Journal de pathologie végétale et de microbiologie

Abstrait

Screening for Resistance to Crown Rust in Oat Genotypes through Morphological and Molecular Parameters

Yogesh Ruwali, Lalan Kumar and JS Verma

A collection of 20 oat genotypes from different sources were evaluated in small isolated field plots for crown rust severity in natural epidemics with virulent P. coronata isolates and further screened with linked molecular markers. Large variation was observed for disease severity under field conditions in spreader plot. Genotypes with partial resistance due to a reduction of disease severity in spite of a compatible interaction (rust score 3) and moderate susceptibility were identified. The twenty genotypes displaying the variable disease severity with visible necrosis were selected for further studies regarding presence or absence of major genes (Pc91 and Pc68) for resistance to crown rust. In field nurseries, on the basis of latency period and disease severity (DS) none of the twenty genotypes fell into the resistant pool (score 1). Most of them showed a prolonged latency period, reduced infection frequency and colony size, and increased percentage of early aborted colonies not associated with host cell necrosis. Result on screening for crown rust resistance in field screening and by linked markers showed the absence of major resistance gene in the target population, several advance lines were identified as moderately resistant to crown rust reaction.