Objective In this study, the F₁ population of two cultivars of plum (Prunus salicina L.) in Northeast China, Jilin 6 and Longyuanqiuli, were used as research materials, and the correlation analysis and QTL mapping of six fruit traits (weight of single fruit, transverse diameter of fruit, vertical diameter of fruit, fruit shape index, thickness of pulp and content of total sugar) were carried out.

Method SPSS 23.0 software was used to analyze the phenotype and correlation of 6 fruit traits. QTL analysis of fruit traits with normal distribution was carried out by Map QTL 5.0 software. QTL was located according to interval mapping method. Finally, the linkage group of QTL was mapped by Map Chart 2.3 software.

Result The variation coefficient of 6 fruit traits was 6.09%-35.98%. The phenotypic data of transverse diameter of fruit, vertical diameter of fruit and thickness of pulp showed normal distribution. There was a significant positive correlation between weight of single fruit and transverse diameter of fruit, and the correlation coefficient was 0.959. The transverse diameter of fruit was significantly positively correlated with vertical diameter of fruit and thickness of pulp. There was a significant or extremely significant negative correlation between content of total sugar and other indicators. A total of 11 QTLs related to fruit traits were detected, including 4 QTLs related to transverse diameter of fruit, 4 QTLs related to vertical diameter of fruit, and 3 QTLs related to thickness of pulp. All QTLs were distributed on linkage groups LG2, LG3, LG8 and LG15. Among them, 3 QTLs related to fruit traits were detected on linkage groups LG2, LG3 and LG15. The LOD values were 2.46-3.58, which could explain 9.8%-14.4% of phenotypic variation.

Conclusio There were correlations among the fruit traits of plum in Northeast China, and there were clusters of QTLs loci on linkage groups, which provided a theoretical basis for molecular assisted breeding of plum in cold region.