Abstract:【Objective】 Chinese plum, as one of the important deciduous fruit trees in China, boasts a rich cultivation history and abundant germplasm. As a native Chinese fruit, it is known for its beauty, fragrance, juiciness, and nutritional richness. Chinese plums have played a crucial role in rural revitalization, agricultural structural adjustment, cultivation model upgrades, and the development of fruit orchard industries in various regions of China. China has placed significant emphasis on germplasm innovation and the breeding of new plum varieties to expedite the breeding process. However, the effective utilization of excellent genetic resources is contingent upon precise evaluations of germplasm. To further explore the genetic diversity of taste in Chinese plum and unearth excellent taste germplasm, this study focused on different types of Chinese plum germplasm, including their geographic origins, flesh colors, and sensory taste perceptions. We implemented nine taste parameters with an electronic tongue, including freshness, saltiness, sourness, bitterness, astringency, sweetness, bitter aftertaste, astringent aftertaste, and richness, to conduct precise quantitative assessments and comparative group studies. The objective patterns of taste quality genetics in Chinese plum germplasm were unveiled. 【 Methods 】 The test materials of 50 mature plum fruits were carefully harvested from National Plum and Apricot Germplasm Repository during the ripe season in July to August in 2022 and 2023. For the analysis, 50 g per fruit collected from one or multiple samples was mixed with 150 mL of deionized water in a test tube and shaken at 3000 rpm/min for 5minutes. It used the electronic tongue instrument, which is SA-402B taste analysis system, to accurately identify the taste richness of Chinese plums using six artificial lipid membrane sensors and three reference electrodes. It repeat the sweetness test 5 times for each sample solution, and repeat the other taste tests 4 times. After the measurement is completed, take the average of the last three data as the test result. The potential values obtained from nine taste tests are converted into the final data through the analysis software provided by the electronic tongue. In the data analysis phase, we used multiple analysis packages from R language, including factoextra, cluster, FactoMineR, ggplot2, ggcorrplot and ggrepel. 【Results】 By investigating the taste characteristics of 50 Chinese plum germplasm, including variety origin, flesh color, and sensory taste, we found that plum varieties from different ecological origins exhibited some differences in taste characteristics but were challenging to differentiate overall. Conversely, there was a correlation between flesh color and taste perception, with different flesh colors showing distinct distribution patterns in taste characteristics. The aftertaste-A exhibit a relatively scattered distribution in orange yellow flesh and yellow flesh, while a dispersed distribution of acidity, sweetness, and freshness in the red flesh. The faint yellow flesh is relatively concentrated in the taste sense of freshness and bitterness. The description of acidity/sweetness also reflects a certain relationship with taste sense. Sourness exhibited a higher median in the freshness taste parameter, while sweetness had a higher median in the sweetness taste parameter. The high correlation between sourness and sweetness suggests that these tastes often coexist in certain plums. Based on cluster analysis, it can be divided into six groups. There were analysis conducted on the second, the third, and the sixth groups, which includes box diagram analysis and principal component analysis. In the umami, and sweetness, the distribution of cluster2 cluster3 and cluster6 is similar and discrete relatively, while cluster6 has higher values in the umami and sweetness than the other two groups. In PCA analysis, it can be seen that cluster2 is mainly distributed in the second quadrant, cluster3 is mainly distributed in the fourth quadrant, and cluster6 is mainly distributed in the second and third quadrant. In this study, taste specific germplasm resources were objectively screened. 'Sanhuali' has the lowest sourness taste and also has the highest sweetness value, with outstanding umami value. On the contrary, 'Changlidazili' shows the maximum value of sourness and the minimum value of sweetness in taste, while 'Qiuwangli', 'Zhengzhouzaoli', and 'Zhenzhuli' have prominent saltness taste characteristics, while 'Hongbaoshi' has the maximum bitterness taste characteristics and is accompanied by a large astringency taste value, ‘ Jinxiqiyueli 'also showed the highest value in bitterness and aftertaste-A, while' Qingzhouli' and' Jinxipingdingxiangli' showed a high degree of taste diversity. 【Conclusion】 Chinese plums can be categorized into sour and astringent type, salty and tangy type, fresh and sweet type. This study also identified a range of germplasm materials with outstanding taste attributes and others lacking in certain taste qualities. These plums, along with their underlying genetic genes, will serve as the 'genetic toolkit' for plum breeding activities in China. These findings provide a scientific basis for plum variety identification and classification, and are of significant importance for plum quality improvement, geographic distribution, and ecological adaptation. This research contributes to the scientific support for the development of the Chinese plum industry.
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