Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 30, 2010
Publication Date: September 15, 2010
Citation: Taliercio, E.W., Scheffler, J.A., and Kwanyuen, P. 2010. Nitrogen Metabolism in Cotton Stems and Roots during Reproductive. Journal of Cotton Science. 14:107–112. Interpretive Summary: Cotton stems and roots store starch to act as reserves for growth and reproduction. We have demonstrated that cotton roots and stems may also provide nitrogen to support reproduction. Total nitrogen levels and soluble protein levels drop during flowering and seed set. During the same developmental period, levels of the amino acid aspartate increased. The expression of selected genes associated with protein turn-over and nitrogen transport also increase in cotton stems and roots during reproduction. We propose that transported forms on nitrogen from stems and roots provide a signal indicating the nitrogen status of the plant. This signal may affect seed set.
Technical Abstract: Cotton (Gossypium hirsutum) is a perennial plant grown as an annual row crop in much of the world. Cotton stems and roots store starch prior to reproduction that is subsequently available to support reproduction. Aspects of nitrogen metabolism in cotton stems and roots were investigated to determine whether these tissues also provided nitrogen to support reproduction. Measurements of total nitrogen, soluble proteins and individual amino acids indicated nitrogen metabolism was altered after flowering began. Analysis of expression of genes from previous microarray experiments and quantitative analyses of the expression of genes associated with amino acid biosynthesis, biosynthesis of nitrogenous compounds and protein turnover also showed patterns consistent with a role of altered nitrogen metabolism during seed set. We propose that stem and roots provide nitrogen to support reproduction and suggest that the transport of nitrogenous compound from these tissues to reproductive tissue could affect seed set by communicating the nitrogen status of the plant.