Weed-infecting viruses in a tropical agroecosystem present different threats to crops and evolutionary histories.

Minor R. Maliano,Maria R. Rojas,Robert L. Gilbertson,Mônica A. Macedo,Hanu R. Pappu

doi:10.1371/journal.pone.0250066

Minor R. Maliano, Maria R. Rojas + Show 3 more

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https://doi.org/10.1371/journal.pone.0250066

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Abstract

In the Caribbean Basin, malvaceous weeds commonly show striking golden/yellow mosaic symptoms. Leaf samples from Malachra sp. and Abutilon sp. plants with these symptoms were collected in Hispaniola from 2014 to 2020. PCR tests with degenerate primers revealed that all samples were infected with a bipartite begomovirus, and sequence analyses showed that Malachra sp. plants were infected with tobacco leaf curl Cuba virus (TbLCuCV), whereas the Abutilon sp. plants were infected with a new bipartite begomovirus, tentatively named Abutilon golden yellow mosaic virus (AbGYMV). Phylogenetic analyses showed that TbLCuCV and AbGYMV are distinct but closely related species, which are most closely related to bipartite begomoviruses infecting weeds in the Caribbean Basin. Infectious cloned DNA-A and DNA-B components were used to fulfilled Koch’s postulates for these diseases of Malachra sp. and Abutilon sp. In host range studies, TbLCuCV also induced severe symptoms in Nicotiana benthamiana, tobacco and common bean plants; whereas AbGYMV induced few or no symptoms in plants of these species. Pseudorecombinants generated with the infectious clones of these viruses were highly infectious and induced severe symptoms in N. benthamiana and Malachra sp., and both viruses coinfected Malachra sp., and possibly facilitating virus evolution via recombination and pseudorecombination. Together, our results suggest that TbLCuCV primarily infects Malachra sp. in the Caribbean Basin, and occasionally spills over to infect and cause disease in crops; whereas AbGYMV is well-adapted to an Abutilon sp. in the Dominican Republic and has not been reported infecting crops.

Highlights

The genus Begomovirus is comprised of a large and diverse group of plant viruses that possess a circular, single-stranded DNA genome encapsidated into twin quasi-icosahedral virions (18 x 30 nm) [1,2,3]
These results suggest that the Malachra sp. plants with golden/yellow mosaic symptoms were associated with variants of tobacco leaf curl Cuba virus (TbLCuCV), whereas the Abutilon sp. plants with these symptoms were associated with variants of a putative new begomovirus species
Malachra sp. is an invasive weed found in association with irrigation ditches and disturbed areas around agricultural fields in Hispaniola and other countries of the Caribbean Basin, whereas Abutilon sp. occurs in this environment, but was less common based in our surveys

Summary

Introduction

The genus Begomovirus (family Geminiviridae) is comprised of a large and diverse group of plant viruses that possess a circular, single-stranded (ss) DNA genome encapsidated into twin quasi-icosahedral virions (18 x 30 nm) [1,2,3]. These viruses infect dicotyledonous plants and cause numerous economically important diseases of fiber, fruit, ornamental and vegetable crops, mostly in tropical and subtropical regions of the world [4]. An ~200 nucleotide (nt) noncoding sequence is shared between cognate DNA-A and DNA-B components, and this common region (CR) maintains the specificity of replication for these components. The sequences of the DNA-A and DNA-B components are different, and both components are needed for induction of typical disease symptoms [1,2,8]

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