The Effect Of Fiber Quality And Quantity On ‘B0011’ And ‘Huazamian H318’ With IaaM Gene

Cotton is one of the important economic crops in China. Cotton yield and fiber quality are important indexs to evaluate cotton varieties. Genes involved in cotton high yield and quality could be transferred into the breeding strains through genetic engineering, which is an important means of genetic improvement of yield and fiber quality in cotton.iaaM gene specifically expressed in cotton ovule epidermal can significantly enhance the cotton lint percentage（Zhang et al. 2011）. In this study, iaaM gene was introduced into "B0011"（parent of "Huazamian H318"）, which has good comprehensive properties as the backcross parent, through backcross with the "THL" line as donor parent.A population was obtained after 4 backcross and 1 selfing generation. To evaluate the genome reversion rate of these strains, SSR molecular markers were employed. The result of field investigation in agronomic traits, the improved "B0011" strains with higher lint percentage and lower micronaire were obtained. After selection, molecular characterization and selfing 4 strains were elected for further study. Then, the hybrids were evaluated with these 4 strains as the parents crossing with "4-5", anther parent of "Huazamian H318". The resoults are as follows.1 The detection of the background recovery ratios of the 4 lines（A-26, A-65, A-84 and A-88） in the BC₄F₁ populations. A total of 608 pairs of SSR molecular markers were used to screen polymorphism in "THL" and "B0011". We got 41 pairs of polymorphism markers. The theoretical reversion rate of BC₄F₁ generation was 96.88%. The average genetic background reversion rate of A-26, A-65, A-84 and A-88 were 95.83%, 95.94%, 94.31% and 94.49%. they were 1.05%, 0.94%, 2.57% and 2.39% lower than the theoretical value. The genetic recovery rates of four strains were lower than the theoretical value, one possible reason is that there are some linkage drags in the donor chromosomes, which are difficult to be removed by backcross.2 We got 4 improved strains of the BC₄F₂ generation, which was B-26, B-65, B-84 and B-88. The results of agronomic traits are as follows. The branch number and the boll weight of the 4 strains showed no significant difference. The boll number of B-88 was significantly lower than "B0011". The Lint percentage of B-84 had significantly lower than B0011. The fiber elongation, fiber uniformity inde and the micronaire of the 4 strains were superior to "B0011". Furthermore, the fiber strength and micronaire of B-26 had significantly difference from "B0011". The agronomic traits of the 4 strains are similar to "B0011". But, there is no significantly improvement in lint percentage. For fiber quality, the upper-half mean fiber length, fiber strength and micronaire value of the 4 strains were better than "B0011".3. We indentified the expression of iaaM in ovule in hybrid lines including Z-66, Z-67, Z-68 and Z-69. From the PCR detection, there were null plants（Z66-N） and positive plants（Z66-P） in Z-66. We consider the null plants as contrast. The expression level of iaaM gene in the 4 hybrid lines was that Z-66-P, Z-67 and Z-68 were similarity and higher than Z-69.4. We analysised the yield, agronomic traits and fiber quality of the 4 hybrid lines including Z66-P, Z66-N, Z-67, Z-68 and Z-69. The yields of the 4 hybrid lines were lower than ’Huazamian "H318", The lint percentage of the 4 hybrid lines had significantly difference compare to "H318". The agronomic traits of the 4 hybrid lines were similar to "H318". For fiber quality, Z-67 is better than "H318", the others were similar with "H318". Besides, the lint percentage of Z-66-P was higher than Z-66-N, but there was no significant difference. The micronaire value and fiber strength of Z-66-P was significantly better than Z-66-N.Above all, iaaM gene could improve the lint percentage of ’Huazamian H318, and it could reduce the micronaire value and improve fiber strength.