A Novel Allele of Li-2 Producing Different Types of Fibers in Cotton Seeds in Different Branches of the Same Plant.

Li-2 is a monogenic, dominant mutant, is characterized by only short fuzz fibers on mature seeds in cotton.  We observed an abnormal phenotypes associated with Li-2  where individual plant with branches producing different types of fibers in the same plant.  We used Li-2 in partial diallel crosses with FM 966 (normal seeds with both lint and fuzz fibers), MD17 (an USA fiberless line), 177 (another Chinese fiberless line), and 181 (naked seed with only lint fiber line). We did not observe the abnormal phenotypes among the crosses with any other genotypes except Li-2 suggesting the presence of a novel allele in Li-2 causing this abnormal phenotype.  We also observed different proportion of such abnormal phenotype in different generations (F₁, F₂, BC₁F₁) among the crosses of Li-2.  We detected the following proportion of abnormal plants with seeds producing different types of fibers in different branches of the same plant: Li-2 (22%), FM966 x Li-2 (F₁ 42%, F₂ 1%, BC₁F₁ 5%),  MD17 x Li-2 (F₁ 38%, F₂ 2%, BC₁F₁ 0.4%),  177 x Li-2 (F₁ 33%, F₂ 2%, BC₁F₁ 2%),  and 181 x Li-2 (F₁ 40%, F₂ 1%, BC₁F₁ 3%).  We observed this abnormal phenotype in both field and greenhouse condition.  This abnormal phenotype could be caused by different genetic effects including low penetrance or a tansposable element or some other cytogenetic abnormalities.