Analysis Of The Combining Ability And Preliminary Mapping Of Gene Related To White Immature Fruit Skin Color Of Mini-cucumber In Greenhouse

Mini cucumber is favored by the majority of consumers as a fruit and vegetable varietiy.With the improvement of living standards,the mini cucumber varieties with excellent nutritional quality and appearance quality traits are chased and quickly spread.This research used six mini cucumber inbred lines as parents to build fifteen hybrid combinations according to the second solution configuration of Griffing total diallel crossing.The heterosis of main characters were calculated and analyzed,as well as the combining ability,genetic parameters,correlation and principal component analysis of parents and hybrid combinations were evaluated,which aimed to screen the parents with excellent characters and the hybrid combinations being widely spread and used.It also can provide the theoretical basis for the breeding of mini cucumber.At the same time,six generations population?P₁ ? P₂?F₁?F₂?BCP₁?BCP₂?were made by two mini cucumber inbred lines,whose immature fruit colors had significant differences were dark green?0811?and white?0801?,respectively.It aimed to explore the inheritance regulation and carry out gene primary mapping of immature fruit skin color in mini cucumber.The main results were as follows:1.Variance analysis of agronomic and quality characters The agronomic and quality characters had significant or extremely significant differences in different parents and hybrid combinations.Fruit number at early stage,yield at early stage,carpopodium length,node of the first female flower and soluble protein content showed the maximum genetic variation coefficient,and fruit diameter,photosynthetic rate and fruit water content had the minimum differences in agronomic traits and quality traits.2.Analysis of Heterosis The heterosis of plant characters,single fruit characters,yield characters and quality characters in hybrid combinations were analyzed,and the results showed that it not only improved growth potential,but also can obtained the potential yield and early maturity characteristics in terms of plant characters;It can further reduced fruit shape in terms of single fruit characters;It had no obvious advantage in terms of yield characters;The contents of soluble sugar,soluble solids and dry matter could be increased in terms of quality characters.3.Analysis of combining ability Parent 0815 had excellent comprehensive characters.Number of female flowers per plant,female flower rate and vitamin C content showed highest positive effect value;Plant height showed a higher positive effect value;Fruit number per plant,yield per plant,leaf area of the 15 th node and stem diameter showed a positive effect value.Hybrid combinations 0801×0811 and 0801×0815 had excellent performance in the growth,yield of plant,the maturity and quality of fruit and so on.They had the potential to be promoted and utilized in production.4.Analysis of genetic parameter The broad-sense heritability of node number per plant,leaf area of the 15 th node,node of the first female flower,female flower rate,soluble protein content,fruit water content and fruit hardness were greater than the narrow-sense heritability of them.The selection of these characters is better in later stage of breeding.The narrow-sense heritability of plant height,stem diameter,number of female flowers per plant,fruit number per plant,yield per plant,fruit length,flesh thickness,carpopodium length,fruit shape index and vitamin C were greater than the broad-sense heritability.The selection of these characters is better in early stage of breeding.The effect value of plant height,number of female flowers per plant and carpopodium length in the broad-sense heritability and the narrow-sense heritability were relatively high and had little difference.It was better to choose in early stage.5.Analysis of correlation and principal component The yield per plant showed a significant positive correlation with fruit number per plant,yield per plant at early stage,fruit number per plant at early stage,number of female flowers per plant and female flower rate,and was negatively correlated with the node of the first female flower.The number of female flowers per plant,node of the first female flower,fruit number per plant at early stage,yield per plant at early stage,fruit length,node number per plant,vitamin C,soluble protein content and fruit water content were used as indicators to evaluate the agronomic traits and quality traits of mini cucumber.6.Genetic analysis of immature fruit color character Genetic analysis of immature fruit color character in six generations population was carried out and the results showed that the fruit color of F₁ population was green;In F₂ and BCP₁?P₁× F₁?segregating populations,the separation ratios of the plants with green and white immature fruit skin color were 3:1 and 1:1,respectively.The fruit color of BCP₂?P₂× F₁?population all was green.According to Mendel's law of segregation,the immature fruit skin color of mini cucumber was a quality trait controlled by a single gene,and the white was recessive to green in immature fruit skin color.7.Preliminary mapping of gene related to white immature fruit skin color The results about preliminary mapping of white immature fruit skin color character of mini cucumber through polymorphic molecular markers developed by the method of BSA combined with RNA-seq showed that the target gene controlling the white immature fruit skin color trait was initially located at the position between the 38.73 Mb to 39.70 Mb in the end of chromosome 3,and the physical distance was about 0.97 Mb.