Working group session:
Functional Genomics
Presentation type:
15 minute Oral
Author Affliation:
CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT 2601, Australia
CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW 2390, Australia
CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT 2601, Australia
CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT 2601, Australia
Abstract:
Cotton fibres arise from the epidermal cells of the seed coat and may be either long (lint) or very short (fuzz). Both lint and fuzz are single-celled and indistinguishable in appearance during the early stages of their growth, suggesting that their growth may involve the same physiological and biochemical processes that are regulated by the same set of genes. The dominant fuzzless mutation N1 of tetraploid Gossypium hirsutum has been demonstrated to be a defective allele of the At-subgenome homoeolog of MYB25-like, a master gene regulating fibre initiation as silencing MYB25-like resulted in lintless and fuzzless seeds. We recently identified five genetic loci, including a major contributing locus containing MYB25-like_Dt, associated with the recessive fuzzless seed trait n2 in G. barbadense based on genotyping (SNP chip and mapping-by-sequencing) of fuzzy and fuzzless near isogenic lines (NILs) derived from an interspecies cross (G. barbadense x G. hirsutum). We compared the expression changes of MYB25-like_At and MYB25-like_Dt during fibre development in cotton accessions with different fibre phenotypes. At 3 dpa (days-post-anthesis) when fuzz fibres are initiating, expression of MYB25-like_Dt was significantly lower in fuzzless NILs than in fuzzy seeded NILs, while higher MYB25-like_Dt expression was associated with more seed fuzz across different cotton genotypes. Phenotypic and genotypic analysis of MYB25-like homoeoalleles in cottons showing different fibre phenotypes and their crossing progeny indicated that both MYB25-like_At and MYB25-like_Dt are associated with lint development, and that fuzz development is mainly determined by the expression level of MYB25-like_Dt at ~3 dpa, suggesting that cotton lint and fuzz development are regulated by the temporal expression of MYB25-like homoeologs. In this presentation, we will propose a working model for the role of MYB25-like homoeologs in lint and fuzz development, and discuss strategies for confirmation of the contributions of MYB25-like homoeologs to lint and fuzz development.