Spatiotemporal separation of groundnut rosette disease agents

Area of Science:

• Plant Virology
• Entomology
• Agricultural Science

Background:

• Groundnut rosette disease (GRD) is a major threat to groundnut production in Africa.
• GRD is caused by a complex of viruses, including groundnut rosette virus (GRV), its satellite RNA (sat RNA), and groundnut rosette assistor virus (GRAV).
• The transmission dynamics of these agents by the aphid vector Aphis craccivora are not fully understood.

Purpose of the Study:

• To investigate the transmission patterns of GRAV, GRV, and sat RNA by Aphis craccivora.
• To determine if the agents are transmitted simultaneously or separately during aphid feeding.
• To correlate the presence of agents in aphids with their transmission to groundnut plants.

Main Methods:

• Triple-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for virus detection in plants.
• Viruliferous Aphis craccivora collected from fields were used for transmission studies.
• Electrical penetration graph (EPG) to monitor aphid feeding behavior.
• Reverse-transcriptase polymerase chain reaction (RT-PCR) for agent detection in aphids and plants.

Main Results:

• GRAV was detected in some symptomatic and symptomless groundnut plants, and also in symptomless plants.
• Aphis craccivora transmitted GRAV alone, GRV with sat RNA, or all three agents, with varying proportions.
• EPG studies showed GRV and sat RNA transmitted during stylet pathway and salivation phases, while GRAV was transmitted only during salivation.
• Simultaneous transmission of all three agents occurred only during the salivation phase.
• RT-PCR revealed no correlation between the presence of all three agents in aphids and their simultaneous transmission.

Conclusions:

• The agents causing groundnut rosette disease can separate during transmission by Aphis craccivora.
• Transmission efficiency and patterns differ among GRAV, GRV, and sat RNA.
• Aphid feeding behavior, specifically salivation, plays a critical role in the transmission of these agents.
• Understanding these transmission dynamics is crucial for managing groundnut rosette disease.