Zolobowska Lena, Van Gijsegem Frédérique
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
Mol Plant Microbe Interact. 2006 Jun;19(6):597-606. doi: 10.1094/MPMI-19-0597.
Ralstonia solanacearum is a soilborne plant pathogen that invades its host via roots. As in many gram-negative bacterial plant pathogens, the R. solanacearum Hrp type III secretion system is essential for interactions of the bacterium with plants; however, the related mechanisms involved in disease expression are largely unknown. In this work, we examined the effects of infection by R. solanacearum GMI1000 and Hrp mutants on the root system of petunia plants. Both the wild-type and mutant strains disturbed the petunia root architecture development by inhibiting lateral root elongation and provoking swelling of the root tips. In addition, GMI100 but not the Hrp mutants induced the formation of new root lateral structures (RLS). This ability is shared by other, but not all, R. solanacearum strains tested. Like lateral roots, these new structures arise from divisions of pericycle founder cells which, nevertheless, exhibit an abnormal morphology. These RLS are efficient colonization sites allowing extensive bacterial multiplication. However, they are not required for the bacterial vascular invasion that leads to the systemic spread of the bacterium through the whole plant, indicating that, instead, they might play a role in the rhizosphere-related stages of the R. solanacearum life cycle.
青枯雷尔氏菌是一种土传植物病原体，可通过根部侵入宿主。与许多革兰氏阴性细菌植物病原体一样，青枯雷尔氏菌的Hrp III型分泌系统对于该细菌与植物的相互作用至关重要；然而，疾病表达所涉及的相关机制在很大程度上尚不清楚。在这项研究中，我们研究了青枯雷尔氏菌GMI1000及其Hrp突变体感染对矮牵牛植物根系的影响。野生型和突变体菌株均通过抑制侧根伸长和引发根尖肿胀来扰乱矮牵牛根系结构的发育。此外，GMI1000而非Hrp突变体诱导形成新的根侧结构（RLS）。其他一些（但并非全部）测试的青枯雷尔氏菌菌株也具有这种能力。与侧根一样，这些新结构源自中柱鞘起始细胞的分裂，不过，这些起始细胞呈现出异常的形态。这些RLS是有效的定殖位点，可使细菌大量繁殖。然而，细菌通过维管束侵入从而在整株植物中系统传播并不需要这些RLS，这表明，相反，它们可能在青枯雷尔氏菌生命周期中与根际相关的阶段发挥作用。
