The Effect of Constitutively over-Expressing the Gene for Tomato Fructokinase (LeFRK1) on Cotton Yield in Greenhouse and Field Trials

Cotton yield depends on cellulose synthesis during fiber cell-wall development.  Sucrose synthase (SuSy) cleaves sucrose to provide UDP- glucose for cellulose synthesis.  Fructose is the other product of the reaction and inhibits SuSy.  Fructose can be removed by the enzyme fructokinase (FRK).  Increasing the FRK activity by constitutively over-expressing a tomato FRK gene (LeFRK1) increased seed cotton yield per boll over the non-expressing, control genotype by 40 to 90% in greenhouse and 10 to 30 % in field trials.  Associated with the increase in seed cotton yield was an increase in both seed number and fiber mass per boll.