Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 7, 2009
Publication Date: March 15, 2009
Citation: Turley, R.B. 2009. Genetics of Fiber Initiation. National Cotton Council Beltwide Cotton Conference. p. 633 Technical Abstract: To study the cellular mechanisms involved in fiber initiation, three fiberless lines were crossed with wildtype and fuzzless seed cotton and the F1, F2 and BC1 progeny ratios are presently being evaluated. The three fiberless lines included: MD17 (N1N1n2n2), SL1-7-1 (N1N1fl1fl1n3n3) and XZ142w. XZ142w has two genotypes reported in the literature, i.e., n2n2li3li3 and n1n1n2n2li3li3li4li4. With two reported genotypes for XZ142w, the first problem is to determine if either genotype is correct. The populations used in this study were the F1 and F2 progenies of crosses DP5690 X XZ142w and XZFuzz X XZ142w. Both DP5690 and XZFuzz have the same genotype N2N2Li3Li3. The XZ142w genotype n1n1n2n2li3li3li4li4 was dismissed after the F2 populations lacked lintless, fuzzy phenotypes and the Chi square value was out of range for the proposed model. The two loci model was evaluated for the DP5690 X XZ142w cross with all F1 progeny having fuzzy seed which verified that XZ142w was homozygous for the recessive fuzzless seed allele n2n2, and the F2 segregated 361F:100N:31fls (F=fuzzy seed, N=fuzzless seed and fls=fiberless) with a Chi square (12F:3N:1fls) of 2df=0.8266, P=0.66148. For the XZFuzz X XZ142w cross, all F1 progeny had fuzzy seed and the F2 segregated 372F:102N:31fls with a Chi square (12F:3N:1fls) of 2df=0.6950, P=0.70643. These data fit the two loci model very well. In another set of experiments line 143 (n2n2) was crossed with XZ142w. The backcross F1 X 143 was expected to have 100% fuzzless seed in the BC1 population which was validated by all 167 fuzzless seed plants in the population. The expectation that the F1 X XZ142w BC1 population would segregate in a 1N:1fls ratio was confirmed with the observed ratio of 123N:116fls with a Chi square 1df =0.2050, P =0.65070. These data indicate that XZ142w has two recessive loci which interact during ovule development to produce a fiberless ovule.