Brassinosteroid Regulates Fiber Development on Cultured Cotton Ovules

Abstract

Our current understanding of the role of phytohormones in the development of cotton fibers is derived largely from an amenable culture system in which cotton ovules, collected on the day of anthesis, are floated on liquid media. Under these conditions, supplemental auxin and gibberellin were found to promote fiber initiation and elongation. More recently, addition of low concentrations of the brassinosteroid brassinolide (BL) were also found to promote fiber elongation while a brassinosteroid biosynthesis inhibitor brassinazole2001 (Brz) inhibited fiber development. In order to elucidate the role of brassinosteroid in cotton fiber development further, we have performed a more detailed analysis of the effects of these chemicals on cultured cotton ovules. Our results confirm that exogenous BL promotes fiber elongation while treatment with Brz inhibits it. Furthermore, treatment of cotton floral buds with Brz results in the complete absence of fiber differentiation, indicating that BR is required for fiber initiation as well as elongation. Expression of fiber genes associated with cell elongation increased in ovules treated with BL and was suppressed by Brz treatment, establishing a correlation between brassinosteroid-regulated gene expression and fiber elongation. These results establish a clear connection between brassinosteroid and fiber development and open the door for genetic analysis of cotton development through direct modification of the brassinosteroid signal transduction pathway.

Proteomic Identification of Differentially Expressed Proteins in the Ligon lintless Mutant of Upland Cotton (Gossypium hirsutum L.)

“…Diverse signal transduction pathways were found to be involved in the regulation of fiber elongation including ethylene-, brassinosteroid (BR)-and auxin-mediated signalings. 5,8,45,46 We have previously reported that calcium signaling components such as calmodulin, CBL (calcineurin B-like protein) and CDPK (Ca 2+ -dependent protein kinase) are up-regulated during fiber elongation. 47,48 Here we found that the expression of a calmodulin was highly suppressed in Li 1 fiber, thus further demonstrating the role of calcium signaling in fiber elongation.…”

Plant Wnt:Deciphering a Novel Signalling Pathway in Plants

“…On the contrary, based on the signalling pattern, Br signalling in plants has been correlated with metazoan Wnt like signalling. It is reported that Br is involved in the process of callusing, somatic embryogenesis 82 and promotes fibre initiation and elongation in Gossypium 83,84 . This role of Br is rather comparable to that of Wnt's action in animals where Wnt promotes embryogenesis and cell reprogramming.…”

Effects of light on in vitro fiber development and flavonoid biosynthesis in green cotton (Gossypium hirsutum)

“…Fiber length was measured using the water washing method [26]. The ovules were boiled in water for 2 min to detach fibers, and after cooling, the ovules were placed on a slide and rinsed with purified water.…”