Cellulose Biosynthesis in Developing Cotton Fibers

It has often occurred to this writer that the fibers of cotton and the erythrocytes of animals share strikingly similar destinies. Both the erythrocyte and cotton fiber are terminally differentiating cells programmed to carry out one specific process at massive rates. Thus, the erythrocyte synthesizes massive amounts of a single protein, hemoglobin, while the cotton fiber devotes much of its later life to the synthesis of secondary wall cellulose. Because cotton fibers are unique cells that differentiate synchronously and synthesize so much cellulose at one stage of development, they have become one of the model systems of choice in plants for the study of the mechanism and regulation of cellulose synthesis. Furthermore, the study of cellulose synthesis in the cotton fiber has obvious practical implications because the timing, extent, and pattern of deposition of this polymer has a marked influence on fiber quality. This chapter will begin with a brief summary of what is known about the processes relating to cellulose synthesis as they occur in vivo during fiber development. Thereafter, the bulk of this chapter will concentrate on details of the biochemistry and molecular biology of the process of cellulose synthesis itself. In addition to other chapters in this book, the reader may wish to consult other sources on the process of cellulose biosynthesis and/or fiber development (Basra and Malik, 1984; Buchala and Meier, 1985; Ryser, 1985; Ross, Mayer, and Benziman, 1991; Delmer and Amor, 1995; Volman, Ohana, and Benziman, 1995; Brown, Saxena, and Kudlicka, 1996; Kawagoe and Delmer, 1997). Kawagoe and Delmer (1997) cite many older reviews as well, for those interested in studying some of the earlier literature on the topic.