苹果实生树枝干对轮纹病菌抗病性反应的差异

为进一步研究苹果枝干对轮纹病的抗病机理,以红玉×金冠杂种后代中表现不同抗病性的杂种实生树为试材,分析了不同抗病性的实生树枝条皮孔密度差异,接种轮纹病菌丝后枝条皮层木质素含量的变化,并采用扫描电镜技术,观察了接种点表面超微结构的变化。对20份不同抗性实生树1年生枝条皮孔密度的调查表明,在本分离群体内,皮孔密度与抗病性未见显著相关性。对苹果枝干轮纹病抗病、感病的杂种实生树进行接种,菌丝均可从皮孔侵入,但抗病的杂种实生树表现为致瘤性弱。接种病原后抗病和感病材料均会导致木质素含量的增加,但抗病材料木质素的增加量显著高于感病材料,表明木质素含量的激增与抗病性相关。金冠×红玉杂种后代中抗病单株的抗病性并非表现为抑制病原菌丝侵入,而表现为侵染后,通过诱导皮层木质素积累,抑制病原菌丝在寄主体内的扩展。

Different host/pathogen responses between Botryosphaeria dothidea and Malus domestica

This paper is concerned on the disease resistant mechanism of apple bot canker (Botryosphaeria dothidea (Moug.) Ces.et de Not.).The experiment was carried with utilization of the seedings derived from a hybrid population (Jonathan×Golden Delicious) with various disease resistance as test materials.The bark lenticel densities of branches were determined between different seedings.The changes of the lignin were monitored following infection of B.dothidea.The ultrastructural changes on the vaccination site was observed by scanning electron microscope.The bark lenticel density in 20 different seedings indicates that,in this segregating population,there was no significant correlation between bark lenticel density and bot canker disease index.Neither the resistant nor the susceptible apple stem was infected through lenticels by infection hyphae,but the tumorigenicity of the resistant ones was weak.Lignin content in all materials increased due to infection.The resistance materials had significant higher lignin content than that of the susceptible materials.The sharpincrease of lignin might be related to the host disease resistance.It was evident that the resistant performance in this hybrid(Jonathan×Golden Delicious) was not because of the curb to the pathogen invasion,but because of inducing in cortex lignin accumulation,and preventing the pathogen from expanding in the host.