青枯菌对桉树及非寄主树木根部吸附和侵入的比较

通过接种青枯菌与非病原的大肠杆菌,对2个桉树无性系和1种非寄主树木的根表吸附菌量及根内含菌量进行测定.结果表明:青枯菌对感病寄主根表的吸附量多于对抗病寄主和非寄主根表的吸附量,对感病寄主根部的侵入量多于对抗病寄主但少于对非寄主根部的侵入量;病原菌较非病原菌对感病寄主根表的吸附量大,但二者对感病寄主根部的侵入量则依据根部伤口的有无而互有高低.青枯菌接种24 h内,感病寄主根表吸附菌量和根内含菌量呈上升趋势,在抗病寄主及非寄主根表的吸附菌量和根内含菌量却呈下降趋势.从统计学上看,青枯菌对寄主根部的吸附和侵入都显示出了一定的选择性,但由于病原细菌能够大量地吸附和侵入抗病寄主和非寄主根部,非病原细菌也能够大量地吸附和侵入桉树根部,因此这种选择性的生物学意义不大,青枯菌对桉树根表没有表现出明显的识别行为.

Comparison on Adsorption and Ingression of Ralstonia solanacearum to Eucalyptus and a Nonhost Tree

By measuring the number of bacteria adsorbed on root surfaces and contained in roots of 2 eucalyptus clones with different extent in resistance to the bacterial wilt and a non-host species after inoculation with Ralstonia solanacearum and non-pathogenic Escherichia coli,it was found that the number of adsorption of R. solanacearum to the root surface of susceptible host was greater than that of the resistant hosts and non-host, the number of ingression of the pathogen to the root of susceptible host was greater than that of the resistant hosts but smaller than that of the non-host; the number of adsorption of pathogenic bacteria to susceptible eucalyptus root surface was greater than that of the non-pathogenic bacteria, the number of ingression of the pathogen to susceptible host root was greater or smaller than that of the non-pathogen depending on whether there were wounds on roots. During a period of 24 h after inoculation, the number of R. solanacearum both adsorbed on root surface and contained in root exhibited an increasing tendency in susceptible eucalyptus but a decline pattern in resistant host and non-host. Statistically, R. solanacearum demonstrated a certain degree of selectivity in terms of adsorption and ingression to host root, the selectivity, however, was of little biological significance since the pathogenic bacteria could adsorb to and ingress into the roots of resistant host and non-host in a great quantity, and non-pathogenic bacteria could also adsorb to and ingress into the root of eucalyptus in a great number. R. solanacearum did not show an evident recognition behavior to the root surface of eucalyptus.