Investigation And Diversity Evaluation In Situ Of P.calleryana In China

Pyrus calleryana Decne is one of the most ancestral pear species,native to China and widely distributed in Shandong,Henan,Jiangsu,Zhejiang,Jiangxi,Anhui,Hubei,Hunan,Fujian,Guangdong and Guangxi,and also distributed in northern Vietnam.Suitable for warm and humid climates,P.calleryana is a multi-purpose tree species with medicinal,timber and ornamental value.P.calleryana is one of the common rootstocks of pear trees in southern China,which is affinity with Chinese pears and western pears.It plays an important role in rootstock breeding.However,in recent years,due to environmental changes and human activities,the number of wild resource populations and individuals of pears decreased sharply,and even showed an obvious trend of disappearance.Therefore,it is an urgent need to grasp the distribution status of P.calleryana populations,evaluate their genetic diversity and protect them.Also,it is urgent to grasp the distribution status of wild pears,evaluate their genetic diversity and protect them.In order to protect and utilize the P.calleryana resources in China,the distribution of P.calleryana resources in China was investigated comprehensively in this paper.The GIS-based germplasm resource information was set up,and the distribution areas and characters of P.calleryana were studied in this paper.Based on the comprehensive investigation and collection of germplasm resources,the phenotypic characters of 78 P.calleryana accessions were analyzed.The main conclusions are as follows:1.Maximum entropy model(MaxEnt)and geographic information system(GIS)were used to predict the potential distribution areas of P.calleryana.They are mainly concentrated in southern China between 20 °and 105 °E,including Hunan,Hubei,Jiangxi,Fujian,Zhejiang,Guangdong,and Hunan,Hubei,Jiangxi,Fujian,Zhejiang and Guangdong provinces.Guangxi,Anhui and Jiangsu are the best suitable habitat areas.Both the Annual Mean Temperature and Annual Precipitation are the decisive factors affecting the distribution of P.calleryana,and the Temperature Seasonality also has an obvious effect on the distribution of suitable habitat areas of P.calleryana.2.P.calleryana in China is distributed in 16 provinces and autonomous regions.The geographical distribution ranges from 21.86 °to 36.18 °N and from 98.66 °to 120.64 °E.The meteorological elements,landform,site type,agrotype,vegetation form,slope direction,slope site,slope gradient,traffic condition,disturb status and other factors also affect the distribution areas and numbers of P.calleryana.3.There are many variations in the branches,leaves and fruits of P.calleryana,and the variation mainly comes from population space.With the change of geographical and ecological factors,the variation of P.calleryana accessions also showed a certain regularity.The phenotypic characteristics of the plants are the result of the combination of environment and heredity.The changes in environment often lead to some changes in phenotypic characters of P.calleryana,while similar geographical environments often lead to similar genetic variations among materials.The results showed that there was a high correlation between cluster results of P.calleryana and geographical distribution pattern of their populations.