Nuclear DNA content and ploidy levels of living apple germplasm collection in Türkiye

Authors: EMEL KAÇAL, YAREN İPEK ŞİMŞEK, TURGAY SEYMEN, ŞERİF ÖZONGUN, METİN TUNA

Abstract: One of the key uses of flow cytometry is the estimation of nuclear DNA content and ploidy level, which has proven a reliable and effective approach in many studies. The primary goal of this research is to estimate the nuclear DNA content and ploidy level of the apple genetic resource collection maintained in the Fruit Research Institute?s living Malus collection for the first time using flow cytometry (for autochthonous varieties). Fresh apple leaf tissues were used for the flow cytometry analysis. For each genotype, nuclear DNA analysis was performed on three individual plants. Propidium iodide (PI) is used as a fluorochrome. Common vetch (3.65 pg/2C) was used as an internal standard. The 2C nuclear DNA content ranged from 1.46 pg to 2.45 pg. The variation in nuclear DNA content within the collection was statistically significant. Apple genotypes were split into two groups, diploid and triploid, according to their nuclear DNA content. Based on these results, 16.47% of apple genotypes were triploid, while 83.53% were diploid. The 2C nuclear DNA content in triploid genotypes varied from 2.04 to 2.45 pg and in diploids from 1.46 to 1.69 pg. The average nuclear DNA content in diploids was 1.56 pg, whereas it was 2.29 pg in triploids. The results of the study will be useful to determine the best strategies in breeding programs, as ploidy is one of the most important characteristics to consider in selecting parents for breeding purposes in addition to their agronomic characteristics.

Keywords: Malus x domestica, genetic resources, chromosome number, flow cytometry, nuclear DNA content, ploidy

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