Abstract
Each cotton fiber is a single-celled seed trichome or hair, and over 20,000 fibers may develop semi-synchronously on each seed. The molecular basis for seed hair development is unknown but is likely to share many similarities with leaf trichome development in Arabidopsis. Leaf trichome initiation in Arabidopsis thaliana is activated by GLABROUS1 (GL1) that is negatively regulated by TRIPTYCHON (TRY). Using laser capture microdissection and microarray analysis, we found that many putative MYB transcription factor and structural protein genes were differentially expressed in fiber and non-fiber tissues. Gossypium hirsutum MYB2 (GhMYB2), a putative GL1 homolog, and its downstream gene, GhRDL1, were highly expressed during fiber cell initiation. GhRDL1, a fiber-related gene with unknown function, was predominately localized around cell walls in stems, sepals, seed coats, and pollen grains. GFP:GhRDL1 and GhMYB2:YFP were co-localized in the nuclei of ectopic trichomes in siliques. Overexpressing GhRDL1 or GhMYB2 in A. thaliana Columbia-0 (Col-0) activated fiber-like hair production in 4–6% of seeds and had on obvious effects on trichome development in leaves or siliques. Co-overexpressing GhRDL1 and GhMYB2 in A. thaliana Col-0 plants increased hair formation in ∼8% of seeds. Overexpressing both GhRDL1 and GhMYB2 in A. thaliana Col-0 try mutant plants produced seed hair in ∼10% of seeds as well as dense trichomes inside and outside siliques, suggesting synergistic effects of GhRDL1 and GhMYB2 with try on development of trichomes inside and outside of siliques and seed hair in A. thaliana. These data suggest that a different combination of factors is required for the full development of trichomes (hairs) in leaves, siliques, and seeds. A. thaliana can be developed as a model a system for discovering additional genes that control seed hair development in general and cotton fiber in particular.
Highlights
Cotton fiber is the largest renewable source of textile materials, a sustainable alternative to petroleum-based synthetic fibers
Leaf trichome initiation in Arabidopsis thaliana is promoted by the positive transcription regulators GLABROUS1 (GL1), TRANSPARENT TESTA GLABRA1 (TTG1), GLABRA3 (GL3), and ENHANCER of GL3 (EGL3) that are counteracted by the negative regulators TRIPTYCHON (TRY), CAPRICE (CPC), and ENHANCER of TRY and CPC1 (ETC1, 2, and 3) that encode single MYB-domain protein families [2,3,4,5,6]
Using the cotton spotted long oligonucleotide microarrays with probes of many fiber ESTs developed in previous studies [16,20,21], we studied expression of fiber-related genes in ovules, protodermal fiber cells, and fiber cell initials by laser capture microdissection (LCM) (Figure S1, A and B)
Summary
Cotton fiber is the largest renewable source of textile materials, a sustainable alternative to petroleum-based synthetic fibers. Cotton seed hair development share many similarities with Arabidopsis leaf trichome development [1], which is mediated by a ‘‘trichome activation complex’’. GLABROUS2 (GL2) functions downstream of the GL1/TTG/GL3 complex and plays a role in leaf trichome development [3,7]. Some MYB factors such as AtMYB5 and AtMYB23 have minor effects on trichome initiation but regulate mucilage biosynthesis and seed coat development [8]. Trichome genes such as TTG1 and GL2 affect mucilage biosynthesis and columella cell formation [9,10], suggesting a role of these trichome genes in seed coat development [11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
