Identification Of The Pathogen Of Bayberry Wilt And Screening Of Control Agent

Bayberry is an important cash crop that is widely cultivated in the southern region of China.Bayberry blight is mainly harmful to bayberry leaves,when invaded,the branches and leaves are first acutely green,and then gradually turn yellow,and brown until they die,the leaves do not fall off when the symptoms first appear,and the leaves gradually begin to fall off after 1-2 months.Severe symptoms can cause the entire tree to die.Bayberry leaves with typical blight symptoms were collected in Wencheng County,Zhejiang Province.By amplification and sequencing of the internal transcription spacer(ITS),translation elongation factor 1-α(EF1-α),and β-tubulin(β-TUB)genes,combined with morphological identification,the pathogen causing the symptoms was determined to be Pestalotiopsis.kenyana.In this study,the pathogenicity(reinfection,isolation,identification)of the fungus was determined by Koch’s rule.To our knowledge,this is the first time that P.kenyana has been reported to trigger symptoms of bayberry leaf wilt.To explore the biological characteristics of this strain and explore the application strategies in future field management of bayberry,we studied the effects of this strain on the growth of mycelium on the utilization of different carbon and nitrogen sources,temperature,light,p H,and type of culture medium.The results showed that peptone and soluble starch were the most suitable nitrogen and carbon sources,respectively.The optimal temperature for the growth of strain hyphae is 25°C;This strain was insensitive to light conditions,and there was no significant difference in the growth rate of hyphae under the three light hours.This strain prefers weak acidity.Finally,in this study,we determined the inhibitory activity of four biogenic pesticides against Pestalotiopsis kenyana.The results showed that PCA had the best inhibitory activity against pathogenic bacteria,and its EC50 was 0.83±0.14 μg/ml.The mechanism of action of PCA was preliminarily explored by transcriptomics technology combined with biochemistry and morphology.The results showed that after the treatment of these two agents,3613 differential genes were found,respectively,and most of the differentially expressed genes were concentrated in redox processes and various metabolic pathways.In addition,it can also cause mycelial development malformation,damage cell membranes,reduce mitochondrial membrane potential,increase reactive oxygen species levels,and reduce catalase and superoxide dismutase activity.In this study,the biological characteristics of bayberry blight pathogen bacteria and the screening of effective biopesticides are expected to be used in the field prevention and control of this symptom to help the development of the bayberry industry.