A series of fiber-specific mutants, or germplasms, have been recently used in the study of fiber development. In the current study, scanning electron microscopy （SEM） was used to investigate developmental differences in lint and fuzz initiation in different genotypes （Gossypium hirsutum） of upland cotton. These fiber mutants included dominant naked seed N1, recessive naked seed n2, Xuzhou-142 lintless-fuzzless （XZ142WX）, Xinxiangxiaojilintless-fuzzless （XinWX）, Xinxiangxiaojilinted-fuzzless （XinFLM）, with TM-1, the cytogenetic and genetic experimental standard stock, as the control. Characteristics of fiber initiation were analyzed from -1 to ＋1 days post anthesis （dpa） and at 4 and 5 dpa for fuzz initiation. Our data suggested that lint initiation centered on day of anthesis （0dpa）, and elongated significantly at 1dpa, while fuzz initiation began at 4dpa, although the shape of fuzz protrusions differed from that of lint fibers. Fiber initiation occurred first on the ovule funicular crest. Compared to TM-1, there was a noted retardation in development and fiber protrusion in N1 and XinFLM. Microscopy data also demonstrated that lintless-fuzzless mutants （XZ142WX and XinWX） developed irregular protrusions during early developmental stages, which were unable to grow into fiber.
Da-Yong Zhang Tian-Zhen Zhang, Zhi-Qin Sang Wang-Zhen Guo
Cotton fiber is one of known natural resources comprising the highest purity cellulose. It plays an important role worldwide in the textile industry. With the acceleration of spinning speeds and the improvement of the peoples liv-ing level, the demand of improving cotton fiber qualities is getting stronger and stronger. So, making clear the develop-mental model of fiber cell and elucidating systematically the molecular mechanisms of cotton fiber development and regulation will produce a great significance to make full use of cotton gene resources, raise cotton yield and improve fiber quality, and even develop man-made fiber. In the paper, the status of the gene cloning and the molecular breeding to im-prove cotton fiber quality were reviewed, the importance and potential of gene cloning related with cotton fiber quality were put forward and the proposal and prospect on fiber quality improvement were made. Using national resources available and through the creative exploration in corre-sponding research, some international leading patents in genes or markers linked with cotton fiber development hav-ing Chinese own intellectual property should be licensed quickly. And they can be used to improve cotton fiber quality in cotton breeding practice.
GUO Wangzhen, SUN Jing & ZHANG Tianzhen National Key Laboratory of Crop Genetics & Germplasm Enhancement, Cotton Research Institute, Nanjing Agricultural University, Nanjing 210095, China Correspondence should be addressed to Guo Wangzhen (e-mail: cotton @njan.edu.cn)
Verticillium wilt is a destructive disease with international consequences for cotton production. Breeding broad-spectrum resistant cultivars is considered to be one of the most effective means for reducing crop losses. A resistant cotton cultivar,60182,was crossed with a susceptible cultivar,Jun-mian 1,to identify markers for Verticillium resistance genes and validate the mode of its inheritance. Genetic segregation analysis for Verticillium wilt resistance was evaluated based upon infected leaf percentage in the seedling stage using major gene-polygene mixed inheritance models and joint analysis of P1,P2,F1,B1,B2 and F2 populations obtained from the cultivar cross. We found that resistance of upland cotton cultivar 60182 to isolates BP2,VD8 and T9,and their isoconcentration mixture was controlled by two major genes with additive-dominance-epistatic effects,and the inheritance of the major gene was dominant. Furthermore,a genetic linkage map was constructed using F2 segregating population and resistance phenotypic data were obtained using F2:3 families inoculated with different isolates and detected in different developmental stages. The genetic linkage map with 139 loci was comprised of 31 linkage groups covering 1165 cM,with an average distance of 8.38 cM between two markers,or 25.89% of the cotton genome length. From 60182,we found 4 QTL on chromosome D7 and 4 QTL on D9 for BP2,5 QTL on D7 and 9 QTL on D9 for VD8,4 QTL on D7 and 5 QTL on D9 for T9 and 3 QTL on D7 and 7 QTL on D7 for mixed pathogens. The QTL mapping results revealed that QTL clusters with high contribution rates were screened simultaneously on chromosomes D9 and D7 by multiple interval mapping (CIM),whether from resistance phenotypic data from different developmental stages or for different isolates. The result is consistent with the genetic model of two major genes in 60182 and suggests broad-spectrum resistance to both defoliating isolates of V. dahliae and nondefoliating isolates. The markers associated with resistance QTL may facilitate th
JIANG Feng,ZHAO Jun,ZHOU Lei,GUO WangZhen & ZHANG TianZhen National Key Laboratory of Crop Genetics & Germplasm Enhancement,Cotton Research Institute,Nanjing Agricultural University,Nanjing 210095,China
