Nanobioscience Group, Agharkar Research Institute, G. G. Agarkar Road, Pune, Maharashtra, 411 004, India.
Savitribai Phule Pune University, Ganeshkind Road, Pune, Maharashtra, 411 007, India.
Appl Microbiol Biotechnol. 2019 Jun;103(11):4605-4621. doi: 10.1007/s00253-019-09740-z. Epub 2019 Apr 16.
Bacterial blight, caused by Xanthomonas axonopodis pv. punicae, Xap is a serious threat to commercially successful pomegranate (Punica granatum L) crop. Owing to the non-availability of disease-resistant varieties of pomegranate, integrated disease management involving change of season, adequate nutrition, and preventive sprays of bactericides is used to control Xap. We undertook a systematic study to assess the efficacy of metal-based nanomaterials (Cu, CuO, ZnO, CaO, MgO) for the control of Xap. The antimicrobial effectiveness was in the order Cu > ZnO > MgO > CuO with MIC (minimum inhibitory concentration) 2.5, 20, 190, 200, and 1600 μg/ml. A time-to-kill curve indicated that Cu nanoparticles (CuNPs) killed Xap cells within 30 min at 2.5 μg/ml. Under controlled conditions (polyhouse), foliar application of CuNPs (400 μg/ml) resulted in ~ 90 and ~ 15% disease reduction in 6-month-old infected plants at early (disease severity 10%) and established (disease severity 40%) stages of infection, respectively. In a subsequent field study on severely infected 7-year-old plants, applications of nanoparticles reduced the disease incidence by ~ 20% as compared to untreated control. Microscopic observations revealed that CuNPs reduced the bacterial colonization of the leaf surface. Anti-Xap activity of foliar applied CuNPs was on par with conventionally used copper oxychloride (3000 μg/ml) albeit at 8-fold reduced copper concentration. Thus, early disease detection and application of effective dosage of copper nanoparticles can indeed help the farmer in achieving rapid infection control. Further studies on use of combinations of nanoparticles for management of bacterial blight are warranted.
细菌性黑斑病，由黄单胞菌属 axonopodis pv。punicae，Xap 是对商业上成功的石榴（Punica granatum L）作物的严重威胁。由于缺乏石榴的抗病品种，综合疾病管理包括改变季节、充足的营养和预防性杀菌剂喷雾用于控制 Xap。我们进行了一项系统研究，评估金属基纳米材料（Cu、CuO、ZnO、CaO、MgO）对控制 Xap 的效果。抗菌效果的顺序为 Cu>ZnO>MgO>CuO，最小抑菌浓度（MIC）分别为 2.5、20、190、200 和 1600μg/ml。杀菌曲线表明，Cu 纳米粒子（CuNPs）在 2.5μg/ml 时在 30 分钟内杀死 Xap 细胞。在受控条件（温室）下，叶面喷施 CuNPs（400μg/ml）可使 6 个月大的感染植物在早期（疾病严重程度 10%）和晚期（疾病严重程度 40%）分别减少约 90%和 15%的疾病。在随后对严重感染的 7 年生植物进行的田间研究中，与未处理的对照相比，纳米粒子的应用使发病率降低了约 20%。显微镜观察表明，CuNPs 减少了叶表面的细菌定植。叶面喷施 CuNPs 的抗 Xap 活性与常规使用的氧氯化铜（3000μg/ml）相当，尽管铜浓度降低了 8 倍。因此，早期发现疾病并应用有效剂量的铜纳米粒子确实可以帮助农民实现快速的感染控制。需要进一步研究纳米粒子组合在细菌性黑斑病管理中的应用。
