Iris yellow spot virus in Onion in Chile

Area of Science:

• Plant Pathology
• Virology
• Agricultural Science

Background:

• Iris yellow spot virus (IYSV) is an endemic tospovirus affecting onion crops globally.
• IYSV has been reported in the United States and Brazil, indicating its spread in South America.

Purpose of the Study:

• To confirm the presence of IYSV in onion crops in central Chile.
• To characterize the IYSV strains detected in Chile.

Main Methods:

• Field surveys were conducted in onion-growing regions of central Chile (Colina, Tiltil, Rengo) during 2004-2005.
• Symptomatic plants exhibiting diamond-shaped chlorotic/necrotic lesions were tested using IYSV-specific ELISA and RT-PCR.
• Nucleoprotein (NP) gene sequences from five positive samples were amplified, cloned, sequenced, and compared to known IYSV strains.

Main Results:

• IYSV infection was confirmed in onion fields in Colina, Tiltil, and Rengo, with up to 50% of crops showing symptoms.
• Sequence analysis of the NP gene revealed 95-98% identity with known IYSV strains, confirming the virus identity.
• The presence of IYSV in Chile suggests its potential establishment in regional onion production.

Conclusions:

• IYSV is actively circulating in Chilean onion crops.
• The genetic similarity of Chilean IYSV isolates to other global strains indicates potential for widespread dissemination.
• Monitoring and management strategies are crucial for controlling IYSV in South American onion production.