Resistance of tobacco to pandemic blue mould Peronospora hyoscyami de Bary syn P. tabacina Adam): a historical overview

Abstract

Summary. The pandemic of Peronospora hyoscyami de Bary (syn. P. tabacina Adam) introduced into Britain from Australia in 1957 swept across Europe, North Africa, the Middle East and the former Soviet Union in the early 1960s causing catastrophic losses of tobacco crops. Nicotiana debneyi Domin. is the major source of resistance to this pathogen in Australia and Europe.

A blue mould resistant version of USA cultivar Hicks (designated Resistant Hicks) was bred by H. W. Lea. This cultivar, with resistance from N. debneyi was widely used in Europe from 1962 as a parent with local varieties. From 1965 Bel 61 lines bred by the United States Department of Agriculture, also with resistance from N. debneyi were phased in as a source of resistance in some countries. The cultivar Resistant Hicks was selected for resistance in growing seasons with few cloudy days, and its high resistance in Australia has been stable for over 40 years; the cultivar Dynes mostly grown in Australia has the Resistant Hicks source of resistance. The high resistance to Peronospora possessed by cultivars developed from the Bel 61 lines has been stable for more than 20 years in Europe; the Bel lines were selected under shade conditions.

Nicotiana debneyi has resistance to Peronospora hyoscyami on 8 chromosomes; there is evidence that both American and Australian resistant cultivars derive some resistance from Nicotiana tabacum L. Both the cultivar Resistant Hicks and Bel 61 lines possess only part of the full resistance available from N. debneyi; further progress may be possible by hybridising these 2 lines and incorporating resistance from other resistant Australian species.