Synthesis Mechanism Of The Pigment In Naturally Colored Brown Cotton Fiber And Its SRAP Molecular Marker

The main aim of our study was to research chemical structure,synthetic location and the SRAP molecular marker of the pigment in naturally colored brown cotton fiber.Also the relationships between the pigment synthesis and the cotton fiber development were analyzed.The experiments would contribute to breeding of naturally colored cotton.Solubility and purifying methods of the pigment in naturally colored brown cotton fiber were researched at first,such as the recrystallization method,lead salt/cupric salt method,paper chromatography method and silica gel column chromatography method.A efficient technological process for purifying the pigment was designed,and pureness of the pigment was verified by the thin layer chromatography.The pigment was deduced as quinone from condensed tannin oxidation according to the chemical characteristics,the wave spectra of the pigment and physiological measurements.The pigment distribution regulation on the naturally colored brown cotton fiber,the pigment contents and the dynamic contents of condensed tannin in the cotton fiber or coat seeds were analyzed.The results indicated(1)the pigment contents in coat seeds cells were higher than that of cotton fiber;(2)the time of coat seeds appearing color earlier than that of cotton fiber;(3)the color of coat seeds cells which did not develop to cotton fiber were dark brown too;(4)the color of naturally colored brown cotton fiber was dependent on the ratios of pigment between the cotton fiber and coat seeds cell;(5)the darkest color of the naturally colored brown cotton fiber was near the coat seeds cells;(6)condensed tannin contents in the coat seeds cells were higher than that of cotton fiber;(7)dynamic tendencies of condensed tannin contents in naturally colored brown cotton fiber were conform to that coat seeds during 5-30 DPA,but conventional white cotton had not the property;(8)the pigment in the coat seeds cells was same as the pigment in naturally colored brown cotton fiber;(9)the displaying color speed of the naturally colored brown cotton fiber was fastest at the opening boll stage,while metabolism vitality of the fiber was decreased gradually; (10)the pigment distribution regulation on the naturally colored brown cotton fiber did not support the hypothesis that the pigment was convey to the fiber of naturally colored brown cotton after 25 DPA;(11)the color of naturally colored cotton fiber was same as that of coat seeds,such as coat seeds color of nature brown cotton was brown,and coat seeds color of nature green cotton was green.So we got a conclusion that synthesis location of the pigment in naturally colored cotton fiber was in the coat seeds cells.The results also indicated(1)the condensed tannin of naturally colored brown cotton fiber or coat seeds were higher than that of conventional white cotton,and the more pigment contents in naturally colored cotton fiber,the more condensed tannin contents in naturally colored brown cotton fiber or coat seeds during fiber every development stages;(2) triturating liquid of the naturally colored brown cotton fiber blended with 1%FeCl₃(g/g) presented blue-green color,the phenomenon was due to higher concentration of the condensed tannin in naturally colored brown cotton fiber;(3)the more the pigment content in naturally colored brown fiber,the more the efficiency of the pigment conveying to fiber from coat seeds during 5-30 DPA;(4)the pigment contents in the mature cotton fiber had significant correlation with the contents of condensed tannin in colored cotton fiber during 20-25 DPA and the mean contents of the condensed tannin(p＜0.01).we claimed the condensed tannin was the precursor of the pigment in naturally colored cotton fiber according to the characteristics and the chemical properties.The biochemical composition in the 4 kinds of natural brown cotton fiber has been determined from the early stages of elongation to the period of secondary wall formation, comparing with normal cotton Simian-3.The measurement revealed that the moisture content at 40 DPA and the reductive sugar at 10 DPA of normal cotton were higher than that of natural brown cotton,but the reductive sugar of the brown cotton fiber from 30 to 40 DPA showed opposite trend.In contrast to the extractable protein peak of white cotton fiber at 20 DPA,the peak of nature brown cotton fiber arisen at 25 DPA.The cellulose contents of normal cotton at every stage during fiber development were higher than natural brown cotton.The pigment content to the amounts of reductive sugar at 10 DPA and cellulose at 30- 40 DPA was negative correlation significantly at the 0.05 level,and to the 35 DPA reductive sugars content positive correlation significantly at the 0.01 level,to the cellulose content at 15 DPA negative correlations significantly at the 0.01 level.5 kinds DNA extraction methods were compared,and the tests indicated pre-removed method improved the quality of DNA evidently.The result of SRAP-PCR optimization was 25 m mol/L Mg²⁺2.0μl,10 m mol/L dNTPs 0.5μl,template DNA 60 ng,5U/ml TaqDNA polymerase 0.2μl,10 mmol/L primer 1.5μl in 25 ml reaction system.According to SRAP molecular marker,10 cotton cultivars divided into 4 kinds at Jaccard similar coefficient 0.88 level.The bolls development characteristics of naturally colored cotton were studied in comparison with Simian3.The results showed the bolls development characteristics of nature green cotton were obviously different from the characteristics of the white cotton, while nature brown cotton were closed to the white cotton.The length,the maximum width, the volume of a single boll and the length of a single seed,have the liner relationship to the boll age during 0-10 days,and get the maximum at the 15th of boll age.The fiber lengths, the dry weight of a single boll continue to increase after the 15th of boll age.The heredity regulation of the pigment in the naturally colored brown cotton fiber was analyzed on the base of filial generation phenotype.According to eyeballing,the phenotype of self cross F₂ generation could be divided into three kinds.The three kinds were dark brown,middle brown and white.The number of dark brown was 62,middle brown was 121,and the white was 78.The ratio of the self cross F₂ generation was in accord with 1:2:1 by Chi-Square Test(p＞0.05).The contents of the pigment in parent strains and filial generation cotton fiber were measured.The measurement showed the three genetic traits of F₂ generation were discontinuous distribution.So we claimed genetic traits of brown were incomplete dominant inheritance.