The Race Structure of the Rice Blast Pathogen Across Southern and Northeastern China

Abstract

BackgroundRice blast, caused by the ascomycete Magnaporthe oryzae (Mo), imposes a major constraint on rice productivity. Managing the disease through the deployment of host resistance requires a close understanding of race structure of the pathogen population.ResultsThe host/pathogen interaction between isolates sampled from four Mo populations collected across the rice-producing regions of China was tested using two established panels of differential cultivars. The clearest picture was obtained from the Chinese cultivar panel, for which the frequency of the various races, the race diversity index, the specific race isolate frequency, and the frequency of the three predominant races gave a consistent result, from which it was concluded that the pathogen population present in the southern production region was more diverse than that in the northeastern region. The four blast resistance genes Pi1, Pik, Pik-m, and Piz all still remain effective in the southern China rice production area, as does Pi1 in the northeastern region. The effectiveness of Pita, Pik-p, Piz, and Pib is restricted to single provinces. The distinctive resistance profile shown by the Chinese differential cultivar set implied the presence of at least five as yet unidentified blast resistance genes.ConclusionsThe Chinese differential cultivar set proved to be more informative than the Japanese one for characterizing the race structure of the rice blast pathogen in China. A number of well characterized host resistance genes, in addition to some as yet uncharacterized ones, remain effective across the major rice production regions in China.Electronic supplementary materialThe online version of this article (doi: 10.1186/s12284-017-0185-y) contains supplementary material, which is available to authorized users.

Dynamics of Race Structures of the Rice Blast Pathogen Population in Heilongjiang Province, China From 2006 Through 2015

“…Diseased rice panicles were sampled from fields across HLJ from 2006 to 2015. Standard methods (Zhang 2018;Zhang et al 2017) were used to both derive and store single-spore isolates of M. oryzae from these samples. The race structures of the three populations Pop-06, Pop-11, and Pop-15 were subjected to investigation of race structure dynamics over a decade.…”

“…Pathogen races (also referred to as physiological races or pathotypes) are defined by their interaction with a set of host cultivars that each carry a distinct profile of known major resistance genes (Atkins et al 1967;Feng et al 2018;Kolmer and Hughes 2018;Liu et al 2017;Wang et al 2017). Although a number of studies have addressed the race structure of certain plant pathogens, little attention has been paid to simultaneously characterizing both temporal and spatial dynamics of race structures (Chen et al 2001;Dorrance et al 2016;Kawasaki-Tanaka et al 2016;Kolmer and Hughes 2018;Liu et al 2017;Wang et al 2017;Yang et al 2004;Zhang et al 2017). Host resistance is often conditioned by a single gene.…”

“…It tends to follow the gene-for-gene model so that, when the resistance gene no longer recognizes a pathogen's avirulence gene owing to a change in that gene, the result is an abrupt loss in resistance, and disease ensues (Flor 1971;Wu et al 2014;Zhang et al 2015). Concomitantly, the deployment of new host resistance genes drives alterations in a pathogen's race structure (Mekwatanakarn et al 2000;Wang et al 2017;Wu et al 2014;Zhang et al 2015Zhang et al , 2017. Characterizing and monitoring the dynamics of pathogen population race structures can contribute to devising a sustainable strategy to control plant disease through the deployment of appropriate resistance genes (Hu et al 2002;Kawasaki-Tanaka et al 2016;Kolmer and Hughes 2018;Liu et al 2017;Wang et al 2017;Zhang et al 2017).…”

“…The area planted locally to rice increased from 1.99 million hectares (Mha; 6.9% of the national rice production area) in 2006 to 4.01 Mha (13.3%) in 2015; in terms of production, grain harvest has risen from 13.6 million tons (Mt; 7.5% of the national total) to 22.0 Mt (10.6%) (Zhang 2018). Rice blast caused by the heterothallic ascomycete Magnaporthe oryzae represents one of the most serious biotic constraints on yield in rice (Wang et al 2017;Zhang et al 2017;Zhao et al 2018). Although a previous study compared the race structure of the HLJ M. oryzae population with that present in other parts of China (Zhang et al 2017), the focus of this investigation was the characterization of the dynamic behavior of the HLJ M. oryzae population over the previous decade.…”

“…Rice blast caused by the heterothallic ascomycete Magnaporthe oryzae represents one of the most serious biotic constraints on yield in rice (Wang et al 2017;Zhang et al 2017;Zhao et al 2018). Although a previous study compared the race structure of the HLJ M. oryzae population with that present in other parts of China (Zhang et al 2017), the focus of this investigation was the characterization of the dynamic behavior of the HLJ M. oryzae population over the previous decade. To this end, the interaction between M. oryzae isolates sampled at various time points during the period 2006 through 2015 and a set of Chinese differential cultivars (CDCs) was tested.…”