Analysis of genetic tendency of fruit traits in the reciprocal hybrids of wine grape Chambourcin and Cabernet Sauvignon

Abstract：【Objective】The study aimed to investigate the genetic rules of fruit traits of wine grapes to provide a reference for the rational selection of parent varieties for hybridization and the prediction of representative types after hybridization and improve the competitiveness of China’s wine products. 【Methods】In the experiment, Chambourcin and Cabernet Sauvignon were used as parents, and 105 and 75 individuals with stable flowering and fruiting characters were selected from the reciprocal hybrids respectively. The fruit weight, fruit size, peel thickness, fruit shape, peel color and other fruit traits were investigated and measured. The genetic variation and genetic tendency of fruit traits were analyzed, and the hybrid plants with excellent comprehensive performance were selected by cluster analysis combined with field observation.【Results】The reciprocal F1 hybrids differed significantly in the berry weight, length, width, shape index, skin thickness, and seed number, and the data were close to a normal or skewed normal distribution, exhibited genetic characteristics of quantitative traits. In particular, the mean values of berry mass, berry length and width, berry shape index, berry skin thickness, and seed number in offsprings were all lower than the median values of those of the parents, indicating a genetictendency to low, which might be related to the strong non-additive effect of genes. The coefficient variation of berry weight was about 22.0%, the heterosis rate was -11.96% and -10.53%, and the heritability was 88.04% and 89.47%, respectively. The degree of variation was large, they had high genetic diversity, and the heterosis rate and heritability were low compared with the other traits, which might be easily affected by environmental factors. The coefficient variation of berry width and length ranged from 7.8 to 8.7, which was relatively small, and the heritability was relatively high. The average peel thickness of reciprocal cross was 0.29 mm, which was close to the mid-parent value. The coefficient of variation was 11.37% and 12.64%, respectively, and the heritability was 96.03% and 95.99%, respectively, indicating that it could be stably inherited and was less affected by the environment. The coefficient variation of berry shape index of the reciprocal cross was 3.29% and 3.88%, respectively, which was lower than those of the other traits. The heterosis rate and heritability were higher than those of the other traits, indicating that the fruit shape index could be stably inherited and less affected by the environment. The coefficient variation of the seed number of reciprocal cross was 20.83% and 20.16%, respectively, and the heritability was 92.38% and 93.71% , respectively. The result suggested that the seed number could be stably inherited but the degree of variation be relatively large. The berry weight, width and seed number all showed a genetic tendency towards moderate to low as a whole; the vertical berry diameter and fruit shape index showed a significant tendency to low; the peel thickness showed a significant tendency to moderate; the berry shape, skin color, astringency, and aroma were all similar to the parents, and the flesh texture was heavily biased towards the parent Cabernet Sauvignon, while the flesh color was more influenced by the parent Chambourcin. When Cabernet Sauvignon was used as the female parent and Chambourcin was used as the male parent, the probability of individuals with large fruit and fruit weight was greater than that of orthogonal. By cluster analysis, the orthogonal offsprings could be divided into two categories, the first category included the parent Chambourcin and 32 offsprings, the second category included the parent Cabernet Sauvignon and 73 offsprings; the reverse cross offspring could be divided into three categories, the first category included 32 offsprings, the second category included the father Chambourcin and 4 offsprings, and the third category included the mother Cabernet Sauvignon and 40 offsprings. It was clear that the fruit traits of the reciprocal cross offsprings were greatly affected by the parent Cabernet Sauvignon.【Conclusion】The fruit traits of the reciprocal hybrids of Chambourcin and Cabernet Sauvignon showed a genetic tendency to low and medium as a whole, and through clustering analysis combined with field observation, XC090, XC120, XC215, XC252, CX060, CX07, CX079, and CX090 were selected.