del Campo Raquel, Russi Paola, Mara Pamela, Mara Héctor, Peyrou Mercedes, de León Inés Ponce, Gaggero Carina
Departamento de Biología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay.
FEMS Microbiol Lett. 2009 Sep;298(2):143-8. doi: 10.1111/j.1574-6968.2009.01709.x. Epub 2009 Jun 26.
The most severe form of citrus canker disease is caused by Xanthomonas axonopodis pv. citri (Xac) and affects all types of important citrus crops, reducing fruit yield and quality. Copper-based products are routinely used as a standard control measure for citrus canker. In this work we demonstrate that copper treatment induces the viable but nonculturable (VBNC) state in Xac but does not prevent the development of symptoms in susceptible plants. Short-term exposures to different concentrations of copper solutions were assayed to determine which treatment resulted in Xac nonculturability. Treatment of 10(6) mL(-1) Xac cells for 10 min in a 135-muM CuSO(4) solution (equivalent to three times the free soluble copper concentration applied in one field treatment) resulted in nonculturability. However, 16% of cells were viable based on 5-cyano-2,3-ditolyl tetrazolium chloride staining and 1% were capable of producing canker lesions after infiltrating grapefruit plants. If induction of the VBNC state in Xac cells were to occur under field conditions, this would have to be taken into consideration for an effective control of canker disease.
柑橘溃疡病最严重的形式是由柑桔溃疡病菌（Xanthomonas axonopodis pv. citri，Xac）引起的，它会影响所有重要的柑橘类作物品种，降低果实产量和品质。铜基产品通常被用作柑橘溃疡病的标准防治措施。在这项研究中，我们证明铜处理可诱导Xac进入活的非可培养（VBNC）状态，但不能阻止感病植物出现症状。我们检测了Xac在不同浓度铜溶液中的短期暴露情况，以确定哪种处理会导致Xac不可培养。将10(6) mL(-1) 的Xac细胞在135 μM的CuSO(4) 溶液（相当于田间一次处理中施用的游离可溶性铜浓度的三倍）中处理10分钟后，Xac变得不可培养。然而，基于氯化-5-氰基-2,3-二苯基四氮唑染色，16%的细胞仍存活，并且在将其接种到葡萄柚植株后，1%的细胞能够产生溃疡病斑。如果在田间条件下Xac细胞会诱导进入VBNC状态，那么在有效防治溃疡病时必须考虑这一点。
