Study On Genetic Relationship And Classification Of Pyrus Plants In Xinjiang

The cultivars resources of pears in Xinjiang were various,and some local cultivars have unknown genetic relationship and differences in classification.In order to find out the genetic relationship and classification of pear cultivars in Xinjiang such as 'Korla fragrant pear',seventy-three pear cultivars or types from Xinjiang were collected and to study the botanical morphological characteristics,pollen microscopic morphological characteristics,chromosome karyotype characteristics and ploidy,genome size,and whole genome resequencing data,analyzes the genetic relationship and classification of pear cultivars in Xinjiang from many aspects,which lays a foundation for further exploring the excellent germplasm and breeding of new cultivars.The results were as follows:(1)48 morphological characteristics were analyzed,and according to principal component analysis,14 factors constitute the difference sources,and the indicators represented include:bud color,petiole length,and weight of single fruit,thousand seed weight and color of annual granches.In the clustering,'Korla fragrant pear','Naxput''Jujuli','Kuikeamut 1','Korla Huangsuanli' and the cultivars of P.sinkiangensis with the closest genetic relationship.'Aiwenqieke','Kuikeamut 2' and the cultivars of P.pyrifolia,P.communis,P.ussuriensis with the closest genetic relationship.'Kotoamut','Heisuanli' and the cultivars of P.sinkiangensis,P.bretschneideri with the closest genetic relationship.(2)The main type of pollen grain exine ornamentation was stripe ornamentation,belonged to the full cover perforation.The cerebroid ornamentation was less,such as 'Ili Hongjujuli','Qipanli','Xuehuali'and'Niitaka'.The porosity of 'Heisuanli','Nanguoli' and 'Manyuanxiang' were less than 0.1 grain/?m2,indicating a place at the beginning of the evolution of pear plants.The porosity of 'Hese Jujuli','Dangshansuli' and 'Tianqiuzi' were the largest,and the degree of evolution were higher.Clustering results show that,'Korla fragrant pear' and the cultivars of P.bretschneideri,P.sinkiangensis,and P.pyrifolia with the closest genetic relationship.'Aiwenqieke' and the cultivars of P.communis,P.sinkiangensis with the closest genetic relationship,'Kotoamut','Korla Huangsuanli','Naxput','Kuikeamut 1'and the cultivars of P.bretschneideri,P.pyrifolia,P.sinkiangensis,P.communis with the closest genetic relationship.'Kuikeamut 2'and the cultivars of P.sinkiangensis,P.ussuriensis with the closest genetic relationship.(3)The test cultivars chromosome size was less then 5.0 ?m,which was a small chromosome,and no satellite was found,most cultivars have 34 chromosomes.With the exception of 'Huocheng Jujuli',the evolutionary trends of local pear cultivars in Xinjiang was generally concentrated,which was in a relatively primitive state.Cluster analysis showed that,'Korla fragrant pear'and the cultivars of P.pyrifolia,P.sinkiangensis and P.ussuriensis,'Jujuli','Kuikeamut 2' and the cultivars of P.bretschneideri,P.ussuriensis,'Kuikeamut 1','Naxput' and the cultivars of P.sinkiangensis,P.bretschneideri,P.pyrifolia,'Korla Huangsuanli' and the cultivars of P.bretschneideri,'Heisuanli','Aiwenqieke' and the cultivars of P.pyrifolia,P.bretschneideri with the closest genetic relationship.Combined with chromosome observation results,'Korla fragrant pear','Kuikeamut 1','Kuikeamut 2','Naxput' were more inclined to P.sinkiangensis.'Jujuli','Korla Huangsuanli'were more inclined to P.bretschneideri.(4)The optimized pear flow cytometry detection following optimization methods:The young leaves of hydroponic annual branches were used as the test material,and woody plant buffer(WPB)was used for dissociation.Filtered by 500 mesh membrane,incubation and centrifugation,propidium iodide(PI)dyeing liquid was added and dye for 10 min without light.Using this method,the genome size of different pear cultivars was measured to be 534.10±72.02 Mb,2C values was 1.09±0.15 pg.The genome size and 2C values of introduced cultivars were slightly smaller than local pear cultivars in Xinjiang and exhibits lower rate of 2C values compared with the others.A total of 4 non-diploids were detected,the diploids exhibits lower rate of 2C values compared with the triploid.The seed length has a certain indicator effect on genome size.Some morphological characteristics of the triploid 'Heisuanli' and 'Aiwenqieke' were consistent with the results of evolution trends analysis.(5)Based on whole genome resequencing,a total of 331.991 G high-quality filtered data were obtained,with an average of 6 775.324 M per sample.A total of 4 593 531 high-quality SNP loci were detected,the polymorphism of pear cultivars in this experiment was abundant.The differentially expressed genes between them may be related to the changes in 17 genes,and there were 28 enrichment pathways.'Korla fragrant pear','Kuikeamut 1','Jujuli'and the cultivars of P.sinkiangensis with the closest genetic relationship.'Kotoamut','Naxput','Aiwenqieke','Heisuanli','Kuikeamut 2','Korla Huangsuanli' and the cultivars of P.communis with the closest genetic relationship.According to the comprehensive analysis,'Korla fragrant pear','Kuikeamut 1','Jujuli','Kotoamut',Naxput','Kuikeamut 2' and 'Korla Huangsuanli' should be classified into P.sinkiangensis.