Poster: Vegetative development

Abs # 331: Analysis of global gene expression during fiber initiation in cotton

Presenter:	Arpat, A. Bulak , abarpat@ucdavis.edu
Authors	Arpat, A. Bulak  (A)   Wilkins, Thea A (A)
Affiliations:	(A): Department of Agronomy and Range Science, University of California, Davis

Initiation of cotton fibers, which are unicellular seed trichomes, is the first phase of fiber development. A better understanding of the initiation process will not only help improving commercially important fiber characteristics such as fiber yield, but also expand our knowledge in fundamental biological phenomena such as plant cell differentiation and morphogenesis. Initiation phase, which is observed as the appearance of trichome primordia in the epidermal layer at the day of anthesis, is a product of differentiation and expansion of ~30% of epidermal cells. To study the gene regulation during fiber initiation, we used comparative microarray analysis spanning the early developmental frame including initiation in wild type and mutants with altered fiber initiation. Two isogenic ‘naked’ mutants, N1N1 and n2n2, in TM-1 background are characterized by their lack of fuzz fibers and reduced fiber yield. Both N1N1 and n2n2 show altered onset of initiation and reduced number of fiber initials, the former being more severe. The double-mutant, N1N1n2n2, produces a novel phenotype and is ‘fiberless’, which lacks both fuzz and lint fibers. We used oligonucleotide microarrays consisting of ~12,200 unique probes designed from 46,603 expressed sequence tags (ESTs) to compare global gene expression during the initiation phase of the fiber mutants and wild type cotton. Multifactorial hybridizations were designed based on multiple-loops with dye-swap and analyzed using linear regression methods. Cluster analysis of differentially expressed genes provides a list of candidate genes for fiber initiation in cotton.