Analysis of fruit quality of two interspecific hybrid progenies between Fragaria ananassa Duch. and Fragaria nilgerrensis Schlecht.

Abstract:【Objective】In order to utilize two interspecific hybrid strawberry progenies, contents and compositions of sugars, acids and amino acids, and the correlations between sugar, acid and fruit color were analyzed.【Methods】The progenies of two interspecific hybrids of Fragaria nilgerrensis Schlecht. were used as the materials to determine the fruit color, single fruit weight, total soluble solids and other fruit quality traits. Meanwhile, gas chromatography-mass spectrometry (GC-MS) was used to identify and compare the sugar, acid and amino acid metabolites in the fruit.【Results】(1) Fruit weight of No. 1 was significantly higher than that of No.16, but the content of total soluble solids in No. 16 was 1.15 times that of No.1. The color brightness (L*), yellow index (b*) and hue angle (H) of the peel of No. 1 were significantly higher than that of No. 16, and the E*ab, CCI, a*/b* were significantly lower in No. 1, indicating that No. 1 fruit surface was more shiny, and that No. 16 fruit surface was more reddish. (2) Among the two strawberry strains, 33 sugars were identified, of which xylose was the highest, account- ing for 62.68% and 50.71% of the total sugar content, in No.1 and No.16, respectively, followed by ino- sitol (2.78%, 5.78%) and glucose (0.41%, 0.85%), and the contents of fructose (0.006 1%, 0.010 8%), sucrose (0.013 0%, 0.097%) and galactose (0.075 5%, 0.108 4%) were all low. Fifty three organic acids  were identified and citric acid was the highest, which was 57.42% and 46.61% in No. 1 and No. 16, re- spectively, followed by malic acid (7.65%, 6.35%), succinic acid (0.33%, 0.26%), ascorbate (0.30%, 0.40%), quinic acid (0.11%, 0.10%), lactic acid, salicylic acid, tartaric acid, etc. Twenty-seven amino ac- ids were identified. From high to low, they were oxyproline (5.36%, 4.47%), alanine (1.19%, 2.26%), asparagine (1.15%, 0.62%), aspartic acid (0.26%, 0.17%), serine (0.26%, 0.17%), tryptophan (0.13%, 0.10%), and amino acids in micro amount including isoleucine, cycloleucine, methionine, cysteine, glu- tamic acid amino acid, phenylalanine, etc. The results showed that carbohydrate metabolites in No. 16 fruit was higher than that in No. 1, among which xylose, glucose, fructose, galactose and sucrose were 1.22, 2.09, 1.77, 1.44 and 1.34 times that of No. 16, respectively. The total relative contents of organic acids and amino acids in the fruit were higher in No. 1 than in No. 16. citric acid, malic acid, palmitic acid, stearic acid, oxyproline, asparagine and aspartic acid in No.1 was 1.23, 1.46, 2.28, 1.20, 1.85 and 1.53 times at of No.16, respectively, but alanine in No.16 was 1.90 times that of No. 1. The difference in the metabolites in the mature fruits of the two strains was mainly due to the difference in sugars, indi- cating that sugar may be one of the important reasons that affect the different flavors of the two. (3) Through correlation analysis, it was found that organic acids such as malic acid, citric acid and pyruvic acid, and amino acids such as serine, aspartic acid, methionine, glutamic acid and phenylalanine were positively correlated with maltitol and fructose 6-phosphate, and negatively with such sugars as xylose, glucose and fructose. Organic acids such as lactic acid, salicylic acid, and tartaric acid, and amino acids such as alanine, cycloleucine, and citrulline were inversely related to maltitol and fructose 6-phosphate, but positively correlated to sugar metabolites such as xylose, glucose, and fructose. The soluble solids were extremely significantly positively correlated with E*ab, CCI, a*/b*, but negatively correlated withb*, H, and L*. Metabolites such as xylose, glucose, fructose, lactic acid, salicylic acid, tartaric acid, ala- nine, proline, and citrulline were positively correlated with a*, E*ab, CCI, and a*/b* with most of the correlations being extremely significant levels, but negatively correlated with L*, b*, and H. However, malic acid, citric acid, pyruvic acid, valine, serine, aspartic acid, methionine, glutamic acid and other metabolites were positively correlated with L*, b*, H, and negatively with a*, E*ab, CCI, a*/b*.【Conclusion】It shows that the relations between sugars, organic acids, amino acids and fruit color were close and complex, and the intrinsic quality of the fruit affects the appearance quality to some certain extent. In summary, the fruit of No. 16 is high in sugars and low in acids, and its fruit surface is bright in color and is carmine. The fruit of No. 1 is large, bright, pinkish, and high in amino acids.