| Camellia oleifera is a unique woody edible tree species in southern China.Camellia oleifera anthracnose is one of the important diseases in camelliera production,which seriously affects the yield and quality of camellia oleifera.In this study,997 leaves from oil-tea producing areas were collected,and about 2000 strains of pathogenic bacteria were isolated.104 strains of Camellia oleifera anthracnose were screened out by morphological characteristics and Koch’s law.The Ap-Mat gene fragment sequence was used as the marker basis for classification,through sequence comparison and genetic analysis,the genetic evolution direction of anthracnose in camellia oleifera was discussed and analyzed,and the genetic structure characteristics of anthracnose in camellia oleifera in different regions in China were analyzed.Using SSR molecular markers of leaf DNA,sequence analysis was carried out on camellia oleifera strains in different regions of China,the germline relationship between anthrax bacteria and host camellia oleifera was studied,and the diffusion path caused by gene exchange was predicted.The results provided a theoretical basis for the interaction between camellia oleifera anthracnose and its host.The main conclusions are as follows:(1)genetic diversity and population genetic structure of anthrax in camellia oleifera.104 strains of anthrax were isolated from 22 samples from 9 provinces in China,all of which could cause disease of oil tea and fruit.Population genetics of 104 strains of anthrax were analyzed based on Ap-Mat gene sequence.Polymorphism analysis showed that there were 8 genotypes of anthrax in hainan,which was the highest in each province.On the contrary,there are only two genotypes in hubei,and it can be seen from phylogenetic trees that hubei is both fruity and fructicola,indicating that hubei province is the region with the lowest abundance and most stable.By a neutral inspection we also found significant genetic differentiation between different geographic population statistical phenomenon,hubei,jiangxi region and the yunnan region population neutral inspection reach the statistically significant level,hubei and jiangxi Taijima’s D,Fu&Li’s D*and Fu&Li’s F*values are negative,illustrate the oil-tea anthrax bacteria group,there are a large number of low-frequency allele loci,have the phenomenon of population expansion in history.It can be seen that anthrax bacteria in camellia oleiflora spread radially from central hubei and jiangxi,and the degree of differentiation ranged from mild to severe.There were 20 haplotypes and 523 polymorphic sites in 104 strains.(2)molecular tracing of anthrax in camellia oleipes.From the perspective of camellia oleifera varieties nationwide,leaf DNA has a significant genealogical geographical structure,and the phylogenetic tree constructed by the maximum likelihood method(ML)has 8 branches with high support,which have an obvious geographical distribution pattern.The development direction of camellia oleaginous is divided into two directions.One is the local strain of wuzhishan in hainan,which is not crossed or grafted with other strains.The other direction is zhejiang→fujian→jiangxi→hubei → henan→hunan → yunnan guizhou.The development direction of the strain is fujian→jiangxi clones→hubei oil→long forest→hunan forest.Changlin series and xianglin series are the most advantageous oil tea series in China.(3)study on coevolution of anthrax strains of camellia oleifera and camellia oleifera.The growth rate and sporulation amount of different anthrax strains of camellia oleracea were significantly different under the same experimental conditions.Colletotrichum fructicola is the germ type with the largest coverage area at present.The provinces where samples were collected were mainly cloud,guizhou,hunan,hebei,zhejiang,jiangxi,fujian and guangdong.The separation rate reached 63.11%,which was the highest among the six anthrax bacteria.Colletotrichum siamense is also widely distributed in many provinces,mainly including jiang,zhe,xiang,min,GUI,ji and yun,with a separation rate of 11.54%.Colletotrichum aeschynomenes was isolated from two strains in zhejiang and jiangxi,with a small number and a 1.92%isolation rate.Colletotrichum gloeosporioides only appeared in henan province,China,with a separation rate of 0.96%.Colletotrichum camelliae was distributed in guizhou,fujian and yunnan,and the separation rate was about 4.81%.The first Colletotrichum sp.(1 plant)was from henan province.13 strains were suspected to be new strains,respectively from hainan,jiangxi and zhejiang,with a separation rate of 12.50%,indicating that different anthrax genera had certain preference to different oil tea strains.With the spread of anthrax strains,the haplotype quantity and richness of different anthrax strains in different provinces changed,which proved the coevolutionary relationship between anthrax strains and anthrax strains. |
