Metabolic Profiling Of The Major Fruit Quality Components During The Development Of Fragaria×Ananassa 'Fengxiang' Fruits

Fruit flavor are deeply influenced by the contents of sugar and organic acid, as well as the ratio of sugar to acid, and other components related to the metabolism of sugar and acid, such as anthocyanin, amino acid, aroma, also play a crucial role in the formation of fruit quality. The application of metabolomics in the research of fruit quality, is helpful for not only revealing the mechanism of formation, transformation and relationship of the major characteristic quality components in fruits such as sugar, organic acid, amino acid, anthocyanin, aroma and so on, but also for supplying the clue for fruit breeding and quality improvement using modern biotechnique methods.Strawberry (Fragaria ananassa Duch.) as one of perennial fruit trees, has small genome and short reproductive cycle (about 4 months). The characteristic of small plant is suitable for protected cultivation, furthermore, photosynthetic product accumulates in strawberry fruits just in the form of sugar, which is helpful for investigating sugar metabolism because of no disturbance of starch. So, strawberry is a suitable material for metabolomic research to investigate metabolic profiling of the major fruit quality components.Fragaria×ananassa'Fengxiang'fruits serve as the research system in this paper, and the metabolic profiling platform based on the fundmental techniques and methods involved in sample preparation, sample detection and data perform were implored, and that was further applied for the metabolic profiling analysis on the major quality components contained sugar, organic acid, anthocyanin, amino acid and aromatic substances during the development of strawberry fruits, which can help to reveal the complex physiological and biochemical metabolism of quality formation. The main results are as following:The major components of amino acids in strawberry fruits were serine, arginine, glutamic acid, histidine, aspartic acid and proline. During the development of strawberry fruits, the total content of amino acids decreased gradually, from 48.39μg. g-1 in immature stage to 8.62μg. g-1 in mature stage. The major components of amino acids with higher contents differed significantly such as serine, arginine and histidine, and the amino acids with lower contents often gave small decrease.There were few varieties of anthocyanins in strawberry fruits and the major anthocyanin components were Cy3glc and Pg3glc. Pn3glc and Mv3glc were discovered only at start-red stage and 1.37 percent of the whole anthocyanin content. The anthocyanin content increased gradually during fruit ripening. Few anthocyanins were detected in young fruits, but accumulated rapidly during fruit developing. Pg3glc was the major anthocyanin component and accumulated gradually at full-red stage, while the Cy3glc content decreased rapidly from 0.1013 mg.g^-1 at start-red stage to 0.0512 mg.g^-1 at full-red stage.In this experiment, GC and GC-MS methods was well constructed for the identification of organic phase extract from strawberry fruit. The results showed that the sample could be well separated, and 195 peaks were detected and 128 compounds were identified. Esters were the major aromatic components, and terpenoids such as Nerolido and N-hentriacontanolhen-1 played an important role in flavor formation. Based on PCA and PLS analysis, petroleum ether extract from strawberry fruits of the fourth period (sample collected at April 10) was quite different from other growth periods. Cyclohexane extract of the seventh period (sample collected at April 25) was also different from other growth periods.The effects of different derivatisation methods were compared in this paper, and simultaneous derivatisation of sugar, organic acid and alditol can be achived with the derivatisation solvent of BSTFA and TMCS (99:1, v/v). The derivatisation conditions were further optimized by orthogonal experimental design, and treatment no.17 was selected as the optimal derivatisation condition, which is 100μL of 25mg.mL^-1 hydroxylamine hydrochloride, 100μL of 4mg.mL^-1 sugar solution, treated at 40℃for 50min and further added 60μL of BSTFA and TMCS (99: 1) derivatized at room temperature for 40min.The contents of fructose, glucose, total sugar increased gradually during fruit ripening, while the contents of fructose and glucose were low. Organic acid was the major acid component in strawberry fruits, and the content of citric acid was high up to 60 percent. Organic acid accumulated at early stage,and the maximum content was achived at April 10(half-red stage). Organic acid decreased after half-red stage which might be related to the transformation to carbohydrates or oxidization to esters.