Dong Xiang-Li, Cheng Zi-Zhen, Leng Wei-Feng, Li Bao-Hua, Xu Xiang-Ming, Lian Sen, Wang Cai-Xia
College of Plant Health and Medicine, Qingdao Agricultural University; Key Lab of Integrated Crop Pests Management of Shandong Province, Qingdao, Shandong 266109, P.R. China.
NIAB EMR, East Malling, West Malling, Kent, ME19 6BJ, United Kingdom.
Phytopathology. 2021 Sep;111(9):1551-1559. doi: 10.1094/PHYTO-12-20-0551-R. Epub 2021 Oct 20.
Until recently, the causal agent of Botryosphaeria canker was assumed to differ from that causing ring rot on fruit and warts on branches on apple trees in China and East Asia. However, recent research documented that caused both disease symptoms on apple. Inoculations with strains isolated from cankers and warts on branches were conducted to investigate symptom progression caused by and conditions inducing the two symptom types. The results confirmed that both cankers and warts are caused by Warts are the results of hyperplasia and suberization of bark tissues induced by fungal infection, whereas cankers result from the rapid growth of hyphae from inside warts, lenticels, or wounds. Resistance to exists in living apple branches. When a living branch is infected via lenticels, the pathogen induces proliferation and suberization of cortical cells that restricts the growth and expansion of the hyphae, leading to warts. However, under certain stress conditions such as drought, the hyphae inside host tissues expand rapidly and kill cortical cells, leading to canker development. Host resistance may recover during active growth periods, which suppresses or even stops rapid expansion of the hyphae, leading to the intermediate symptom of canker warts. Abiotic factors, such as drought or high temperature in early spring, can result in rapid extension of colonized hyphae in branches and conversion of warts to cankers. Preventing this transition can be an important measure in managing Botryosphaeria canker on apple.
直到最近，人们一直认为苹果轮纹病菌的致病因子与在中国和东亚导致苹果果实轮纹病和枝条上瘤状物的致病因子不同。然而，最近的研究表明，该病菌会引发苹果的这两种病害症状。为了研究该病菌引发的症状进展情况以及诱发这两种症状类型的条件，对从溃疡病斑和枝条瘤状物中分离出的菌株进行了接种试验。结果证实，溃疡病斑和瘤状物均由该病菌引起。瘤状物是真菌感染诱导树皮组织增生和栓化的结果，而溃疡病斑则是病菌从瘤状物内部、皮孔或伤口处快速生长的菌丝所致。苹果的活枝条中存在对该病菌的抗性。当活枝条通过皮孔被感染时，病原菌会诱导皮层细胞增殖和栓化，从而限制菌丝的生长和扩展，导致瘤状物的形成。然而，在诸如干旱等特定胁迫条件下，寄主组织内的菌丝会迅速扩展并杀死皮层细胞，进而导致溃疡病斑的形成。在活跃生长阶段，寄主抗性可能会恢复，这会抑制甚至阻止菌丝的快速扩展，从而导致溃疡病瘤这种中间症状的出现。非生物因素，如早春的干旱或高温，会导致枝条中已定殖菌丝的快速扩展，并使瘤状物转变为溃疡病斑。防止这种转变可能是防治苹果轮纹病菌溃疡病的一项重要措施。
