Analysis of leaf morphology variation and genetic diversity via SRAP markers for near-threatened plant Acer truncatum

To fully protect and utilize Acer truncatum resources, the phenotypic variation and genetic diversity of A. truncatum in different regions should be understood. In this study, leaves of A. truncatum trees from 15 provenances were used as experimental materials to analyze leaf morphological variation and genetic diversity at the molecular level. The results showed that the sizes of leaves of A. truncatum trees from different provenances were significantly different, and there was a certain correlation with the geographical environment: leaf size gradually decreased with increasing longitude, latitude and elevation. According to principal component analysis (PCA), the variation in leaf morphology among provenances concerned mainly the petioles, leaf width, and leaf length; there was no correlation between leaf morphological variation and geographic distance. From 240 pairs of sequence-related amplified polymorphism (SRAP) primer combinations, 12 pairs that met the conditions were identified, and a total of 267 bands were amplified; 252 of the bands were polymorphic, with a polymorphism percentage of 94.38%, and an average of 22.25 bands and 21 polymorphic bands were amplified from each pair of primers. Ne, H and I indicated that A. truncatum has relatively high genetic variation and a rich genetic diversity at the species level. Among the provenances, H and I were 0.1754 and 0.2707 respectively, indicating that the genetic diversity among the provenances of A. truncatum was low. There were differences in genetic diversity parameters among the various sources. Yongji, Shanxi (6) had the highest genetic diversity, and Huixian, Gansu (15) had the lowest genetic diversity. The genetic similarity coefficients among the various sources ranged from 0.8404 to 0.9558, the range of variation was 0.1154, and the average coefficient was 0.9006. The provenance of Taian, Shandong (4) and Yongji, Shanxi (6) had the closest genetic relationship, with a genetic similarity coefficient of 0.9558 and a D of 0.0824; Pingquan, Hebei (2) and Huixian, Gansu (15) were the most distantly related, with the largest D, and a genetic similarity coefficient of 0.8404. Cluster analysis based on the genetic similarity coefficient also showed that the Ds and geographic distances of A. truncatum from different provenances were not correlated. These results provide a reference for research on A. truncatum germplasm management and ecological adaptability.