Abstract: The discovery and identification of the fiber mutant has been vital for genetic and functional genomic research in cotton. In this study, we found a linted-fuzzless fiber mutant in transgenic cotton by Agrobacterium-mediated transformation path, the pure line of the mutant was obtained in T₃ generation. We named the novel fiber mutant as CM mutant. PCR analysis showed that the mutation trait had no relationship with T-DNA insertion, but was deduced to be caused by point mutation in the process of tissue culture. Analysis of inheritance and allelic tests were conducted by crossing CM mutant with TM-1, Junhai1, and a series of fiber developmental mutants such as XinFLM, N1N1, n2n2, and T586 with linted-fuzzless fiber and XinWX, XZ142WX, SL-7-1, and MD17 with lintless-fuzzless fiber, respectively. Of above 10 combinations, the F₁ were fuzzless, and F₂ generations of CM×TM-1 and CM×Junhai1, all showed the separation ratio of 3:1 of linted-fuzzless to linted-fuzzed phenotypes. Based on the genetic analysis, we indicated that there was one dominantly different locus between the mutant and TM-1or Junhai1. Allelic tests and gene mapping all showed that the fuzzless gene of the mutant was allelic to N1, dominantly controlling naked-seed trait. Scanning electron microscopy (SEM) analysis was conducted to investigate the development of fiber cell initials in CM mutant during early developmental stages (0–3 DPA). Just like N1N1 mutant, the mutation gene could result in the process of fiber cell formation and elongation delayed. Compared to N1N1, the lint percentage of CM was significantly higher and 100-seed weight was significantly lower. In conclusion, we speculate on that the mutation gene in CM is one of multiple allele genes of dominant naked-seed N1, and the result also shows the mutation reproducibility for fiber development in different cotton materials.

Key words: Gossypium hirsutum L., Transgenic analysis, Fiber developmental mutant, Identification