Study On Genetic Regularity Of Fruit Firmness And QTL Mapping Of Tomato Fruit Firmness

Tomato is a world of fruit and vegetable varieties, which is listed as the 30 kinds of the highest production crops all over the world, the production is second only to potato. The nutritional value of Tomato is very high, has a good effect to prevention of cardiovascular and cerebrovascular disease, prevention of stomach disease, adjust and fight against cancer, slow aging. In the trend of "Southern vegetables transported to north,and north vegetables mobilize to Southern " the large vegetables circulation and mechanized harvest, the fruit firmness of tomato becomes an important factor in tomato harvesting and transportation process affecting the quality of tomato. In the process of harvesting and transportation, the tomato is very easy to loss, which leads to the increase of mold contamination index of tomato products, short storage time, increase the cost and reduce the economic benefit. A good tomato varieties, people not only have certain requirements in fruit appearance, flavor, nutritional value, but also have higher requirements in fruit storage transportation and hardness. There are three ways to solve this problem:(1) Early harvest;(2) Improve the transportation equipment;(3) Plant the storage and transportation of tomato varieties. The first two methods rather than reducing the flavor quality of tomato is the increase in transportation costs in the process of transportation, only a third is economy and the most effective method, which not only keeps the original flavor of the tomato and increase the economic benefit, so the cultivation of tomato varieties with high hardness is particularly important.In this experiment,two kinds of tomato varieties of different hardness 14630 and 14803 were used as parent, a six generations of temporary research group is constructed, and hardness of six generations of fruit and other traits associated with hardness were investigated, Correlation between fruit firmness and other traits and the inheritance of fruit firmness were studied, at the same time, molecular markers were used for constructing genetic linkage maps, and QTL analysis based on the statistics of field characters and genetic linkage map. With a view to lay the foundation of accelerating the selection and selection of high hardness tomato varieties, the identification of the high hardness tomato germplasm resources and identification of varieties which is resistant storage and transportation. The results are as follows:(1) Single fruit weight, transverse diameter and longitudinal diameter, fruit shape index, flesh thick, solid matter, hardness and hard flesh, viscosity traits showed continuous change, show normal distribution, skewness and kurtosis values are less than 1 and close to 0, consistent with typical quantitative genetic characteristics, except the locule number.(2) Flesh hardness, soluble solids, fruit shape index, flesh thickness, longitudinal diameter is positively correlated with the fruit firmness, and Ventricular number, viscosity, diameter, fruit weight is negatively correlated with the fruit firmness. And phenotypic correlation and genetic correlation are basically consistent. In path analysis, the flesh hardness and soluble solids of fruit have a significant positive effect on fruit firmness. Ventricular number, viscosity have a significant positive effect on fruit firmness.(3) The heredity of tomato fruit firmness is consistent with the additive-dominant model controlled by one pair of major genes and additive-dominance-epistasis model controlled by polygene; the additive effect(d), dominant effect(h) and potential ratio(h/d) of major genes were 17.1468, 0.8731 and0.0509, respectively. Additive effect shown positive additive effect and Dominant effect performed partial dominance. the hereditability of major gene effect in BC1, BC2 and F2 generation is 1.64%、1.45% and 0.88%, respectively. The hereditability of polygene gene effect in BC1, BC2 and F2 generation is 26.75%、69.05% and 60.98%, respectively.(4) Using ICIMapping QTL to construct a genetic linkage map. The genetic linkage map contains 3 linkage groups, 19 markers, and the full length is 260.11 cM, the average distance between markers is 13.69 c M.(5) Using QTL Ici Mapping, a total of 21 QTLs were detected by the method of inclusive composite interval mapping(ICIM), including 3 QTLs for fruit weight; 3 QTLs for the transverse diameter; 1 QTLs for the longitudinal diameter; 1 QTLs for the fruit shape index; 2 QTLs for the flesh thickness; 3 QTLs for the soluble solid; 3 QTLs for the soluble solid; 2 QTLs for the fruit firmness; 4 QTLs for the flesh firmness; 2 QTLs for the viscosity.