 8.4% respectively. Fifteen genes involved in these QTL region were found when compare to the reference genome and they could be classified into recognition and signal transduction genes, transmembrane transport, key enzyme involved in metabolism, enzymes involved in photosynthetic, defensive and regulatory proteins, transcription factors and unknown protein. The further analysis of these candidates hinted that the wild S. pimnpinellifolium might be response to salt stress mediated by MAPKs pathway.(4) RIL population was screened under drought stress with recovery by water after one week. The results showed a significant correlation btween two years with a value 0.453. Combing the phenotype data and genentic linkage map, 21 QTLs were identified respectively by using the methods of MapQTL and GWAS. Among them, 7 QTLs are complete same when two methods were used. Meanwhile Qdt1-4 and Qdt1-10 showed consistent through two years and two methods, the contribution rate is15.0% and 9.8% respectively. Two candidate genes were found within these two QTLs, they are pentatricopeptide repeat-containing protein(Solyc01g100450.1) and zinc finger protein(Solyc01g107170.2).We analysis the salt and drought tolerance of the RIL population and find some QTLs, it will lay a foundation for tomato salt and drought tolerance breeding and the study of other excellent traits of the population.