Identification by SRAP and genetic tendency analysis of fruit characteristics of hybrids in guava

【Objective】Guava (Psidium guava L.) is a perennial fruit tree. Identification of authentic F1 hybrids and verification of genetic tendency of hybrid population is important for enhancing breeding efficiency in guava.【Methods】104 seedlings derived from a cross between Hongxiang No. 1 and Emperor were used as materials, SRAP markers were used to identify the authenticity of the hybrids. UPGMA clustering method was used to calculate genetic distance using NTSYS-pc 2.10, and cluster analysis was conducted. And the quantitative traits [single fruit quality, fruit longitudinal diameter, transverse diameter, fruit shape index, fruit core diameter, fruit flesh thickness, fruit titratable acid (TA) content and soluble solids (TSS) content] and quality traits (fruit shape, fruit surface texture, fruit skin color, fruit flesh color, fruit flesh texture, and fruit aroma) of mature fruits of the two parent varieties and F1 individuals were measured, and the genetic diversity, genetic relationships, and genetic tendencies of fruit characteristics of the F1 individuals were analyzed.【Results】102 true hybrid plants were identified through SRAP markers, and the true hybrid rate was 98.08%. The clustering analysis showed that at agenetic similarity coefficient of 0.90, the parental and 102 hybrid plants could be divided into 6 categories. The F1 hybrids showed a typical normal distribution of the eight quantitative traits, including the single fruit weight, fruit longitudinal diameter, transverse diameter, fruit shape index, fruit core diameter, fruit flesh thickness, fruit TA content, and TSS content, which should be controlled by the multiple genes. The genetic trend of increasing variation in the single fruit weight, fruit longitudinal diameter, transverse diameter, fruit shape index, and TSS content in F1 generation was evident, with obvious hetrobeltiosis. The TA content in the fruit showed a genetic trend of decreasing variation, while the diameter of the fruit core and the thickness of the fruit flesh showed a genetic trend of decreasing variation. The six quality traits of the fruits in the F1 population, including the fruit shape, fruit surface texture, fruit skin color, fruit flesh color, fruit flesh texture and fruit aroma, showed a significant segregation in the F1 generation, with a large degree of dispersion and a high diversity index. The dispersion characteristics and genetic diversity levels of different fruit quality traits varied, indicating that the six quality traits were controlled by different genes. Among them, fruit shape, fruit surface texture, fruit skin color, and fruit flesh color were greatly influenced by the male parent, while fruit flesh texture and fruit aroma were mainly influenced by the female parent.【Conclusion】The SRAP markers was successfully used to identify the true hybrids in guava. At a genetic similarity coefficient of 0.90, the parent varieties and 102 true hybrid plants were divided into 6 categories. The eight quantitative traits of pomegranate, including the single fruit weight, fruit longitudinal diameter, transverse diameter, and fruit shape index, have significant hetrobeltiosis, indicating that the inheritance of the fruit size in guava would be influenced by additive effects. Among the six quality traits, the fruit shape, surface texture, skin color, and flesh color might be greatly influenced by the male parent, while flesh texture and fruit aroma might be mainly influenced by the female parent.