Made for Each Other: Vector-Pathogen Interfaces in the Huanglongbing Pathosystem

Area of Science:

• Plant Pathology
• Entomology
• Microbiology

Background:

• Citrus greening (huanglongbing, HLB) is a devastating citrus disease.
• HLB is caused by 'Candidatus Liberibacter asiaticus', a phloem-restricted bacterium.
• The bacterium is transmitted by the Asian citrus psyllid, Diaphorina citri.

Purpose of the Study:

• To review the complex interactions between 'Ca. L. asiaticus' and its vector, D. citri.
• To understand molecular mechanisms of acquisition, circulation, and transmission of the pathogen.
• To explore the impact of the pathogen on the vector's physiology and fitness.

Main Methods:

• Review of existing molecular, biochemical, and biological studies.
• Analysis of pathogen acquisition, growth, and circulation within the insect vector.
• Examination of pathogen effects on vector metabolism, immunity, and reproduction.

Main Results:

• 'Ca. L. asiaticus' acquisition and circulation within D. citri are complex molecular processes.
• The pathogen significantly impacts D. citri's energy metabolism, immune system, and detoxification pathways.
• Despite negative effects, 'Ca. L. asiaticus' enhances D. citri's fitness, leading to higher fecundity and altered feeding behavior.

Conclusions:

• The relationship between 'Ca. L. asiaticus' and D. citri evolves towards mutualism.
• Understanding these interactions is crucial for developing novel HLB management strategies.
• Targeting vector-pathogen interactions may offer innovative control methods for citrus greening.