中文摘要：

接种褐斑病菌分生孢子悬浮液于山定子与富士苹果叶片，接种后1、3d和5d取样，提取DNA，检测DNA ladder；提取样品粗蛋白，用特异性荧光底物检测粗蛋白中类caspase活性，探索山定子受褐斑病菌侵染过程中引起的细胞程序性死亡（PCD ）与抗性的关系，检测DNA ladder和类caspases活性变化的规律。研究发现：在接种后1、3 d和5 d ，山定子和富士苹果叶片中没有明显DNA ladder的产生；受检测的YVADase、DEVDase、IETDase和VEI-Dase活性在接种后1 d和3 d没有显著变化，但在接种后5 d ，活性均降低30％左右，显著低于对照。研究表明，山定子在褐斑病菌侵染过程中并没有DNA ladder产生，但却伴随着类caspase活性的下降。

英文摘要：

Detached leaves of Malus baccata and Malus domestica cv .Fuji were inoculated with conidia suspension of Diplocarpon mali .Samples were harvested one day after inoculation （dai） ,3 dai and 5 dai ,respectively .DNA of the samples was extracted for detection of DNA ladder .Gross proteins of the samples were extracted for detection of caspase-like activities using special fluorescent substrate .DNA ladder and caspase-like activities were examined to explain the re-lationship between programmed cell death （PCD ） and resistance of M . baccata infected by D . mali . The results showed that DNA ladder was barely detected in M . baccata 1 dai ,3 dai or 5 dai .Activities of YVADase ,DEVDase ,I-ETDase and VEIDase in leaves of M . baccata were shown to have no variations 1 dai and 3 dai ,while became decreased 5 dai to about 30% of those 1 dai ,which was significantly lower than those of the control group .This study showed that DNA ladder was not generated in M . baccata during the infection of D . mali with the accompany of declining caspase-like activities .