|ZHANG, MUQING - University Of Florida|
|GUO, YING - University Of Florida|
|POWELL, CHARLES - University Of Florida|
|YANG, CHUANYU - University Of Florida|
|ZHOU, HUI - Guangxi University|
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2016
Publication Date: 4/5/2016
Publication URL: http://handle.nal.usda.gov/10113/62831
Citation: Zhang, M., Guo, Y., Powell, C.A., Doud, M.S., Yang, C., Zhou, H., Duan, Y. 2016. Zinc treatment increases the titre of ‘Candidatus Liberibacter asiaticus’ in Huanglongbing-affected citrus plants while affecting the bacterial microbiomes. Journal of Applied Microbiology. 120:1616-1628. doi: 10.1111/jam.13102.
Interpretive Summary: Huanglongbing (HLB), also called citrus greening, is a disease in citrus cause by a bacterium called ‘Candidatus Liberibacter asiaticus’ (Las). Diseased trees often have discolored leaves that are similar to those caused by zinc deficiencies. Zinc is essential for both citrus and bacteria. In this study, we gave healthy and HLB citrus trees supplemental zinc at different amounts. We then determined if the amount of Las in the leave changed and how the disease symptoms were affected. The results showed that the supplemental zinc increased the amount of Las bacteria and did not reduce HLB disease symptoms. In addition, we examined the entire population of all bacteria that live within the citrus leaf and found that zinc shifts the population causing different bacteria to live within the leaf and in different amounts.
Technical Abstract: Huanglongbing (HLB)-affected citrus often display zinc deficiency symptoms. In this study, supplemental zinc was applied to citrus to determine its effect on Candidatus Liberibacter asiaticus (Las) titer, HLB symptoms, and leaf microbiome. HLB-affected citrus were treated with various amounts of zinc. The treatments promoted Las growth and affected microbiomes in citrus leaves. PhylochipTM-based results indicated that 5,475 of over 50,000 known Operational Taxonomic Units (OTUs) in 52 phyla were detected in the midribs of HLB-affected citrus, of which Proteobacteria was the most abundant, followed by Firmicutes and Actinobacteria. In comparison, the microbiomes of zinc-treated diseased plants had overall more OTUs with higher amounts of Proteobacteria, but decreased percentages of Firmicutes and Actinobacteria. In addition, more OTUs of siderophore-producing bacteria were present. Only zinc-sensitive Staphylococcaceae had higher OTU’s in the diseased plants without zinc treatments. Although HLB-affected citrus appear zinc deficient, zinc amendments increased the pathogen levels and shifted the microbiome. HLB is currently the most devastating disease of citrus worldwide. Zinc is often applied to HLB-affected citrus due to zinc deficiency symptoms. This study provided new insights into the potential effects of zinc on HLB and the microbial ecology of citrus.