桃拟茎点霉的侵染过程及其致病影响因子研究

Study on the infection process and pathogenic influencing factors of Phomopsis amygdali

[目的]桃枝枯病严重威胁着我国南方桃产业的发展,南方桃园中桃拟茎点霉(Phomopsis amygdali)属于桃枝枯病菌流行优势种,但其侵染过程及致病影响因子目前尚不清楚。因此,本文旨在探究P.amygdali侵染过程及其致病影响因子。[方法]探究桃拟茎点霉分生孢子的萌发过程,运用扫描电镜观察不同时间点分生孢子侵染桃嫩枝的部位,并在不同温度、湿度、光照时间的处理下探究该菌致病力的强弱,进一步运用商品化壳梭孢素对其进行毒力测定。[结果]桃拟茎点霉的甲型分生孢子在PDA固体培养基上培养3 h萌发率为66.4%,9 h后分生孢子萌发率为97.6%,24 h后分生孢子产生单根较长的芽管,30 h后菌丝产生隔膜,36 h后产生有分支的营养菌丝。扫描电镜结果显示,侵染菌丝主要入侵桃嫩枝木质部导管及中央髓部,并且破坏木质部导管的结构,然而,在韧皮部并没有观察到侵染菌丝的存在。温度和相对湿度是影响桃拟茎点霉致病力的主要因子,且病害流行的最适温度为30℃,最适相对湿度为98%。桃拟茎点霉产生的壳梭孢素是其致病因子。[结论]本文首次探究了桃拟茎点霉的侵染过程,并发现温度和相对湿度是影响该菌致病力的主要环境因子。

[Objectives]Peach shoot blight(PSB)greatly influenced the development of peach industry,Phomopsis amygdali which caused PSB was the most prevalent pathogens in peach orchard at south China.However,the infection process and pathogenic influencing factors remain unclear.Therefore,this study aimed to explore the infection process of P.amygdali and its pathogenic influencing factors.[Methods]In this work,conidial germination of P.amygdali and infection sites were observed through scanning electron microscopy(SEM).Different environmental conditions were used to explore pathogenic influencing factors of P.amgdali.Commercial fusicoccin was used to measured its virulence effect.[Results]The germination rate ofα-conidia of P.amygdali was 66.4%at 3 hours post inoculation,97.6%at 9 h,then,single long germ tube produced at 24 h,septum formed at 30 h,and branching mycelium formed at 36 h.SEM observation showed that infective hyphae might mainly infect xylem and pith part of peach twigs,that destroyed the structure of xylem,and there were no infective hyphae at the phloem.Further,the study found that temperature and relative humidity(RH)were the main factors affecting the pathogenicity of P.amygdali.Among them,30℃and 98%RH were the best optimum temperature and relative humidity for the disease.Fusicoccin,one toxin produced by P.amygdali,was also one of pathogenic factors of P.amygdali.[Conclusions]In this work,the infection process of P.amygdali was investigated for the first time and the main environmental factors affecting its pathogenicity were temperature and RH.