NEW BNYVV P25 VARIANTS IN BELGIUM

Area of Science:

• Plant Pathology
• Virology
• Agricultural Science

Background:

• Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV), significantly impacts sugar beet production.
• BNYVV is transmitted by Polymyxa betae, a soil-borne vector that also carries Beet virus Q (BVQ) and Beet soil-borne virus (BSBV).
• Resistance genes in sugar beet are challenged by BNYVV's ability to evolve and its long survival in soil.

Purpose of the Study:

• To investigate the occurrence of resistance-breaking BNYVV strains in Belgium.
• To identify the specific BNYVV types and genetic motifs associated with resistance breakdown in sugar beet.

Main Methods:

• Multiplex RT-PCR was used to detect BNYVV, BSBV, BVQ, and P. betae in sugar beet root hairs.
• RT-PCR targeting P26 and P25 genes was employed to detect BNYVV RNA5 and RNA3.
• Partial cDNA sequences of the BNYVV P25 gene were sequenced to identify genetic variations.

Main Results:

• P. betae, BSBV, and BVQ were detected in all sampled fields.
• BNYVV was present in nine out of ten fields surveyed.
• Sequencing revealed BNYVV types A and B, with two isolates exhibiting the AYPR amino acid motif linked to resistance-breaking.

Conclusions:

• The study confirms the presence of resistance-breaking BNYVV strains in Belgian sugar beet fields.
• The identified genetic motifs provide evidence for the molecular basis of BNYVV resistance breakdown.
• Findings highlight the ongoing threat of BNYVV to sugar beet cultivation and the need for continued monitoring.