Aims Armeniaca mandshurica is an important species which serves the need of ornamental, wood and other economical uses. This species has been in wild or semi-wild state for a long time and few studies about this species have been conducted. This paper aimed to provide an important reference for the collection, evaluation and protection of germplasm resources of A. mandshurica.
Methods The status of the germplasm resources in the main distribution area of A. mandshurica was investigated. In total, 47 typical sample trees from Liaoning, Jilin and Heilongjiang Provinces were selected. For each tree, 22 quantitative traits and 7 qualitative traits were measured. The diversity of quantitative traits was represented by indicators such as coefficient of variation, and the diversity of qualitative traits was represented by indicators such as frequency distribution. Trend surface analysis was used to explore the geographical variation in the quantitative traits. A total of 115 pairs of SSR primers were used for PCR amplification for 47 A. mandshurica germplasms, and the genetic diversity of A. mandshurica germplasms was analyzed using genetic similarity coefficient. Germplasms were classified by cluster analysis based on phenotypic traits and SSR markers separately.
Important findings High phenotypic diversity was found among different germplasms in A. mandshurica. The coefficients of variation (CV) of the 19 quantitative traits ranged from 9.40% to 55.98%. Among the 19 traits, twig length had the highest CV and kernel width had the lowest CV. The Shannon-Wiener index of 7 qualitative traits ranged from 0.58 to 1.22. Due to the significant correlation between geographical locations and main climatic factors within the study area, the quantitative traits of A. mandshurica germplasms were closely related to their geographical locations. Among them, twig length increased from east to west, twig thickness and seed mass increased from north to south, and fruit handle length increased from northeast to southwest. Twig length and fruit handle length were positively correlated with altitude, twig thickness was negatively correlated with altitude, and seed mass was not correlated with altitude. Clustering analysis based on 26 phenotypic traits showed that the 47 A. mandshurica germplasms could be divided into 4 categories, which mainly reflected the difference of the germplasm characteristics in A. mandshurica and to some extent also reflected the difference of germplasm productions. Clustering analysis based on genetic similarity coefficients showed that the 47 A. mandshurica germplasms were also divided into 4 categories, which reflected the difference of germplasm productions. Chi-square test showed that the correlation between the two clustering results was not significant, and that the external environment was the key factor affecting phenotypic variations in A. mandshurica.