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Stagonospora nodorum blotch (SNB) is a significant fungal disease of bread wheat (Triticum aestivumL.) caused by Stagonospora nodorum, in which reduced grain yield is caused when the pathogen infects flag leaves and glumes at the critical time of grain filling. Wheat breeding programs have made limited progress in improving resistance to SNB due to the underlying complexity of the pathogen, host resistance, and their interactions. There has been an increase in knowledge of components of host–pathogen interactions in the past five decades, including pathogen diversity, biological factors contributing toward pathogen infection, environmental conditions favoring disease progression, and the genetics of host resistance. This review captures major outcomes and assesses different approaches and methodologies for improving resistance to SNB. The review concludes by proposing strategies for deploying, selecting, and combining gene and trait combinations in genetic backgrounds and improving methods for evaluation and selection of SNB resistance in wheat breeding.

Fluorescencein situ hybridization (FISH) has been used to analyse the structure of the rye B chromosome. Genomicin situ hybridization (GISH) demonstrates the high level of overall similarity between A and B chromosomes of rye, as well as the presence of a number of specific sequences. The B-specific repeat families D1100 and E3900 have been analysed in terms of their physical location and possible contiguity. Rye Bs contain members of the rye-specific dispersed repetitive family R173, as well as centromeric regions similar to those of the As. The B chromosomes analysed in our study lack detectable rDNA sequences. Anomalous results have been obtained with a number of subtelomeric repetitive probes from rye. Bs usually lack these sequences, but evidence is presented that in some cases A–B translocation events may relocate such sequences from the As to the Bs. These data are discussed in the context of current models for the origin of the B chromosome.