Poplawsky A R, Urban S C, Chun W
Plant Pathology, Division, Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, Idaho 83844-2339, USA.
Appl Environ Microbiol. 2000 Dec;66(12):5123-7. doi: 10.1128/AEM.66.12.5123-5127.2000.
Previous studies have indicated that the yellow pigments (xanthomonadins) produced by phytopathogenic Xanthomonas bacteria are unimportant during pathogenesis but may be important for protection against photobiological damage. We used a Xanthomonas campestris pv. campestris parent strain, single-site transposon insertion mutant strains, and chromosomally restored mutant strains to define the biological role of xanthomonadins. Although xanthomonadin mutant strains were comparable to the parent strain for survival when exposed to UV light; after their exposure to the photosensitizer toluidine blue and visible light, survival was greatly reduced. Chromosomally restored mutant strains were completely restored for survival in these conditions. Likewise, epiphytic survival of a xanthomonadin mutant strain was greatly reduced in conditions of high light intensity, whereas a chromosomally restored mutant strain was comparable to the parent strain for epiphytic survival. These results are discussed with respect to previous results, and a model for epiphytic survival of X. campestris pv. campestris is presented.
先前的研究表明，植物病原黄单胞菌产生的黄色色素（黄单胞菌素）在致病过程中并不重要，但可能对抵御光生物学损伤很重要。我们使用野油菜黄单胞菌野油菜致病变种的亲本菌株、单位点转座子插入突变菌株和染色体修复突变菌株来确定黄单胞菌素的生物学作用。尽管黄单胞菌素突变菌株在暴露于紫外光时的存活情况与亲本菌株相当；但在暴露于光敏剂甲苯胺蓝和可见光后，其存活率大大降低。染色体修复突变菌株在这些条件下的存活率完全恢复。同样，在高光强度条件下，黄单胞菌素突变菌株的附生存活率大大降低，而染色体修复突变菌株的附生存活率与亲本菌株相当。结合先前的结果对这些结果进行了讨论，并提出了野油菜黄单胞菌野油菜致病变种附生存活的模型。
