Submitted to: World Cotton Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 9, 2003
Publication Date: N/A
Technical Abstract: Improved Host Plant Resistance (HPR) has long been a goal of plant breeders. Despite the fact that improvements have been made by a number of researchers over the past 50 years, chemical control of insect pests has remained the preferred method for most production systems. The introduction of bt cotton and the pressure to decrease insecticide use has renewed interest in increasing the plant's endogenous defenses against various insect pests. A number of simply inherited traits have been identified that can improve the plant's defenses against various insect pests. Each individual trait is not enough to provide adequate protection, but in combination, should provide a defense network that will allow even less insecticides to be used. The traits being combined include semi-smooth leaf (t2t3) which deters some insects from feeding and inhibits egg laying, nectariless (ne1ne2) eliminates nectaries which are an insect attractant, high glanding (Gls3Gls3) produces glands on the calyx crown which decreases bud/bollworm feeding, and semi-glanded (gl2Gl3) decreases number of glands in seed, but has near normal glanding on other plant parts. The okra leaf (Lo2Lo2) trait has been suggested to make plants less attractive to bud/bollworm and impart better disease tolerance. To further evaluate these findings, both normal and okra leaf genotypes will be produced and tested. The parental material also has tolerance/resistance to Verticillium wilt, Fusarium wilt/Root knot nematode, and Bacterial blight. The parents chosen for combining the traits not only have the traits of interest, but also have good fiber properties and lint yield, thereby eliminating the need for extensive backcrossing to recover a line with acceptable agronomic characteristics. Instead, a forward-crossing scheme is being used where F2 plants from the first cross are crossed onto plants containing the next trait being incorporated. This process is repeated until all the traits have been combined into one line. This genotype building strategy emphasizes combining multiple traits into one line without trying to recover the original phenotype of any of the parental lines. Instead new combinations will be created and selections will be made within the resulting progeny. If the bt gene can be incorporated into these new breeding lines, HPR will be improved even more.