Analysis Of Quality And Genetic Diversity Of Crispy Plums In Sichuan And Chongqing District

Plum is an important cultivated fruit tree in China.Crispy plum series are the main type of fruit trees in Sichuan and Chongqing with wide distribution,large cultivation area and high yield.Crispy plum,as one important category of plum trees,has a wide range of cultivated varieties.Meanwhile,it not only has many subtypes with confusing names,but also has the phenomenon of synonyms and homonyms.In addition,some local breeds have no scientific names around the world.Most of the research have reported about the cultivation management and botanical traits of crispy plum trees,but a few studies have reported on their genetic relationship between varieties.It brings many inconveniences to the preservation and utilization of different crispy plum varieties in Sichuan and Chongqing.This study aims to explore local genetic varieties and study the genetic relationship between varieties.Meanwhile,this study provides critical methods and references of germplasm collection,scientific classification,resource development,resource utilization,excellent varieties breeding(such as parent selection,selection,etc.),as well as industrial promotion.We selected 20 varieties of crispy plums that were mainly cultivated in Sichuan and Chongqing in this experiment,and used SSR(Simple Sequence Repeat)molecular marker technology to study the molecular level among the varieties.The purpose is to explore the genetic relationship among the varieties through molecular level genetic diversity analysis.At the same time,the differences between the varieties were analyzed in combination of botanical traits and physiological qualities.The 15 pairs primers with good polymorphism from 70 pairs of SSR primers were used to scan 20 samples by high-throughput fluorescence capillary electrophoresis platform.The polymorphism of 15 SSR loci and genetic diversity of 20 samples were evaluated via the software PopGen32,and the dendrogram of these accessions was constructed by using the MVSP program.Measuring and comparing the main appearance indicators of fruits of various varieties(such as fruit weight,horizontal and vertical diameter,color,hardness)and nutrients(such as soluble solids,sugar,acid,vitamin C content).Analyzed the index differences between the varieties and the correlation between the indexes by Microsoft Excel and SPSS18.0 software.There are the results of this study:1.A total of 130 alleles(Na)were detected in these accessions,and the average number of alleles was 8.67.There were 63.91 effective alleles(Ne)in the entire population,with the per locus was 4.26.The average expected heterozygosity(He)was 0.748,the average observed heterozygosity(Ho)was 0.831,and the mean Shannon 's diversity index(I)was 1.495,suggesting the tested plum germplasm resources had a high genetic diversity.2.The genetic variation of 20 cultivers ranged from 0.158 to 0.919.Among them,Eldordo and Wanzhouqingcui plum had the lowest genetic identity and distant phylogenetic relationship.Meanwhile,Eldordo had the highest genetic identity with Nai plum as well as the closest phylogenetic relationship.JincuI plum and Maoxianda plum had the highest genetic identity and the closest phylogenetic relationship.The tested plum germplasm resourcesd could be classified into two groups.Among them,Eldordo had a close phylogenetic relationship with Nai plum,Cuihong plum.There was a same situation among Yinhong plum,Jiang'anqingcui plum,Dabai plum,Jincui plum,and Maoxiandaplum.Based on the analysis results of SSR markers,it could be seen that some green crispy plums had a close phylogenetic relationship,but there was no phenomenon of synonyms.This research also confirmed that the importing cultivars abroad were closely related to Japanese plums(Prunus salicina Lindl).3.The results of the main appearance traits of the fruit showed that all the tested varieties are off-core and crispy.According to the color of the peel,it could be divided into 4 categories,red plum(Eldordo,Fenghuang plum),red-green plum(Yinhong plum,Cuihong plum,Yubeiwanshu plum),red-yellow plum(Huanggan plum),14 green-yellow peel of plums.According to the fruit shape index,it could be divided into 3 categories.And according to the single fruit weight,it can be divided into 4 gradients.4.The correlation analysis results of the main physiological quality indicators indicated that the higher total sugar content was in the fruit,the higher sugar content and vitamin C content would be achieved in the fruit.The a* in fruit color difference was significantly negatively correlated with the total sugar content(r =-0.469 *).The horizontal and vertical diameters of the major fruit were also large,and the three values of L*,a*,and b* in the color difference measurement result also showed a very significant positive correlation.When the fruit sugar-acid ratio is higher,the fruit quality and the flavor will be better.5.Combining with the main appearance qualities and nutrients of comprehensive indicators,those 7 cultivars(Dabai plum,Fengtang plum,Fendaicui plum,Wushancui plum,Jang'anqingcui plum,Fenghuang plum,Jincui plum)were comparable with other varieties.They were suitable to popularize and cultivate in Sichuan,Chongqing district and surrounding areas.Among them,there were 4 cultivars varying maturity period :early-middle-maturing(Dabai plum),middle-maturing(Wushancui plum),middle-late-maturing(Fendaicui plum),late-maturing(Jincui plum).And they could be further evaluated as the target excellent introduction varieties.