Polymorphism of the FaOMT and FaFAD1 genes for fruit flavor volatiles in strawberry varieties and wild species from the genetic collection of the Michurin Federal Research Center.

Fruit aroma is an important consumer attribute of strawberry varieties. The key volatile compounds of the aromatic complex of strawberry fruit are mesifurane (fruity and caramel aromas) and γ-decalactone (fruity, sweet, or peachy aroma). The mesifurane content in strawberry fruit is controlled by the FaOMT gene, which is mapped to the distal region of the long arm of chromosome VII-F.1. The γ-decalactone content in strawberry fruit is controlled by the FaFAD1 gene, mapped to the distal region of the long arm of chromosome III-2. Identification of forms carrying genes for fruit flavor volatiles is an important step in breeding varieties with fragrant fruit. The use of molecular markers allows highly reliable detection of target gene alleles in a genome at early developmental stages. This study involves molecular genotyping of Fragaria L. varieties for the FaOMT and FaFAD1 genes, analysis of polymorphism of the loci in question, and identification of genotypes valuable for breeding. The objects of our study were wild species of the genus Fragaria L. and strawberry varieties (Fragaria × ananassa Duch.) of different ecological and geographic origins. To assess the allelic states of the FaOMT gene, the codominant marker FaOMT-SI/NO was used, and for the FaFAD1 gene, the dominant marker FaFAD1. The functional allele of the FaOMT gene (FaOMT+) in the heterozygous state (FaOMT+FaOMT- genotype) was detected in 34.9 % of the accessions tested. The functional allele of the FaOMT gene in the homozygous state (FaOMT+FaOMT+ genotype) was detected in 51.2 % of the accessions. The homozygous state of the inactive allele (FaOMT-FaOMT- genotype) was detected in 13.9 % of the studied strawberry accessions. The FaFAD1 gene was identified in 25.6 % of the analyzed collection of strawberry genotypes, including the wild species F. orientalis Los., F. moschata Duch., F. ovalis Rydb. The combination of functional alleles of the FaOMT and FaFAD1 genes was detected in 16.3 % of the analyzed forms. The wild species F. orientalis Los. and F. moschata Duch. and strawberry variety Red Gauntlet combine the functional allele of the FaFAD1 gene with the homozygous state of the active allele of the FaOMT gene; therefore, we recommend them as promising sources of high contents of mesifurane and γ-decactone in fruit in breeding programs for fruit aroma.

[Nutrient value of fruit in promising strawberry varieties].

One of the current areas in research of fruit and berry crops is the study of their nutritional value and micronutrient composition. Valuable chemical composition of the strawberry determines a wide spectrum of its utilization not only as fresh fruit, but also as a raw material for food industry. Breeding requirements for contemporary strawberry varieties together with yield, large-fruit, important taste and dietary qualities of fruit provide for higher content of biologic active substances. The aim of the research was an integrated assessment of strawberry fruit for content of nutrients and bioactive compounds, as well as mineral elements, and its antioxidant activity. Material and methods. The objects of investigation were berries of 5 strawberry varieties bred in the I.V. Michurin Scientific Centre (Lakomaya, Prazdnichnaya, Privlekatelnaya, Urozhaynaya CGL, Feyerverk) and 9 foreign varieties (Vima Zanta, Dukat, Zefir, Kama, Maryshka, Red Gauntlet, Festivalnaya romashka, Honey, Elsanta) which are promising for cultivation in the Black Soil Region of Russia. The content of soluble solids was determined by the refractometric method, sugars - by Bertrand's method, pectins - by the volumetric method, anthocyanins - by pH-differential spectrophotometry. Total content of antioxidants was defined by amperometric method with recalculation per quercetin. Determination of vitamin B1 was carried out using the fluorometric thiochrome method, vitamin B2 - by fluorometric titration with riboflavin-binding apoprotein after acid-enzymatic hydrolysis, ascorbic acid, vitamin E (tocopherols), niacin, organic and hydroxycinnamic acids - by HPLC, flavonols - spectrophotometrically, minerals and trace elements - by atomic absorption method. Results and discussion. A significant variation in the chemical composition indices depending on the varietal characteristics was found. Strawberry fruit accumulated 8.5-12.0% soluble solids, 5.9-8.7% sugars, 1.5-2.1% of fibre, 0.78-1.12% pectin substances, 0.89-1.45% organic acid; 100 g contain 33.5-48.2 mg vitamin C, 18.3-108.5 mg anthocyanins, 0.024-0.041 mg vitamin B1, 0.012-0.029 mg vitamin B2, 0.10-0.26 mg niacin, 0.26-0.60 mg TE vitamin E, 102-270 mg potassium, 0.15-0.95 mg iron; total antioxidant activity ranged within 180.8-350.0 mg/100 g. High level of anthocyan accumulation (over 80.0 mg/100 g) was observed in Privlekatelnaya, Lakomaya and Feyerverk strawberry varieties. Urozhaynaya CGL, Privlekatelnaya and Lakomaya varieties were characterized by dessert taste. According to the results of the studies Privlekatelnaya variety stood out because of the high complex accumulation of vitamin C, anthocyanins, and high total antioxidant activity. These varieties are recommended for both fresh use and for freezing, as well as for production of functional foods. Conclusion. The obtained data are of interest for further inclusion in the Tables of the chemical composition of Russian food products.