Cotton Seed Development: Opportunities to Add Value to a Byproduct of Fiber Production

Unlike other major crops in which seeds provide most of the economic value, cotton seed is largely a by-product of more valuable fiber production and represents only approximately 15% of the farm gate value of the cotton crop. A cotton plant normally produces about 1.6 kg of seed for every kg of lint. Following ginning to remove the lint fiber, fuzzy cotton seed is either used directly as animal feed, or processed into four major products including oil, meal, hull and short linter fibers (Cherry and Leffler, 1984; O’Brien et al., 2005). With about 21% oil and 23% protein by weight in the seed, however, this makes cotton the fifth largest oil crop in the world and the second most important potential source of plant proteins. As a by-product of fiber production, the continued large scale production of cotton seeds is assured because of the on-going demand for the fiber by the textile industry. Until recently, the quality of cotton seed has been relatively neglected as the main research priority has been devoted to enhancing fiber quality and fiber yield. This continual human selection for high yield and better quality of fiber has narrowed the genetic variation available for cotton seed quality improvement through breeding. An in-depth understanding of metabolic events that determine the overall components of the storage reserves in cotton seeds is therefore of vital importance for improving the yield, quality and ultimately the value of seed products and opens the possibility for significant value-adding by engineering novel attributes into the seed. While in this review we have focused primarily on the development of the cotton seed, other more studied species such as Arabidopsis thaliana can serve as a model for cotton and for completeness those other species are mentioned where data for cotton are limited.