Microanatomy conformation of apple branch tumors caused by Botryosphaeria dothidea
Microanatomy conformation of apple branch tumors caused by Botryosphaeria dothidea
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发表时间：
2011
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通讯作者：
Guo Liyun
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作者：
Guo Liyun
以3 ~ 5个月大的富士苹果枝条为菌丝或分生孢子进行接种。从接种的和自然患病的树枝上取样皮孔或肿瘤周围的树皮。采用冷冻切片法对标本进行显微解剖，切片检查肿瘤的显微解剖构象。观察结果表明，接种30 d后，在枝条皮孔下方可发现新形成的肿瘤。菌丝从皮孔开始呈放射状生长和扩张，肿瘤菌丝粗壮，末端呈圆形或截形。肿瘤的所有菌丝都被几层被埋没的宿主细胞包围。被埋没的细胞伸展开来，排列成环状并包围菌丝。在肿瘤发展后期，可在肿瘤周围发现一层由几层被潜伏的宿主细胞组成的由表皮细胞扩增而成的亚粘液层。结果表明，双歧杆菌感染可促进寄主韧皮部新细胞的产生和细胞的分裂。新产生的细胞与菌丝一起形成肿瘤。亚毒层使肿瘤组织与健康宿主细胞分离，导致肿瘤及周围组织坏死。然后将坏死肿瘤的边缘抬起，就像下一年的马鞍一样，最终剥落。结果表明，肿瘤的形成和剥落是宿主对病原菌防御反应的结果。
Three to five months old Fuji apple branches were inoculated with conidia or mycelium of Botryosphaeria dothidea.Barks were sampled around lenticels or tumors from the inoculated and naturally diseased branches.The samples were cut with freezing microtomy and microanatomy conformations of tumors were examined with the microtome-sections.Observation results showed that newly formed tumors could be found just under lenticels from the branches 30 days after inoculation.The mycelia grew and expanded radially from the lenticels and the hyphae in tumors were thick and strong with circular or truncated end.All hyphae in deve-loped tumors were surround with several layers suberized host cells.The suberized cells stretched out,arranged in rings and enclosed the hyphae.A suberous layer,constructed of several layers of suberized host cells and expanded from epidermal cells,could be found just around the tumor in later stage of tumor development.The results suggested that B.dothidea infection stimulated the production of new host phloem cells and the cell suberization.The new produced cells together with the mycelia formed the tumors.The suberous layer separated the tumor tissue from health host cell and resulted in necrosis of tumor and surrounded tissues.The edge of the necrotic tumor was then lift,like saddle next year and finally peeled off.The observation suggested that tumor forming and peeling were the results of host defending reaction to the pathogen.