Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2005
Publication Date: 9/15/2005
Citation: Ruan, Y., Llewellyn, D.J., Furbank, R.T., Chourey, P.S. 2005. The delayed initiation and slow elongation of fuzz-like short fibre cells in relation to altered patterns of sucrose synthase expression and plasmodesmata gating in a lintless mutant of cotton. Journal of Experimental Botany. 56(413):977-984. Interpretive Summary: Sucrose synthase (SuSy) is an essential enzyme for proper utilization of sucrose in developing seeds, an important unit of crop yield. Our previous results have shown that the enzyme is also critical in developing cotton seed in fiber production. However, nothing is known on the nature of fiber if the plant fails to make SuSy enzyme by virtue of a mutation or an inactivation of the gene that codes for the enzyme. Based on a collaborative study between scientists from Crop Genetics & Environmental Research Unit in Gainesville, FL, and CSIRO Plant Industry, Canberra, Australia, the results show that fiber initiation and elongation is severely reduced or delayed if the plant fails to make sufficient levels of the SuSy enzyme. Overall, the study is important in the identification of key players in the production of cotton fiber, and showing through genetic evidence that SuSy is indeed critical in the initiation and elongation of fiber cells that develop on cotton seed.
Technical Abstract: Cotton (Gossypium hirsutum L.) seed develops single-celled long fibres (lint) from the seed coat epidermis at anthesis. Our previous studies have shown that the initiation and rapid elongation of these fibres requires the expression of sucrose synthase (Sus) and, potentially, a transient closure of plasmodasmata. This study extends the previous work to examine the patterns of Sus expression and plasmodesmata gating in fuzz-like short fibres of a mutant that shows delayed initiation and much slowed and reduced elongation of the fibre cells. Immunolocalization studies revealed delayed expression of Sus in the mutant seed coat epidermis that correlates temporally and spatially with the initiation of the fibre cells. Suppression of Sus expression in the seed coat epidermis of the transgenic plants reduced the length of both lint and short fuzz fibres at maturity, suggesting that the growth of short fibre also requires high level of Sus expression. Confocal imaging of the membrane revealed no closure of plasmodesmata during the entire elongation period of short fibres from the mutant seed. These results show the delayed initiation of fuzz like short fibre from the mutant seed correlates with delayed or insufficient expression of Sus in a subset of seed coat epidermal cells destined to become fibres