Genetic variability in almond (Prunus dulcis L.) in South Türkiye: morphological, biochemical, and SSR analyses

Almond (Prunus dulcis) is one of the most important nut crops cultivated worldwide, valued for its nutritional content and economic significance. Local landraces, particularly those from ecologically diverse regions, harbor valuable genetic variation that can be exploited in breeding programs. This study aimed to assess the morphological, biochemical, and molecular diversity of local almond genotypes collected from a natural population located along the Türkiye-Syria border.

Eighteen promising genotypes were evaluated using morphometric traits, biochemical composition, and SSR markers. Nut weight ranged from 1.50 g to 2.18 g, kernel weight from 0.59 g to 1.50 g, and kernel ratio from 16.43 to 54.99%, indicating considerable phenotypic variation. Genotype G11 stood out with a high kernel weight (> 1.2 g), soft shell, and the highest kernel ratio (54.99%). Oil content varied across genotypes, with G2 having the highest (56.25%) and G15 the lowest (45.85%), and an overall average of 51.50%. Molecular analysis using 16 SSR markers revealed a high polymorphism rate (99.4%), reflecting substantial genetic variability. Principal coordinate analysis (PCoA) and UPGMA clustering distinguished genetically diverse individuals, while STRUCTURE analysis grouped the genotypes into two main genetic clusters.

The high morphological, biochemical, and molecular diversity observed in this almond population highlights the importance of the conservation of local genetic resources. Genotypes such as G11 and G2 show strong potential for use in breeding programs due to their favorable nut quality and oil content. Future work will focus on field evaluations of these genotypes under standard cultivation to assess their agronomic performance.