Towards Breeding Strong but Fine Cotton Fibers with a Little Help from WLIM1a

摘要

The cotton (Gossypium hirsutum) fibers in that comfy sweater of yours developed from single epidermal cells of the cotton seed coat. Mature cotton fiber cells are extremely long (up to 3 to 5 cm). During the fast elongation stage, the length of the cotton fiber increases to 1000 to 3000 times the diameter of the cell (Meinert and Delmer, 1977). Accomplishing this task requires the formation of actin bundles, which serve as tracks to transport the large amount of materials needed for fiber elongation. The fast elongation stage ends with a reactive oxygen species burst, leading to the onset of secondary cell wall synthesis. Indeed, a cotton fiber is primarily occupied by the secondary wall, which mainly consists of cellulose and some minor noncellulosic carbohydrates. While a fair amount is known about cotton cell elongation (Li et al., 2013), little is known about secondary wall formation, a process that largely determines the fineness and strength of the fiber. Not surprisingly, a negative correlation is often observed between cotton fiber fineness and strength; the concurrent improvement of these traits represents a bottleneck in cotton breeding.