Deciphering the Bacterial Microbiome of Citrus Plants in Response to ‘Candidatus Liberibacter asiaticus’-Infection and Antibiotic Treatments

Abstract

The bacterial microbiomes of citrus plants were characterized in response to ‘Candidatus Liberibacter asiaticus’ (Las)-infection and treatments with ampicillin (Amp) and gentamicin (Gm) by Phylochip-based metagenomics. The results revealed that 7,407 of over 50,000 known Operational Taxonomic Units (OTUs) in 53 phyla were detected in citrus leaf midribs using the PhyloChip™ G3 array, of which five phyla were dominant, Proteobacteria (38.7%), Firmicutes (29.0%), Actinobacteria (16.1%), Bacteroidetes (6.2%) and Cyanobacteria (2.3%). The OTU62806, representing ‘Candidatus Liberibacter’, was present with a high titer in the plants graft-inoculated with Las-infected scions treated with Gm at 100 mg/L and in the water-treated control (CK1). However, the Las bacterium was not detected in the plants graft-inoculated with Las-infected scions treated with Amp at 1.0 g/L or in plants graft-inoculated with Las-free scions (CK2). The PhyloChip array demonstrated that more OTUs, at a higher abundance, were detected in the Gm-treated plants than in the other treatment and the controls. Pairwise comparisons indicated that 23 OTUs from the Achromobacter spp. and 12 OTUs from the Methylobacterium spp. were more abundant in CK2 and CK1, respectively. Ten abundant OTUs from the Stenotrophomonas spp. were detected only in the Amp-treatment. These results provide new insights into microbial communities that may be associated with the progression of citrus huanglongbing (HLB) and the potential effects of antibiotics on the disease and microbial ecology.

Zinc treatment increases the titre of ‘CandidatusLiberibacter asiaticus’ in huanglongbing-affected citrus plants while affecting the bacterial microbiomes

“…; Zhang et al . ) to test for the presence of Las bacterium. Both healthy and diseased potted plants were exposed to supplemental zinc using a soil drench.…”

“…; Zhang et al . ) and total DNA (100 ng) as the template. For data comparison across real‐time plates, the minimum threshold was set to 100 with drift correction selected.…”

“…; Zhang et al . ,b), to the best of our knowledge, there are no reports on the effects of zinc application on the microbial community in plants. Thus, in addition to evaluating the effect zinc has on HLB‐associated symptoms and Las populations, we will analyse how the citrus leaf microbiome is influenced by zinc amendments.…”

Defining the Core Citrus Leaf- and Root-Associated Microbiota: Factors Associated with Community Structure and Implications for Managing Huanglongbing (Citrus Greening) Disease

“…The severity of HLB is underscored by the billions of dollars in economic damage and thousands of jobs lost throughout Florida, where L. asiaticus is widespread, that occurred during the first few years of its documented emergence (35). Interestingly, clone library sequencing and PhyloChip surveys have shown citrus-associated microbiota restructure during HLB symptom development, and it has been suggested that the population dynamics of native bacteria can affect the titer of L. asiaticus (17,(36)(37)(38). In the present study, the microbial communities of citrus trees were defined across a number of variables, including HLB symptom severity, geographic location, citrus cultivar, season, and time.…”

LC-MS/MS Method for the Determination and Quantitation of Penicillin G and Its Metabolites in Citrus Fruits Affected by Huanglongbing

“…11,12 For example, Bove et al reported the effectiveness of penicillin G, 1 (Figure 1), and tetracycline injections for the treatment of infected sweet orange trees. 13 In another paper, Chung and Zhisheng studied the effectiveness of various antibiotic application methods.…”