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Submitted to: Gene
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/21/2017 Publication Date: 5/21/2017 Citation: Naoumkina, M.A., Hinchliffe, D.J., Fang, D.D., Florane, C.B., Thyssen, G.N. 2017. Role of xyloglucan in cotton (Gossypium hirsutum L.) fiber elongation of the short fiber mutant Ligon-lintless-2 (Li2). Gene. 626:227-233. Interpretive Summary: Xyloglucan is a matrix polysaccharide found in the cell walls of all land plants. In growing cells, xyloglucan is thought to connect cellulose microfibrils and regulate their separation during wall extension. Ligon lintless-2 (Li2), a monogenic dominant cotton fiber mutation, that causes extreme reduction in lint fiber length with no pleiotropic effects on vegetative growth, represents an excellent model system to study fiber elongation. To understand the role of xyloglucan in cotton fiber elongation we used the short fiber mutant Li2 and its near isogenic wild type for analysis of xyloglucan content and expression levels of xyloglucan-related genes in developing fibers. The results in this study suggest an important role of XG for cotton fiber elongation. The early activation of xyloglucan-related genes and down regulation of xyloglucan degradation genes during the elongation phase leads to elevated accumulation of xyloglucan that restricts elongation of fiber cells in the short fiber Li2 mutant line. Technical Abstract: Xyloglucan is a matrix polysaccharide found in the cell walls of all land plants. In growing cells, xyloglucan is thought to connect cellulose microfibrils and regulate their separation during wall extension. Ligon lintless-2 (Li2), a monogenic dominant cotton fiber mutation, that causes extreme reduction in lint fiber length with no pleiotropic effects on vegetative growth, represents an excellent model system to study fiber elongation. To understand the role of xyloglucan in cotton fiber elongation we used the short fiber mutant Li2 and its near isogenic wild type for analysis of xyloglucan content and expression levels of xyloglucan-related genes in developing fibers. Accumulation of xyloglucan was significantly higher in Li2 developing fibers than in wild type. Genes encoding enzymes for nine family members of xyloglucan biogenesis were identified in the draft Gossypium hirsutum genome. RNAseq analysis revealed that most differentially expressed xyloglucan-related genes were down-regulated in Li2 fiber cells. RT-qPCR analysis revealed that the peak of expression for the majority of xyloglucan-related genes in wild type developing fibers was 5-16 days post anthesis (DPA) compared to 1-3 DPA in Li2 fibers. Thus, our results suggest that early activation of xyloglucan-related genes and down regulation of xyloglucan degradation genes during the elongation phase lead to elevated accumulation of xyloglucan that restricts elongation of fiber cells in Li2. |
