Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849.
Department of Biological Sciences, Auburn University, Auburn, AL 36849.
Plant Dis. 2020 Mar;104(3):724-730. doi: 10.1094/PDIS-08-19-1748-RE. Epub 2020 Jan 21.
is a xylem-limited plant pathogenic bacterium that causes disease in many crops worldwide. Copper (Cu) is an antimicrobial agent widely used on hosts to control other diseases. Although the effects of Cu for control of foliar pathogens are well known, it is less studied on xylem-colonizing pathogens. Previous results from our group showed that low concentrations of CuSO increased biofilm formation, whereas high concentrations inhibited biofilm formation and growth in vitro. In this study, we conducted in planta experiments to determine the influence of Cu in infection using tobacco as a model. -infected and noninfected plants were watered with tap water or with water supplemented with 4 mM or 8 mM of CuSO. Symptom progression was assessed, and sap and leaf ionome analysis was performed by inductively coupled plasma with optical emission spectroscopy. Cu uptake was confirmed by increased concentrations of Cu in the sap of plants treated with CuSO-amended water. Leaf scorch symptoms in Cu-supplemented plants showed a trend toward more severe at later time points. Quantification of total and viable in planta indicated that CuSO-amended treatments did not inhibit but slightly increased the growth of . Cu in sap was in the range of concentrations that promote biofilm formation according to our previous in vitro study. Based on these results, we proposed that the plant Cu homeostasis machinery controls the level of Cu in the xylem, preventing it from becoming elevated to a level that would lead to bacterial inhibition.
是一种木质部局限型植物病原细菌，可导致全球许多作物发病。铜（Cu）是一种在宿主上广泛用于控制其他疾病的抗菌剂。尽管 Cu 控制叶部病原体的效果众所周知，但对木质部定殖病原体的研究较少。我们小组之前的结果表明，低浓度的 CuSO 会增加生物膜的形成，而高浓度则会抑制体外生物膜的形成和生长。在这项研究中，我们使用烟草作为模型进行了体内实验，以确定 Cu 对 感染的影响。用自来水或补充了 4 mM 或 8 mM 的 CuSO 的水给感染和未感染的植物浇水。通过电感耦合等离子体发射光谱法评估了症状的进展，并对汁液和叶片离子组进行了分析。Cu 的摄取通过用 CuSO 处理的植物汁液中 Cu 浓度的增加得到证实。补充 Cu 的植物中的叶片焦烧症状在后期表现出更严重的趋势。体内总和活菌数量的定量表明，CuSO 处理并没有抑制，而是轻微地增加了 的生长。根据我们之前的体外研究，汁液中的 Cu 处于促进生物膜形成的浓度范围内。基于这些结果，我们提出植物 Cu 稳态机制控制木质部中 Cu 的水平，防止其升高到导致细菌抑制的水平。
