The importance of carbon flux and allocation in the growth and development of crop plants is the primary determinant of crop yield and in most cases, quality. Carbon flux proceeds via a series of spatially- and temporally-regulated enzymes which yield varying biochemical intermediates depending on the needs of the cell. Altering these needs or the signaling pathways that relay the information may allow for critical redirections of photo-assimilate towards increased crop yield under varying environmental conditions. An understanding of molecular mechanisms underlying source/sink relationships in plants may provide insights into increasing the use and efficiency of photo-assimilate, therefore increasing yield and quality. The cotton fiber has provided a unique platform for the study of cellulose biogenesis from a single celled genomic perspective. Through the use of various cotton mutants, analysis of carbon flux from source leaves to sink fibers will reveal key players and signaling pathways related to fiber development and potentially allow for the fiber developmental program to be “re-wired” to favor the deposition of cellulose into cotton fibers independently of environmental factors.