CLRDV-AL Encoded Suppressor of RNA Silencing and its Impact on Pathogenicity

Abstract

Cotton contributes to a broad range of industries like textile, food, and healthcare industries. However, it is prone to different pests and diseases. One such is the cotton blue disease caused by the Cotton leafroll dwarf virus (CLRDV). This virus caused about 80% yield loss in South America. A new strain (CLRDV-AL) was reported for the first time in the United States. CLRDV-AL contains a resistance-breaking amino acid motif, making available resistant cultivars inefficient for its management. This poses a huge risk to the US cotton industry. Therefore, the CLRDV-AL function and virulence mechanism need to be dissected to identify candidate-resistant genes for developing resistant cotton varieties. I aim to characterize the viral suppressor of RNA silencing encoded by CLRDV-AL and its distinction from P0 proteins from other strains (Objective 1). For this, I hypothesize that CLRDV-AL VSR protein has a weak silencing suppression potency. After this, I will evaluate the risk associated with CLRV-AL virulence by introducing point mutations to significant amino acid residues of P0 (Objective 2). Here I predict that a conserved F-box-like motif affects P0 pathogenicity. Hence, host-virus interaction. To achieve this, P0 proteins from three strains and mutant derivatives will be examined for VSR potency, host response, and intracellular localization. My results will provide key information about the role of P0 in the CLRDV-AL infection cycle, and virulence propensity. This will provide a basis for developing molecular biocontrol of potential new variants of CLRDV that may pose a greater threat in cotton.

Chapter 2 of this thesis was published in Frontiers in Agronomy (Akinyuwa et al., 2023; | https://doi.org/10.3389/fagro.2023.1235168). Chapter 3 was submitted to Virus Research (Akinyuwa and Kang, 2023) and is currently under review.