# Genetic Diversity of the Only Natural Population of Corylus avellana L. in Kazakhstan and Prospects for Its In Vitro Conservation

## TL;DR

This study examines the genetic diversity of the rare wild hazel population in Kazakhstan and proposes in vitro conservation to protect it.

## Contribution

The study provides the first detailed genetic and morphological characterization of the only wild hazel population in Kazakhstan and demonstrates successful in vitro conservation methods.

## Key findings

- The wild hazel population in Kazakhstan shows high genetic diversity with 120 alleles detected across ten SSR markers.
- The population is genetically distinct from cultivated varieties, as shown by STRUCTURE, PCoA, and phylogenetic analyses.
- An in vitro conservation method using a two-step disinfection protocol successfully preserved the population due to low seed viability.

## Abstract

Corylus avellana L., known in Europe as the common hazel, is extremely rare in Kazakhstan and listed as an endangered species. In this study, morphological characterization of the trees and leaves was carried out, as well as an analysis of their genetic background, to understand the population’s status and conservation prospects. The findings revealed that this group of shrubs has a high level of diversity, which will be highly valuable for future breeding programs. At the same time, the Kazakhstan population differs significantly from cultivated varieties. During the analysis, it was observed that the population is declining and not producing enough viable seeds. Therefore, young shoots were used to preserve the plants in laboratory conditions. This approach enabled the creation of a healthy collection that can be used to restore and protect the species. Our results highlight the need for urgent measures to conserve hazelnut in Kazakhstan and show that modern technologies can play a key role in preserving rare plants for future generations.

Corylus avellana L. is a rare and endangered species in Kazakhstan, included in the national Red Book. The results of morphological and genetic characterization of the sole known natural population of C. avellana in the Western Kazakhstan region are presented in this study. Sixty wild accessions were evaluated based on tree and leaf morphological traits using standard descriptors in accordance with Bioversity International guidelines. Genetic diversity was assessed using ten nuclear simple sequence repeat (SSR) markers. A total of 120 alleles were detected across the nuclear loci, with the number of alleles per locus ranging from 9 to 16 and an average of 12. The mean effective number of alleles (Ne) per locus was 3.862. A high level of intraspecific polymorphism was observed, with an average observed heterozygosity (Ho) of 0.70. The population showed considerable genetic diversity, as highlighted by a mean Shannon’s diversity index of 1.526. STRUCTURE, PCoA, and phylogenetic analyses confirmed strong differentiation between the wild Kazakh population and the cultivated hazelnut germplasm. Due to the lack of viable seeds, in vitro conservation was initiated using vegetative shoots. A two-step disinfection protocol, involving Plant Preservative Mixture and mercuric chloride, significantly improved explant survival, enabling successful establishment of an aseptic in vitro collection. These findings highlight the urgent need for targeted conservation strategies and show the potential of biotechnological approaches for safeguarding Kazakhstan’s only natural C. avellana population.