Evaluating diverse systems of tobacco genetic resistance to Phytophthora nicotianae in Yunnan, China

Abstract

Black shank, caused by the soilborne pathogen Phytophthora nicotianae, is one of the most devastating diseases affecting tobacco production in China. The most effective strategy for reducing economic loss from this pathogen is development and use of resistant tobacco varieties. Multiple sources and systems of resistance have been developed in the Western Hemisphere; however, populations of P. nicotianae are variable around the world, including the predominance of different races. Different P. nicotianae isolates may react differently on tobacco plants with different systems of resistance, a possibility that could complicate the breeding of cultivars with resistance that is effective in different tobacco production regions worldwide. The objective of this research was to evaluate an array of tobacco germplasm possessing different systems of genetic resistance to black shank disease in tobacco‐growing regions of Yunnan, China. Resistance types included simply inherited resistance mechanisms introgressed from wild Nicotiana relatives and polygenic partial resistance systems of N. tabacum origin. The loci of Wz exhibited high level resistance to black shank in the five diverse disease environments in Yunnan, China. K326 Php/−Wz/− genotype and Beinhart 1000 exhibited the greatest levels of resistance in both 2015 and 2016. Field observed results for 13 tobacco genotypes were highly correlated with those tested in growth chamber evaluation. These findings suggest that both Wz− and Beinhart 1000‐mediated resistance have important commercial value in flue‐cured tobacco breeding programmes in China. Cultivars developed for black shank resistance in China may also have utility in other tobacco‐growing areas.

Quasi-targeted metabolomics revealed isoliquiritigenin and lauric acid associated with resistance to tobacco black shank

“… 2 , 10 , 11 Tobacco cultivars resistant to TBS can be categorized into multiple types: those with resistance conferred by multiple quantitative trait loci (QTLs) primarily derived from “Florida 301” and “Beinhart 1000”, those with resistance mediated by single homologous genes (such as the phl gene from N. longiflora and the php gene from N. plumbaginifolia ), and those with resistance governed by a single dominant resistance locus Wz from N. rustica . 2 , 10 It is worth noting that the cultivar K326 resistance was sourced from the “Florida 301”. Grafting, where highly resistant plants serve as rootstocks and high-yield crops as scions, can avoid the above problems to some extent 12 and improve fruit quality.…”