Mapping-By-Sequencing the Genetic Locus of Short Fiber Mutant Ligon Lintless-y (liy)

A short fiber mutant Ligon-lintless-y was created after treating seeds of cotton line MD15 with ethyl methanesulfonate (EMS). Genetic analysis indicated that the mutation is controlled by a single recessive locus designated li_y. Besides causing short seed fibers, the mutation also affects other traits including plant height. From an F₂ mapping population derived from a cross between MD15 and liy mutant, we selected 100 short fiber progeny (li_y/li_y), and bulked their DNAs. We sequenced the genomes of this DNA bulk and their two parents. Sequence alignment analysis and SNP calling mapped the li_y locus on chromosome A12. In 2018, we enlarged F₂ populations, and mapped the liy locus within an interval of 6 Mb. We developed SNP and indel markers that are flanking the li_y locus. Fine mapping the li_y locus and identifying the causative gene of the liy mutation are in progress. We also evaluated global transcriptional changes during cotton fiber development at 3, 8 and 16 days post anthesis triggered by liy mutation. Gene set enrichment analysis revealed that many metabolic pathways, including carbohydrate, cell wall, hormone metabolism and transport were substantially altered in li_y developing fibers. We will present our results pertinent to genetic mapping of liy locus and identification of candidate causative genes for liy mutation.