Population Structure And Primary Inoculum Of Pathogen Of Fusarium Head Blight On Wheat In Southern China

Fusarium Head Blight(FHB)is a devastating disease of wheat(Triticum aestivum L.),barely,oat,rye and triticale in humid and semi-humid parts of the world.In these crops,especially in wheat,FHB causes reduction in yield and grain quality,and the harvested grains are often contaminated with mycotoxins,such as trichothecenes.Consumption of these grains and products might have pernicious effects on humans and animals health.In this study,the composition of species and trichothecence chemotypes,genetic structure of predominant populations among rice stubble,weeds and wheat heads were compared and analyzed.The aim of this study is to know the population structure and primary inoculum of pathogen of Fusarium head blight on wheat in southern China,reveal the selection effect of overwintering hosts on Fusarium population,expand the period for the prevention and control of FHB and control the FHB by adjusting rotation systems.1.Comparative analysis of population structure of FHB pathogens from rice stubble and wheat in rice-wheat rotation areasWe collected diseased ears of wheat and rice stubble from same sampling sites from 9 sampling sites in 5 provinces,then identified species and the trichothecence chemotype on 1246 strains.This result indicated a significant correlation between Fusarium population structure from wheat and those from rice,which revealed that the perithecia on rice stubble were the primary inoculum of FHB on wheat in the ricewheat rotation areas.It is clarified that 3ADON producers of F.asiaticum were more prevalent on wheat,and rice was the preferred niche for NIV mycotoxin producers.2.Distribution characteristics of F.asiaticum in non-wheat producing areasThrough the whole genome sequencing of the predominant population in non-wheat producing areas of Hunan,Fujian,Guangxi and wheat producing areas in the Yangtze River Basin,it was found that the geographical isolation and rotation systems had a significant impact on the F.asiaticum population structure,and 3ADON producers of F.asiaticum from the middle and lower reaches of Yangtze River and 3ADON producers from Hunan are the same population,which means outcrossing occured between strains from wheat producing areas and non-wheat producing areas.Compared with 3ADON population,most of NIV producers was an independent population,a rich diversity and a significant genetic subdivision within the group.Based on the special geographical conditions and complicated farming methods in Sichuan,there were significant differences between populations in this region and those in other regions.At the same time,the NIV producers from Fujian and Hunan also had genetic subdivision.3.Comparative analysis of population structure of F.asiaticum from weeds and wheat in the Southwest and middle and lower reaches of the Yangtze riverWe collected the diseased ears of wheat and weeds from 48 sampling sites in Hubei and Sichuan,then identified species and the trichothecence chemotype on 893 strains.It was found that F.asiaticum dominated on both wheat and weed populations.Variable number of tandem repeats(VNTR)analysis of the predominant populations showed that weed populations showed a higher diversity than wheat populations,which indicated that Fusarium completed sexual reproduction on weeds was an important way to maintain population diversity.The analysis of linkage disequilibrium indicated that Fusarium populations from weeds and wheat were the same population,which proved that the perithecia on weeds were the primary inoculum of FHB on wheat.Based on bayesian modle,the test strains can be divided into two independent populations.The population composition was partially correlated to the trichothecence chemotype.The results showed that wheat was the preferred niche for POP1 population,while weeds had preference for the POP2 population.