بررسي اهميت تغييرات ديواره اي سلولهاي مزوفيل در مقاومت به باكتري هاي غيربيماريزا

In peppers, inhibition of hrp mutant cells of Xanthomonas campestris pv. vesicatoria (Xcv) within leaf intercellular spaces is associated with alterations of mesophyll cell wall and papilla deposition. Immunocytochemical and histochemical tests on the responding cells indicated that lignification occurred in the altered walls. The papillae also contained substantial amounts of lignin in addition to autofluorescent phenolics and callose. Their progressive enlargement was associated with accumulation of hydrogen peroxide. Data on recovery of hrp mutant cells from inoculated leaves indicated that the bacteria not only failed to multiply, in plania but they also induced a bactericidal status in which the virulent Xev cells failed to multiply. As a result, water-soaking symptom was prevented. The inhibition of the virulent cells was neither related to a secreted compound nor nutrient shortage. Observations on mesophyll cell reactions to a number of saprophytic and non-pathogenic bacteria showed the occurrence of similar structural alterations at interaction sites. It is suggested that the prime cause for non-pathogenicity of the examined bacteria was activation of non-specific defensive structures rather than their disability to survive within leaf intercellular spaces.