Prospective alternate hosts of an emerging polerovirus in cotton landscapes in the southeastern United States

Authors: PANDEY, SUDEEP - University Of Georgia; BAG, SUDEEP - University Of Georgia; ROBERTS, PHILIP - University Of Georgia; CONNER, KASSIE - Auburn University; Balkcom, Kipling; Price, Andrew; JACOBSON, ALANA - Auburn University; SRINIVASAN, RAJAGOPALBABU - University Of Georgia

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2022
Publication Date: 10/13/2022
Citation: Pandey, S., Bag, S., Roberts, P., Conner, K., Balkcom, K.S., Price, A.J., Jacobson, A.L., Srinivasan, R. 2022. Prospective alternate hosts of an emerging polerovirus in cotton landscapes in the southeastern United States. Viruses. 14(10):2249. https://doi.org/10.3390/v14102249.
DOI: https://doi.org/10.3390/v14102249

Interpretive Summary: The identification of alternate hosts that can act as virus inoculum sources and vector reservoirs in the landscape is critical to understanding virus epidemics. Cotton leafroll dwarf virus (CLRDV) is a serious pathogen in cotton production and is transmitted by the cotton/melon aphid. CLRDV was first reported in the United States in Alabama in 2017 and has since established itself in the southeastern United States. The role of alternate hosts in CLRDV establishment is not clear. As a result, researchers at the Univ. of Georgia, Auburn Univ, and USDA-ARS in Auburn, AL examined fourteen common plant species in the landscape including crops, weeds, and ornamentals (hollyhock, marshmallow, country mallow, abutilon, arrowleaf sida, okra, hibiscus, squash, chickpea, evening primrose, henbit, palmer amaranth, and teaweed) that also included an experimental host to determine their potential as alternate hosts of CLRDV via aphid-mediated transmission assays. CLRDV was detected following inoculation in hibiscus, okra, N. benthamiana, palmer amaranth, and teaweed but not in the others. CLRDV accumulation was highest in the experimental host compared with cotton and other hosts. However, aphids feeding on CLRDV-infected teaweed, hibiscus, and okra alone were able to acquire CLRDV and back-transmit it to non-infected cotton seedlings. Overall, this study demonstrated that plant hosts in the agricultural landscape can serve as CLRDV inoculum sources and as aphid reservoirs and could possibly play a role in the reoccurring epidemics of CLRDV in the southeastern United States. Correctly identifying potential hosts or aphid reservoirs for CLRDV will be critical to the development of future CLRDV control strategies.

Technical Abstract: The identification of alternate hosts that can act as virus inoculum sources and vector reservoirs in the landscape is critical to understanding virus epidemics. Cotton leafroll dwarf virus (CLRDV) is a serious pathogen in cotton production and is transmitted by the cotton/melon aphid, Aphis gossypii, in a persistent, circulative, and non-propagative manner. CLRDV was first reported in the United States in Alabama in 2017 and thereafter from several cotton-producing states. CLRDV has since established itself in the southeastern United States. The role of alternate hosts in CLRDV establishment is not clear. Fourteen common plant species in the landscape in-cluding crops, weeds, and ornamentals (hollyhock, marshmallow, country mallow, abutilon, arrowleaf sida, okra, hibiscus, squash, chickpea, evening primrose, henbit, palmer amaranth, and teaweed) and an experimental host (Nicotiana benthamiana Domin) were tested as potential alternate hosts of CLRDV via aphid-mediated transmission assays. CLRDV was detected following inoculation in hibiscus, okra, N. benthamiana, palmer amaranth, and teaweed by RT-PCR but not in the others. CLRDV accumulation determined by RT-qPCR was the highest in N. benthamiana compared with cotton and other hosts. However, aphids feeding on CLRDV-infected teaweed, hibiscus, and okra alone were able to acquire CLRDV and back-transmit it to non-infected cotton seedlings. Additionally, some of the alternate CLRDV hosts supported aphid development on par with cotton. But in a few instances, aphid fitness was reduced when compared with cotton. Overall, this study demonstrated that plant hosts in the agricultural landscape can serve as CLRDV inoculum sources and as aphid reservoirs and could possibly play a role in the reoccurring epidemics of CLRDV in the southeastern United States.