Hao Lingyun, Zaini Paulo A, Hoch Harvey C, Burr Thomas J, Mowery Patricia
Section of Plant Pathology and Plant-Microbe Biology, SIPS, Cornell University-New York State Agricultural Experiment Station, Geneva, New York, United States of America.
Department of Biology, Hobart and William Smith Colleges, Geneva, New York, United States of America.
PLoS One. 2016 Aug 10;11(8):e0160978. doi: 10.1371/journal.pone.0160978. eCollection 2016.
Xylella fastidiosa is a xylem-limited bacterium in plant hosts and causes Pierce's disease (PD) of grapevines, which differ in susceptibility according to the Vitis species (spp.). In this work we compared X. fastidiosa biofilm formation and population dynamics when cultured in xylem saps from PD-susceptible and -resistant Vitis spp. under different conditions. Behaviors in a closed-culture system were compared to those in different sap-renewal cultures that would more closely mimic the physicochemical environment encountered in planta. Significant differences in biofilm formation and growth in saps from PD-susceptible and -resistant spp. were only observed using sap renewal culture. Compared to saps from susceptible V. vinifera, those from PD-resistant V. aestivalis supported lower titers of X. fastidiosa and less biofilm and V. champinii suppressed both growth and biofilm formation, behaviors which are correlated with disease susceptibility. Furthermore, in microfluidic chambers X. fastidiosa formed thick mature biofilm with three-dimensional (3-D) structures, such as pillars and mounds, in saps from all susceptible spp. In contrast, only small aggregates of various shapes were formed in saps from four out of five of the resistant spp.; sap from the resistant spp. V. mustangensis was an exception in that it also supported thick lawns of biofilm but not the above described 3-D structures typically seen in a mature biofilm from the susceptible saps. Our findings provide not only critical technical information for future bioassays, but also suggest further understanding of PD susceptibility.
木质部难养菌是一种在植物宿主中局限于木质部的细菌，可引发葡萄的皮尔氏病（PD），不同葡萄品种对该病的易感性存在差异。在本研究中，我们比较了木质部难养菌在不同条件下于感病和抗病葡萄品种的木质部汁液中培养时的生物膜形成及种群动态。将封闭培养系统中的行为与不同汁液更新培养中的行为进行了比较，后者更能模拟植物体内所遇到的物理化学环境。仅在汁液更新培养中观察到感病和抗病品种的汁液在生物膜形成和生长方面存在显著差异。与感病的酿酒葡萄的汁液相比，抗病的estivalis葡萄的汁液中木质部难养菌的滴度较低，生物膜较少，而champinii葡萄既抑制生长也抑制生物膜形成，这些行为与疾病易感性相关。此外，在微流控腔室中，木质部难养菌在所有感病品种的汁液中形成了具有三维（3-D）结构（如柱状和丘状）的厚成熟生物膜。相比之下，在五个抗病品种中的四个品种的汁液中仅形成了各种形状的小聚集体；抗病品种野马葡萄的汁液是个例外，它也支持形成厚的生物膜层，但没有易感品种汁液中成熟生物膜中常见的上述三维结构。我们的研究结果不仅为未来的生物测定提供了关键技术信息，还为进一步理解皮尔氏病的易感性提供了思路。
