Dynamic Changes Of Pigments Content And QTL Analysis Of The Capsanthin Content Of Pepper

Pepper(Capsicum spp.) ,one of the most important vegetable crops,has abundant nutrition. During fruits ' development, change of fruits 'color is chie?y because of the presence of typical carotenoids and the relative content of specific pigments. Knowledge of dynamic changes of the content for each pigment components during fruit development is very useful for application and academic research. Capsanthin, one important natural pigment, widely used in food, medicine and cosmetic industries, has great potential market. In China, pepper varieties for red pigment extracted most are local cultivars, and few, which restricts the development of pepper pigment extracted industry in China. It is very necessary to carry out breeding work for red pigment extracted and relative basic work.In this study, the content of capsanthin,β-carotene, zeaxanthin, lutein and lycopene of 5 different pepper cultivars were detected during the fruit development to research the dynamic changes of the content for each pigment components. Capsanthin content of 33 different hot and sweet varieties were evaluated on the physiological maturity stage (about 60 days after flowering). The results would be a basis reference for breeding work. To research the genetics of the capsanthin content, a RIL population from Perennial across 83-58 were used for constructing genetic linkage map. Capsanthin content, basides First flower node, plant height, fruit diameter, fruit length and fruit thickness were evaluated in the population and the result were used to do QTL analysis. These results can be useful basis for molecular assisted breeding. The main results in this paper were summarized as follows:1. At the green stage of fruit development,β-carotene and lutein have been detected in all 5 varieties. With the fruit's development, the content ofβ-carotene increased gradually, while the content of lutein decreased. When the fruit get into turning stage (about 40～50 days after flowering), the content ofβ-carotene decreased in all five cultivars except'Qiemen'. Content of lutein decreased rapidly, while lutein content of the other four varieties wtih red mature fruit increased abruptly. At the turning stage, Content of capsanthin, zeaxanthin, and lycopene in fruit of 4 varieties with red mature fruit increased dramatically. Then, at the turning stage, the content of all pigment display a small decline process. In the physical maturity stage, capsanthin,β-carotene, lutein, and lycopene levels were rising rapidly, while the zeaxanthin content was continued to decline. As to the cultivar with yellow mature fruit, content of capsanthin is very low during whole period of fruit development, highest 0.138 mg·kg-1 (fresh weight), and contrary to the other four varieties wtih red mature fruit, content of zeaxanthin in'Talanduo'increased rapidly after fruit get into thephysical maturity stage.2. In order to effectively evaluate capsanthin content of different cultivars, 33 varieties were divided into two groups according to fruit size. The results shows that:Content of capsanthin in 33 pepper varieties is Significant different.capsanthin content of Hongdu and 8819 is much higher than other hot pepper varieties, the Capsanthin content are 218.093mg·kg-1(dry weight) and 195.145 mg·kg-1(dry weight); Zhongjiao 8 and Qiemen has a higher capsanthin content than other sweet pepper cultivars, and the Capsanthin content are 23.827 mg.kg-1(fresh weight)and 21.459 mg·kg-1(fresh weight).so they may be good material resources for breeding.3. A molecular genetic linkage map including 16 linkage groups was conctructed, and it composed of 108 makers, including 99 SSR makers, 7 CAPS makers and two morphological markers (pun and up). The total distance of this map is 517.33cM, average distance between each maker is 4.79cM. Compared with the map published before, 15 linkage groups were corresponded to 10 chromosomes. QTL analysis results: Three capsanthin content related QTL loci were obtained on chromosomes 2,10,12, they accounted 7.6%,8.2%,6.5% of the total phenotypic variance respectively. 10 QTLs for five agronomic traits also detected,including 2 fruit thickness QTLs, 2 fruit diameter associated QTLs, 1 fruit length related QTLs, 2 first flower node related QTL, 3 plant height-related QTLs.