The Study On Accumulation And Inheritance Of The Pigment In Brown Cotton Fiber

Compared with the white cotton, brown colored cotton has the disadvantage of distability, decomposition and irregulation of pigment accumulation. Therefore, studies on chemical nature, synthesis mechanism and inheritance law of the pigment in brown colored cotton are important basis for brown colored cotton breeding. Cotton bolls from different development stages and mature fiber of brown colored cotton were used as materials in the experiment, and the pigment accumulation also with the activities of phenylalanine ammonia lyase, polyphenol oxidase and antioxidases during the development were analyzed, and inheritance law of the pigment was studied by quantitative determination of the pigment, so as to clear the synthesis path of the pigment, and provide therotical basis for proper breeding methods of brown colored cotton. The main results were as follows:(1) The distribution of the pigment in each part of the fiber of middle-brown ANL-1 revealed the the accumulation and distribution law of the pigment in the fiber of brown colored cotton, and the content of the pigment in each part of the fiber was: the proximal part to the seed capsule(0mm~5mm)>the remote part from the seed capsule(10mm~15mm)>the part close to the seed capsule(5mm~10mm)>the end part of the fiber(15mm~20mm). The content of the pigment in the proximal part to the seed capsule was higher than other parts of the fiber, which can provide the basis for the conclusion that the pigment transported and diffused from the seed capsule to the fiber.(2) The color of the seed capsule of brown colored cotton and white cotton had no apparent changes during the period of the fiber elongation(0~25DPA), and the color of the seed capsule darkened apparently during the secondary cell wall thickening period(25~45DPA).The color of the fiber of brown colored cotton darkened along with the time during the development, which darkened obviously during the secondary cell wall thickening period(35~45DPA).(3) The HPLC qualitative determination results showed that: Catechin monomers in the seed capsule of dark-brown ANL-1 and simiansanhao during the development were epigallocatechin, and epicatechin, and catechin monomers in the fiber of dark-brown ANL-1 and simiansanhao during the development were gallocatechin and catechin. The general change of the content of flavonoids, condensed tannin, all phenol and catechin during the development revealed that: During the period of the fiber elongation (0~25DPA), the precursor of pigment synthesized and accumulated both in the seed capsule and the fiber, and exhausted during the secondary cell wall thickening period(25~45DPA).(4) Phenylalanine ammonia lyase and peroxidase had some influence on the color of the brown colore cotton. The activity of phenylalanine ammonia lyase both in the seed capsule and the fiber of brown colored cotton increased during the 35~42DPA and 21~28DPA, which related to the synthesis of the pigment precursor. During the secondary cell wall thickening period(35~45DPA), peroxidase might participate in the synthesis of the pigment through inhibition of the oxidation of phenols. The influence of polyphenol oxidase, ascorbate peroxidase, superoxide dismutase and catalyse on the color of brown colored cotton were small.(5) The proportion of genetic separation of the pigment in filial generation 2 crossed by dark-brown ANL-1 and simiansanhao was 1:2:1, and the heritability in broad sense was 73â„…. The genetic approach of the color of brown colored cotton fiber was incomplete dominant inheritance. The length of fiber, single boll weight and lint percentage were three important traits in the inheritance of the pigment of brown colored cotton fiber. The trait of fiber length locus and the trait of color locus might be non-allelic located in the same chromosome, which were incomplete genetic linkage.