Relationship between the Dynamic Changes of Phenolic Compounds and the Pigment Synthesis in Cotton Fiber of Natural Brown Cotton

The determining of phenolic compounds dynamic changes and analysis of the relationship between the phenolic compounds metabolism and the synthesis of the pigment in cotton fiber were conducted.Using four kinds of nature brown cotton and one white conventional cotton investigated have been studied from the early elongation stage to the period of secondary wall formation.The qualitative research using ultraviolet-vision spectra and the reagents such as ferric trichloride,sodium hydroxide and 4-aminoantipyrine revealed that the phenolic compounds existed in the fiber of all the four kinds of nature brown and the white cotton before 40 DPA(days post anthesis).The qualitative determination shown the phenolic compounds contents in nature brown cotton fiber were higher than those in white conventional cotton across all the corresponding fiber development stages using the 4-aminoantipyrine method.The phenolic compounds content continually increased in the natural brown cotton fiber and sharply decreased in the white conventional cotton fiber after 40 DPA.The polyphenol oxidase and the peroxydase,which related to phenolic compounds metabolism were also determined. The data indicated that the polyphenol oxidase did not contributed to the phenolics metabolism and the pigment synthesis.The peak at 35 DPA and declining trend of the peroxydase from 35 to 40 DPA had a negative correlation to the brown pigment synthesis.The ferric trichloride test indicated methyl phenol only existed in the natural brown cotton fiber;so we deduced that the methyl phenol was the precursor of the brown pigment.The results will help to analyze the relationship between cotton fiber quality and phenol metabolism in cotton fiber.