Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Other
Publication Acceptance Date: December 29, 2001
Publication Date: N/A
Interpretive Summary: Disease and pest problems, as well as, leveling off of increases in sugar content over the last two decades are largely responsible for lack of increased sugar production from sugarbeet. Sugarbeet and many other crops lack resistant germplasm against various bacterial, fungal and insect pests, necessitating the use of chemical pesticides. Genes from other living organisms have been identified and shown to enhance disease and pes tolerance when incorporated into other plants using biotechnological approaches. We have taken a number of these genes and modified them for incorporation into sugarbeet to target fungal and bacterial pathogens such as Cercospora beticola, Rhizoctonia solani and Erwinia caratovora. We are also using genes that are effective against the sugarbeet root maggot and virus-transmitting aphids. For this purpose, we have developed and are optimizing two sugarbeet transformation methods. This research will be used by scientists to devise environmentally friendly approaches for the control of sugarbeet pests and disease-causing microbes leading to increased yields and sucrose productivity.
Technical Abstract: One of the most devastating pests of sugarbeet in the U.S. is the root maggot (Tetanops myopaeformis Roder). Losses can be as high as 23% in infested fields and are speculated to increase in the next few years due to the anticipated removal of all chemical pesticides effective against the maggot from EPA approved registrations. Currently no biological control measures are available. Introduction of multiple resistance genes into transgenic plants will most likely prove to be the most effective and perhaps sustained means of controlling diseases and insect infestations. One approach to insect control is to express proteinase inhibitor genes in transgenic plants to specifically target the insect's digestive proteases leading to inhibition of catalysis of dietary proteins essential for normal insect growth and development. To target the sugarbeet root maggot, we are in the process of determining the nature of the maggot's digestive proteases. Extracts of midguts excised from feeding second instar larvae were analyzed for specific protease classes using an inhibition assay. Most of the gut protease activity was inhibited by proteinase inhibitors specific for two classes of proteases. Further research is in progress to identify specific proteinase inhibitor genes for introduction into sugarbeet.