Citrus Greening Research Project
Currently the citrus industry in Florida is facing the most devastating citrus disease that it has ever experienced, called citrus greening, also known as Huanglongbing disease (HLB). The disease has resulted in the decline and/or death of millions of citrus trees in Florida alone. HLB is caused by the phloem-limited insect-transmitted bacteria Candidatous liberobacter asiaticous (cLas). cLas virulence mechanisms are associated with phloem blockage, hormone imbalance, nutrient and carbon metabolism unbalances, as well as salicylic acid cascade disturbances. The disease symptoms include severe chlorosis, defoliation, fruit drop, seed abortion, and changes in the quality of the juice.
Pathway’s lab is part of the solution to HLB disease, by providing a technology that may result in the recovery from HLB symptoms in trees that are treated with our inoculants. A large-scale field evaluation is currently underway in several commercial groves in Florida, and the collection and analysis of data is being carried out testing Pathway’s technology against HLB. The variables measured in order to validate the effectiveness of Pathway’s technology on disease development include: disease severity, nutritional status of the plant, bacterial concentration, yield, and juice quality.
Many plant pathogens (Pythium, Rhizoctonia solani, Fusarium spp., Xanthomonas spp. and Pseudomonas spp.) have a wide host range, a cosmopolitan distribution, and the capacity to cause tremendous economic damage. Biological control using specific PGPR strains has been demonstrated against these pathogens. Typical biocontrol studies evaluate a single PGPR strain against a single pathogen (Murphy et al., 2003; Zhang et al., 2010). However, a single PGPR strain as biological control may suppress a narrow range of pathogens, and exhibit inconsistent performance in practical environment. Compared with single PGPR, mixtures of PGPR could manage multiple plant diseases that often occur in the field ((Domenech et al., 2006; Jetiyanon et al., 2003; Jetiyanon and Kloepper, 2002). Meanwhile, some biological PGPR agents can promote plant growth.
As part of Pathway’s ongoing research and screening within our collection, we perform antibiosis work with both single strain and PGPR polymicrobial groups. The overall objective is to form and assess our collection of PGPR for biocontrol of multiple plant diseases and plant growth promotion.
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