Genetic Linkage Map Construction And Gene Localization Of Agronomic Traits In Pear(Pyrus L.)

China was one of Pyrus genus provenances,Chinese pear played an important role in fruit production.Genetic linkage map of pear(Pyrus L.)was constructed based on AFLP and SSR markers with F1 segregation population,the mapping parents that Yali and Jingbaili were good characters.19 agronomic traits were investigated and analyzed,the Quantitative Trait Loci(QTL)linked to 19 agronomic traits with interval mapping were located in the map.The main research results were as follows:1 F₁ hybrid individuals were identified by AFLP silver staining technique from 150 Yali progenies,145 F₁ segregating population of Yali×Jingbaili were confirmed to construct linkage map and scored for marker polymorphisms,454 AFLP markers generated by 40 MseI/EcoRI primer pairs.2 SSR conditions on pear were optimized,which established SSR reaction optimization system,and 41 SSR markers generated by 18 primer pairs were used to constructed genetic linkage map.3 A high density genetic map was constructed using Joinmap3.0 setting CP(cross pollination population)type data based on 454 AFLP markers and 41 SSR markers,372 AFLP markers and 34 SSR markers were located on 18 linkage groups,covering a total distance of 1395.9cM of pear genome,with an average distance of 3.8cM between adjacent markers.The LOD value of every linkage group was between 4.0～7.0.4 The Quantitative Trait Loci(QTL)linked to 19 agronomic traits was analyzed with MapQTL4.0 software using interval mapping method,83 putative QTLs was located in the genetic linkage map.2 QTLs were for leaf-exapation period trait,38 QTLs were for 9 leaf traits,36 QTLs were for 8 growth traits,7 QTLs were for pear scab.Among 83 putative QTLs involved 72 QTLs with distance from the nearest AFLP or SSR marker between 0.0 cM and 2.0cM,61 QTLs with distance from the nearest AFLP or SSR marker were between 0.0cM and 1.0cM.Total number were 27 QTLs with major effects(LOD≥3.5).5 46 QTLs were located on 8 linkage groups that were two or more QTLs for co-located or closely linkage(with distance from the nearest QTL was between 0.0cM and 5.0cM),total number were 16 QTLs with major effects(LOD≥3.5).The most regions for co-located or closely linkage QTLs were on LG15,and the co-located or closely linkage QTLs number was thirteen.Genes would cluster together on the linkage groups for their similar functions,the research showed LG4,LG8 and LG15 were related to the leaf traits; LG4 and LG16 were related to growth traits;7 QTLs related to pear scab fell onto 5 linkage groups;2 QTLs for leaf-exapation period trait were distributed at top or tail of related limkage groups.These results would be useful for spreading Pyrus genus resources and marker-assisted selection for genetic improvement in Pyrus.