Abstract:

【Objective】 This study aims to understand the leaf phenotypic diversity of holly (Ilex spp.) germplasm resources, elucidate the mechanisms behind this diversity, and support the introduction, cultivation and breeding of new varieties. 【Method】 We observed 18 phenotypic traits across 42 holly germplasm resources and analyzed the phenotypic variation using differential analysis, variance analysis, principal component analysis (PCA), and cluster analysis. 【Result】 There was significant variation in the leaf phenotypic traits among the holly germplasm resources, particularly in leaf area. The Shannon diversity index ranged from 1.00 to 2.03, indicating rich phenotypic diversity primarily due to interspecies variation. Correlation analysis showed a significant negative relationship between external leaf traits and anatomical traits. PCA identified four principal components, namely leaf length, tissue compactness, palisade tissue thickness, and stomatal density, that accounted for 85.20% of the variation, effectively capturing the overall characteristics of the holly plants. Cluster analysis grouped the 42 resources into four categories based on their leaf traits: large leaf with large petiole, small leaf with small petiole, medium leaf with hard serrations, and medium leaf with thin texture. 【Conclusion】 The study confirms substantial intrageneric phenotypic diversity in holly, driven predominantly by interspecies differences. External leaf traits were pivotal in phenotypic differentiation. The identified principal components, namely leaf length, compactness, palisade structure, and stomatal density, are crucial for classifying and identifying holly germplasm resources. Based on the leaf phenotypes, the resources were categorized into four distinct groups, providing a theoretical foundation for further classification, resource utilization, and breeding within the genus Ilex L.

Key words: Ilex(holly), leaf phenotypic, traits variation, cluster analysis