Cotton leafroll dwarf virus was first detected in 2017 in a cotton field in Barbour County, Alabama, and since then has been detected in much of the cotton belt from Texas to the southeast. The sequence of CLRDV from Alabama (5,865 bases) was determined in 2020 with 94.8-95.2% of the genome matching six previously reported typical and atypical strains from Argentina and Brazil with seven open reading frames including the coat protein and the aphid transmission protein, P3 and P3-5. Transmission of CLRDV by A. gossypii has been shown and it is suspected to be persistent and non-propagative consistent with other Poleroviruses in the family Solemoviridae. Distorted leaves, leaf rugosity, upward or downward cupping of leaves, and stunting may be present in young plants, however, symptom expression can vary. Asymptomatic infections are also common. The virus is suspected to be phloem limited in plants and has a variable titer depending on the season. To better understand this system, an infectious clone of CLRDV was developed which shows no symptoms in cotton when grown in laboratory conditions. To better determine infection, a version of the clone was constructed replacing part of the P3-5 with GFP like Turnip yellows virus. To further study the function of the P3 protein, it was expressed in cotton plants fused to GFP and detected in aphids after feeding. Understanding the molecular function of the transmission cycle in CLRDV is the first step towards blocking movement of the virus in the fields.
.png)
