The phytopathogenic mollicute-insect vector interface: a closer look

Area of Science:

• Plant pathology
• Insect microbiology
• Molecular biology

Background:

• Spiroplasma citri is a phytopathogenic mollicute transmitted by leafhoppers.
• Transmission involves the pathogen moving through insect tissues and barriers.

Purpose of the Study:

• To investigate the molecular basis of Spiroplasma citri transmission.
• To identify factors enabling Spiroplasma citri to cross insect barriers.

Main Methods:

• Comparative molecular analysis of transmissible and nontransmissible Spiroplasma citri lines.
• Identification and characterization of chromosomal rearrangements.
• Cloning and analysis of a specific open reading frame encoding a membrane protein.
• In vitro adhesion assays using cultured leafhopper cells and protease treatment.

Main Results:

• Transmissible Spiroplasma citri lines possess chromosomal rearrangements, including inversions and deletions, absent in nontransmissible lines.
• A deleted region in transmissible strains contains an open reading frame encoding a 58 kDa integral membrane protein.
• This protein shows similarity to adhesins of zoopathogenic mycoplasmas.
• Spiroplasma adhesion to leafhopper cells is mediated by membrane proteins and inhibited by proteases.

Conclusions:

• Chromosomal rearrangements are associated with Spiroplasma citri transmissibility.
• A specific membrane protein likely plays a key role in Spiroplasma adherence to and crossing of insect host barriers.
• This research contributes to understanding phytopathogenic mollicute transmission mechanisms.