Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Experiment Station
Publication Acceptance Date: 5/21/1998
Publication Date: N/A
Technical Abstract: Sugarbeet tap roots rot when infected by the fungus Rhizoctonia solani at warm temperatures. Development of rot ceases at cool temperatures, and antimicrobial compounds accumulate in noninfected tissues around the rot as part of a defense response. Production of new or thicker cell walls may also be a part of this defense response. Recent evidence shows that the complex sugars raffinose, stachyose and verbascose are involved in the production of cell walls. Experiments were done to determine if these complex sugars accumulate in tissues that are showing the defense response. Only low concentrations of the complex sugars were found in healthy or rotted tissues of diseased tap roots. Within rotted roots at cool temperatures, concentrations of the complex sugars increased in tissues showing the defense response, immediately adjacent to rotted tissue, but not in tissue more than 1/4 inch away from the rot. These results show that production of new or thickened cell walls may be an important part of the plant's defense against Rhizoctonia. Control of this process through genetic engineering could improve plant resistance to the disease.