VIEW ARTICLE

Resistance

The Role of Delphinidin and Sugars in the Resistance of Pea Seedlings to Fusarium Root Rot. J. M. Kraft, Research Plant Pathologist, Agricultural Research Service, U. S. Department of Agriculture, Western Region, Irrigated Agriculture Research & Extension Center, Prosser, Washington 99350; Phytopathology 67:1057-1061. Accepted for publication 4 March 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1057.

Pea seed and seedling exudates and extracts from testae of all Plant Introduction accessions with the A gene for anthocyanin production, whether resistant or susceptible to Fusarium root rot, contained the anthocyanidin (anthocyanin-aglycone) pigment delphinidin. Delphinidin, located primarily in the testae of all P. I. accessions tested, was fungistatic to conidial germination of Fusarium solani f. sp. pisi. In a bioassay, the pathogen was able to germinate in the presence of delphinidin when glucose was present in sufficient amounts. These results suggest that P. I. accessions, with the A gene, can be susceptible in the seedling stage, despite the presence of delphinidin if they exude sufficient sugar.