Map-Based Cloning of the Major Leaf Shape Gene (LO-D1) in Upland Cotton (Gossypium hirsutum L.)

Leaf shape in Upland cotton (Gossypium hirsutum L.) is an important trait that influences yield, earliness, flowering rate, disease resistance, and the efficacy of foliar chemical application. A complete understanding of the genetic mechanism controlling leaf shape is essential for its proper manipulation to develop a cotton ideotype that maximizes yield while minimizing inputs. Developmental aspects of classical leaf shapes of cotton have also been longstanding interest to plant biologists. Predominant leaf shapes normal, sub-okra, okra, and super-okra, with varying levels of lobe severity, are controlled by a multiple allelic series at the D-genome locus L-D₁. Using a combination of various mapping techniques, expression and sequence analyses, virus-induced gene silencing, mutagenesis, and morphometric analysis, modifications to a LMI1­-like transcription factor were shown to condition the major leaf shapes of Upland cotton. Results on gene expression, nucleotide changes and the possible origin of nucleotide diversity for different leaf shapes of the L-D₁ locus will also be presented.