Effect Of Aging On Cotton Fiber Quality

?Object?Cotton(Gossypium hirsutum L.)is the world's main economic crop and it's also the most important source of natural fiber in the textile industry.The quality of cotton directly determines the efficiency of textile enterprises and the quality of fabrics.However,raw cotton is prone to aging problems,such as yellowing and strength reduction during production,processing and storage,which will affect subsequent spinning and sales.Since the quality of cotton fiber largely depends on the genetic characteristics of the variety.Therefore,it is possible to alleviate the problem of fiber yellowing by genetically improving variety traits.This research aims to study the effect of aging on cotton fiber yellowing,strength and other quality characteristics,explore the reasons for cotton fiber yellowing,and explore the possibility of using molecular technology to reduce or even eliminate yellowing.?Methods?In this study,methods such as high temperature,strong light and chemical reagent treatment were used to artificially accelerate the aging of cotton fibers,using HVI1000 Cotton Mass Quality Analyzer to determine fiber quality;analyze the expression of Gh LAR and Gh ANR genes during fiber development of different cotton varieties by real-time fluorescent quantitative PCR;construction Gh LAR,Gh ANR RNAi,and knockout vectors,agrobacterium-mediated genetic transformation of upland cotton "YZ-1" hypocotyl to obtain cotton transgenic lines.?Results?(1)After dry heat treatment of cotton fiber in 60?,75?,90? ovens for 1 h,2 h,3 h,4 h and5 h,the fiber yellowness(+b)value increases with the increase of temperature and time,and the fiber strength value decreases accordingly;during water bath immersion treatment,the fiber yellowness(+b)value did not change at 60?,75?(+b)value increased,90?(+b)value decreased,and the fiber strength value decreased with the increase of temperature and time.After autoclaving the cotton fiber at 105?,120?,135? for 1 h,2 h,3 h,4 h,5 h,it was found that the fiber yellowness(+b)value increased with the increase of temperature and time,and the fiber strength decreases,and the color of the fiber also changes to brown.Soaked in water under the same conditions,the fiber yellowness(+b)value increases with the increase of temperature,and the fiber strength value decreases with the increase of temperature and time.For 10 d,20 d and 30 d of cotton fiber treated with strong sunlight and artificial climate box,the fiber yellowness(+b)value and strength value will decrease with the increase of time.The cotton fiber is soaked in HCl(p H=2)solution and Na OH(p H=12)solution for 6 h,12 h,18 h,24 h,48 h,the yellowness(+b)value and strength value of cotton fiber increase with time.(2)The N-butanol hydrochloric acid experiment proanthocyanidin extraction experiment found that the immature cotton fiber proanthocyanidin extraction solution was red,and the mature cotton fiber proanthocyanidin extraction solution had no color change.Calculating the proanthocyanidin content with the absorbance value of 550 nm found that the proanthocyanidin content of immature cotton fiber was about 3 times that of mature cotton fiber.Through of the 5 DPA,10 DPA,15 DPA,20 DPA,25 DPA proanthocyanidin metabolism pathway key enzymes Gh LAR and Gh ANR genes in 4 cotton varieties including HY171,19-43-58,2004-2,YZ-1,expression analysis found that the expression levels of the two genes in the fibers of YZ-1 varieties were significantly lower than those of the other three varieties.The expression of Gh LAR in the four varieties gradually decreased with fiber development,while Gh ANR showed a trend of first increasing and then decreasing,and the highest expression level at 15 DPA,the expression level is about 70 times that of Gh LAR;in the four varieties,the expression level of Gh ANR is always higher than that of Gh LAR,starting at 20 DPA,the expression level of Gh ANR in HY171 is significantly higher than the other three varieties.(3)Construction of Gh LAR,Gh ANR gene knockout and RNAi interference vectors,and Agrobacterium-mediated transformation of cotton.?Conclusion?Artificial accelerate cotton fiber aging found that aging has a greater impact on fiber yellowness and strength.In a high-temperature environment,when temperature and humidity work together,the degree of yellowing of cotton fiber is more significant;different varieties of Gh LAR,Gh ANR have different gene expression levels,the cultivar HY171 with a higher yellowness coefficient(+b)value has significantly higher expression levels of Gh LAR and Gh ANR in the late fiber development period(25DPA)than other cultivars,it shows that the gene expression levels of Gh LAR and Gh ANR may affect cotton fiber yellowness;Gh LAR and Gh ANR gene knockout and disturbed embryogenic callus were obtained through genetic transformation experiments,in order to further explore the relationship between Gh LAR,Gh ANR genes and cotton fiber yellowness Research has laid the foundation.