SGM Journals

Research explained · Plant virus transmission

Where do aphids pick up cauliflower mosaic virus?

Two aphid species picked up cauliflower mosaic virus most readily during sustained feeding from the phloem, the plant tissue that carries sugars. The researchers also recorded some acquisition after brief punctures in cells outside the phloem. [1]

See original studies View the SGM research record

How virus pickup changed as aphids fed

Before sustained feeding
Aphids sometimes acquired virus after briefly puncturing cells in tissues outside the phloem.
Successful pickup at this stage was uncommon in the study. [1]
During sustained phloem feeding
Acquisition became more likely when the aphids entered sustained ingestion from the phloem.
Acquisition rates were higher in this feeding stage than after brief punctures outside the phloem. [1]
Inside the phloem
In phloem cells called sieve elements, electron microscopy with antibody labels showed virus particles associated with the viral protein P3. The team did not detect the helper protein P2 there.
That difference in what the team could detect gave them a clue about when aphids might pick up the proteins. [1]

How could the researchers tell what an aphid was doing?

The researchers recorded electrical signals from the insects as their needle-like mouthparts moved and fed. The traces helped distinguish a quick puncture from sustained feeding in the phloem. The team then tested whether the aphids could pass the virus to another plant. [1]

What is the two-stage explanation?

The authors proposed that an aphid could pick up the helper protein P2 during a brief puncture and acquire virus particles later from the phloem. That sequence fits the feeding records and the distribution of the proteins. The investigators did not watch the two pickups in a single insect. [1]

Can the virus respond when an aphid arrives?

A separate live-cell study found that structures involved in cauliflower mosaic virus transmission reorganized rapidly in response to cues associated with the insect. That work measured a response to contact. The 2002 study measured where and when aphids acquired the virus. [1][2]

Original research

  1. Palacios et al. (2002), Journal of General Virology. Cauliflower mosaic virus is preferentially acquired from the phloem by its aphid vectors. Primary study using feeding traces, transmission tests and electron microscopy.
  2. Martinière et al. (2013), eLife. A virus responds instantly to the presence of the vector on the host and forms transmission morphs. Live-cell experiments on how transmission structures respond to vector-related cues.