Resistance to Puccinia polysora in Zea mays L. : identification, genetic transmission (linkages) and induced molecular responses

Abstract

The objectives were broad in scope, but they centered around the theme of disease resistance. In Chapter 2, the techniques used in evaluating the general resistance (pustule density and AUDPC) were shown to be efficient. General resistance to P. polysora was shown to be common, though quite variable, among 33 inbreds and 23 single-crosses tested. In Chapter 3 reciprocal translocations were used to identify linkage groups affecting general resistance. Test results suggest chromosomes 4, 8 and 9 of B73 and 2, 4 and 7 of Mo17 contribute to general resistance. Chromosome 9 was also linked to resistance in Tx5855 and B37. In several cases resistance was linked to chromosomes of the translocation stocks themselves. These include chromosomes 1, 5, 7 and 8. Chapter 4 provided few answers but many questions. An experimental basis for further study into the biochemical nature of disease resistance was established. Techniques required to investigate disease resistance at the molecular level were developed and results of initial experiments are discussed. These studies demonstrate the range of investigations which need to be carried out in seeking a solution to plant disease problems. Although the genetic basis for general resistance is complex, the molecular procedures used appear suitable for studies concerning the biochemical nature of both general and complete resistance.