Species Identification Of Botryosphaeriaceae From Blueberry Stem In Parts Of China

With the increase of planting area and yield of blueberries in China year by year,the diseases of blueberries have been paid more and more attention.So far,blueberry stem diseases have been widespread in blueberry producing areas around the world,which caused blueberry stem blight,xylem necrosis and plant death.The stem disease has been reported in China,and it has seriously affected the output and quality of blueberries in China.Among them,the botryosphaeriaceous fungi have been widely regarded as the main causal agents of blueberry stem diseases.Based on the phylogenetic analysis and morphological feature,pathogen and symptoms types,pathogenicity and culture conditions of blueberry stems diseases were studied.The following results have been gained:1.Blueberry stem diseases were surveyed and sampled in 8 blueberry gardens in six provinces in China during 2017 and 2018.A total of 500 blueberry stem disease samples were collected.After fungal isolation,DNA extraction and PCR amplification,a total of 443 strains of Botryosphaeriaceae(Botryosphaeria,Diplodia,Dothiorella,Macrophomina,Neofusicoccum,Lasiodiplodia)were collected.In this study,a total of 79 strains of the Botryosphaeriaceae were selected for further experiments.Based on the molecular characterization and morphological identification,the 79 strains of the Botryosphaeriaceae were classified into 3 genera and 10 novel species.The ten novel species were Lasiodiplodia vaccinii,Macrophomina vaccinii,Neofusicoccum vaccinii,N.highlandense,N.longiiconidium,N.yunnanicum,N.wuyangmaense,N.majiangense,N.ashei and N.lincangense.2.Pathogenicity tests indicated that Lasiodiplodia vaccinii,Macrophomina vaccinii,Neofusicoccum vaccinii,N.highlandense,and N.majiangense can cause twig blight on blueberry twigs,while N.longiiconidium,N.yunnanicum,N.wuyangmaense,N.ashei and N.lincangense can not cause twig blight on blueberry twigs.3.By testing the effects of different temperature,different p H,different carbon and nitrogen sources on the growth of mycelium,the culture characteristics of the representative strains of 10 species were studied.The results show that mycelia of Lasiodiplodia vaccinii,Macrophomina vaccinii,Neofusicoccum vaccinii,N.highlandense,N.longiiconidium,N.yunnanicum,N.wuyangmaense,N.majiangense,N.ashei and N.lincangense can be grown at temperatures ranging from 15 to 35 °C.And the optimum growth temperature of L.vaccinii,N.vaccinii,N.highlandense,N.longiiconidium,N.yunnanicum,N.wuyangmaense,N.majiangense,and N.ashei were 30 °C,while M.vaccinii and N.lincangense had the optimum growth temperatures of 35 °C and 25 °C respectively.The representative strains of the 10 species could all grow in the range of p H value of 3-9,but there was a certain difference in the optimal p H value.All the eight carbon and nitrogen sources tested could be utilized,but the utilization degree of different carbon and nitrogen sources was not consistent.The results indicated various species have different adaptation to temperature,p H and carbon and nitrogen source.