IDENTIFICATION AND CHARACTERIZATION OF A DIRIGENT PROTEIN THAT CONTROLS THE BIOSYNTHESIS OF (+)-GOSSYPOL IN COTTON
Insect Control and Cotton Disease Research Unit
2011 Annual Report
1a.Objectives (from AD-416)
1. Express cDNAs isolated from cotton that code for dirigent proteins in an insect/plant tissue culture system and assay for dirigent activity including the biosynthesis of (+)- or (-)-gossypol.
2. Transform cotton plants to optimize (+)-gossypol formation.
1b.Approach (from AD-416)
Cooperator will express appropriate cDNA sequences from cotton provided by the ARS cooperator in an insect/plant tissue culture system and test their activity for formation of (+)- or (-)-gossypol.
The goal of this project is to identify and characterize internal factors in cotton that control the biosynthesis of the gossypol form that is minimally toxic to non-ruminant food animals. Work during FY 2011 focused on the flower petals of Gossypium hirsutum var. marie galante, which are known to produce gossypol with a high percentage of the (+)-enantiomer, which is the relatively non-toxic form of gossypol. While this particular cotton type normally flowers only during the second year after planting, we were successful in obtaining flowers the first growing season. The petals from these flowers were collected under sterile conditions and immediately frozen in liquid nitrogen. As expected, the (+)-gossypol percentage in the petals from one plant was approx. 96%; however, the (+)-gossypol percentage in the petals from the second plant was approx. 60%. Petals from both plants were shipped to the cooperator for RNA analysis. Ongoing work by this project will make significant advances in understanding the genetic control of the (+)- and (-)-gossypol ratio in seed, and will provide foundational information for work to develop new cotton cultivars with low (-)-gossypol seed that can be safely fed to non-ruminant animals and thus expand utilization of cottonseed and enhance profitability of U.S. farmers.
The ADODR of this project and the cooperator (or key personnel working under the cooperator) interact through phone conversations and e-mails on a regular basis to discuss the direction and progress of the work.