The growth of wild-type and genetically-marked strains of Tilletia caries and T. controversa in susceptible and resistant wheat cultivars

Graduation date: 1985The objective of this study was to provide basic\ud information on the interaction of the bunt fungi\ud Tilletia caries and T. controversa with their host,\ud Triticum aestivum. Studies on the ability of haploid\ud strains to colonize wheat heads provided the basis for\ud experiments in which haploid strains were crossed in\ud planta. Wild-type and genetically-marked haploid\ud strains of T. caries and T. controversa injected into\ud boot-stage heads of susceptible and resistant wheat\ud cultivars were recovered from the mature heads 4 to 6\ud weeks after introduction. Viable teliospores were\ud produced following successful matings of sexually\ud compatible haploid cultures of T.caries and\ud T.controversa injected into boot-stage heads which were\ud grown both in intact plants and in an organ culture\ud system for wheat heads. The organ culture system\ud adopted here was determined to simulate natural\ud infection under controlled environmental conditions.\ud It served as a basis for the production of hybrid\ud teliospores formed between strains of T. caries and\ud T. controversa.\ud The kinetics of teliospore germination of\ud T. caries, T. controversa and hybrids formed by the\ud cross of T. caries, and a genetically-marked strain of\ud T. controversa, were determined. The time required for\ud germination of the hybrid teliospores at 4C was\ud intermediate to that of the parents, suggesting that\ud this trait may be controlled by a single gene which\ud exhibits incomplete dominance. Teliospores of the Fl\ud generation failed to germinate at 18C suggesting that\ud this trait is controlled by a dominant gene present in\ud the T. controversa parental strain. The genetic marker\ud was recovered in the Fl generation, indicating that\ud drug-resistance markers may be used in future crosses