Combining Ability Of RAA Concentration And Screening Of SSR Marker About RAA Concentration-related Gene In Broccoli

Broccoli (Brassica oleracea var. italica Planch.2n=2x=18), originated in the coastal area of Western Europe, was introduced into China from Japan and the United States in the late19th century and early20th century. Because of nourishing and the nutrient content is more plentiful than other vegetables, it is called the queen of vegetable.Glucoraphanin (RAA) is one of the most abundant glucosinoates present in broccoli and its cognate isothiocyanate is sulforaphane(SF), one of the natural plant activity compounds, with the most powerful anti-cancer activity, so far. For a long time, the improvement of variety of domestic vegetables was mainly devoted in increasing yield, but had not enough attention on quality. With the improvement of national living standard, the supplement of production is increasing, at the same time, the number of cancer deaths are rising globally, and the consumer’s health awareness about improving living habit and scientific diet are strengthen, so the quality breeding of vegetable become the focus of society, and broccoli is considered as a very important green and healthy food for its luxuriant RAA.Using6inbred lines of broccoli as parents, combining ability and correlation of primary characters about the RAA concentration and economic characters, such as head weight, were studied by applying Griffing Ⅱ. The inheritance and heterosis of RAA content and economic characters were desk studied. At the same time, searching for related QTL about RAA content in broccoli is contribute to the cloning of related genes about RAA in broccoli, and provides precondition and materials about breeding of new variety and germplasm innovation. It will lay a theoretical foundation for tapping resources and regulatory mechanism of the synthesis of RAA. The main results were as follows:1. Determination and assessment of the RAA concentration and economic charactersApplying Griffing Ⅱ,6inbred lines of broccoli as parents, the RAA concentration was detected and economic characters, such as head weight, head diameter,head height and steam diameter, were studied. The mean content of RAA was2.90μmol/g, with the improving potential about170%; the mean levels and the improving potentials of all economic characters were325.09g and41.19%for head weight,12.58cm and23.18%for head diameter,6.02cm and17.9%for head heigh,4.11cm and28.92%for steam diameter, respectively. There were wide variations of RAA concentration and head weight between types, the type with higher RAA concentration and head weight would be useful in the broccoli breeding works.2. Combining ability of the RAA concentration and economic charactersThe combining ability and genetic parameters were estimated for the RAA concentration and economic characters (such as head weight, head diameter, head height and steam diameter) in F1progenies of15cross combinations of broccoli by using the incomplete diallel cross(Griffing Ⅱ) with6lines as parents. The results showed that the inbred lines P1, P2and P4which had high GCA on the RAA concentration have great value in broccoli breeding with high content of RAA; the inbred lines P2, P3and P5which had. high GCA on the head weight have great value in broccoli yield breeding; The combinations P3XP4, P1×P4and P4×P6had high SCA with better comprehensive characters. The analysis of hereditability revealed that the heredity of RAA concentration, head diameter and steam diameter were mainly controlled by additive effection, while head weight and head height were mainly controlled by non-additive effections.3. The heterosis and correlation analysis of the RAA concentration and economic charactersThe heterosis were estimated for the RAA concentration and economic characters (such as head weight, head diameter, height and steam diameter) in F1progenies of15cross combinations of broccoli, analysis showed that the variation range of mid-parents and better-parents heterosis of the RAA concentration were-0.81～11.91and-0.90～7.88, respectively. And the variation range of mid-parents and better-parents heterosis of head weight were0.20～1.15and-0.12～0.99, respectively. Both of them vary within wide limits and have outstanding performance on the heterosis, so the utilization of heterosis could be used as an effective way in broccoli’s high-quality and high-yield breeding.The results of correlation analysis based on the RAA concentration and economic characters showed that the RAA concentration and head weight had some relativities, their coefficient of phenotypic and genetic correlation were0.0306and0.0569, respectively. But it had not yet to the significant level, which suggested that the selection of two characters could be carried out independently, provided the theoretical basis for broccoli’s high-quality and high-yield breeding. Simultaneously, the positive correlation of main economic characters with head weight was:steam diameter) head height) head diameter, and they also had not yet to the significant level, which suggested that the selection of economic characters could be carried out independently, provided the theoretical basis for broccoli breeding with all eminent characters. 4. Screening of SSR marker linked to RAA concentration-related geneThe F2segregation popuiation, derivated from2broccoli inbred lines with significant RAA concentration, as background to screen the RAA concentration-related gene by using BSA method and SSR molecular marker.4polymorphism markers were screened out,and their coefficient of correlation with the RAA concentration-related gene were reached significant levels.OL10C01and CB10526were located in chromosome4and7of broccoli, respectively. It was useful for cloning the RAA concentration-related gene and provided the theoretical basis for regulatory mechanisms of RAA concentration-related gene.