Determination genetic diversity and regional adaptations to climate change of chestnut (Castanea sativa mill.) populations in Türkiye

Türkiye ranks third in the world in terms of chestnut production. However, the increase in environmental stresses due to global climate change has led to a decrease in chestnut production. This study aims to contribute to conservation genetics and breeding studies by investigating the genetic diversity and potential differences in drought tolerance of naturally growing chestnut populations in Turkey. In this context, the genetic diversity levels of 180 Castanea sativa genotypes collected from natural chestnut forests of seven provinces of four geographical regions of Turkey (Düzce, Trabzon, Ordu, Kütahya, İzmir, Antalya, Bursa) were determined by two different molecular marker systems, ISSR and SCoT. In addition, changes in physiological (chlorophyll concentration, stomatal conductance, transpiration, net photosynthesis, intrinsic water use efficiency and xylem water potential) and biochemical (proline content) parameters of chestnut seedlings of six populations (Düzce, Bursa, Deli Sarnıç, Selge, Ovacık, Ibradı), which were subjected to drought stress for twenty- eight days in greenhouse environment, were determined to determine regional adaptations to climate change. Molecular data (total number of loci, number of polymorphic loci, polymorphism information content and genetic diversity) showed that SCoT markers are more advantageous in determining genetic relationships among C. sativa populations. In addition, it was determined that the genetic diversity of Düze population was higher. On the other hand, physiological and biochemical measurements showed that the southern populations (Ibradı, Deli Sarnıç and Selge) were generally drought tolerant and the Bursa population was drought sensitive. In addition, it was determined that the Düzce population also developed drought tolerance. In the light of the findings obtained from molecular, physiological and biochemical data, the higher drought tolerance level of Düzce population was due to its higher genetic diversity. In this context, it can be said that Düzce population has developed adaptation to drought. As a result, Düzce population can be recommended for conservation genetics and breeding studies.