Analysis of the fatty acid composition and genetic relationships of walnut cultivars and elite forms from the gene pool at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine-making to enhance the breeding efficiency for the biological value of fruits

The article presents the results of studying the fatty acid composition of fruits in 23 walnut cultivars and elite forms from the gene pool at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine-making as well as their genetic relationships based on microsatellite genotyping. The total fat and the content of individual polyunsaturated, monounsaturated, and saturated fatty acids in the fruits were determined. Ten microsatellite DNA markers were used to analyze genetic diversity. The total fat content in the fruit kernel (oil content) was found to vary within the range of 67.54–77.85 %. The Rodina cultivar (>75 %) and the elite forms Slavyanin, Shchedry, Saturn, Vengersky, Izyashny, and Konkistador (about 75%) have the highest oil content. In terms of the polyunsaturated fatty acid content in the oil, the cultivar Pelan (79.72 %) and the elite forms Slavyanin (75.59 %), Saturn (75.60 %), Topaz (77.46 %) stand apart. The cultivars Zarya Vostoka (73.97 %), Urozhainy (74.44 %), and Dachny (74.78 %), as well as the elite forms Izyashny (72.29 %), Maslenichny (72.47 %), Yuzhanin (71.80 %), and Vengersky (71.79 %) are also valuable in this respect. The samples Izyashny, Konkistador, Dachny, and Slavyanin have the most optimal Omega-6 (linoleic acid) to Omega-3 (alpha-linolenic acid) ratio (within the range of 3/1–4/1). Genetic diversity analysis determined the average number of alleles per locus to be 6.700, and the average effective number of alleles per locus to be 4.116, which indicates a relatively high level of genetic diversity. According to the results of genetic relationship analysis of the studied sample, two groups with the greatest genetic similarity were identified. These findings are consistent with the origin of the samples. In the identified groups of the strongest genetic similarity, samples possessing both individual economic traits and their complexes were selected. Pairs of samples promising for selective breeding were proposed. The most valuable samples for breeding include Saturn, Pelan, Urozhainy, Zarya Vostoka, and Shchedry (group № 1) as well as Slavyanin, Rodina, Dachny, Izyashny, and Konkistador (group № 2).

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