Immunodiagnosis of episomal Banana streak MY virus using polyclonal antibodies to an expressed putative coat protein

Emerging and Re-Emerging Diseases Caused by Badnaviruses

New and emerging plant diseases are caused by different pathogens including viruses that often cause significant crop losses. Badnaviruses are pararetroviruses that contain a single molecule of ds DNA genome of 7 to 9 kb in size and infect a large number of economically important crops such as banana and plantains, black pepper, cacao, citrus, grapevine, pineapple, sugarcane, sweet potato, taro, and yam, causing significant yield losses. Many of the species in the genus have a restricted host range and several of them are known to infect a single crop. Combined infections of different virus species and strains offer conditions that favor the development of new strains via recombination, especially in vegetatively propagated crops. The primary spread of badnaviruses is through vegetative propagating materials while for the secondary spread, they depend on insects such as mealybugs and aphids. Disease emerges as a consequence of the interactions between host and pathogens under favorable environmental conditions. The viral genome of the pararetroviruses is known to be integrated into the chromosome of the host and a few plants with integrants when subjected to different kinds of abiotic stress will give rise to episomal forms of the virus and cause disease. Attempts have been made to develop management strategies for badnaviruses both conventionally and using precision breeding techniques such as genome editing. Until 2016 only 32 badnavirus species infecting different crops were known, but in a span of six years, this number has gone up to 68. The current review highlights the emerging disease problems and management options for badnaviruses infecting economically important crops.

Viruses Infecting Trees and Herbs That Produce Edible Fleshy Fruits with a Prominent Value in the Global Market: An Evolutionary Perspective

Trees and herbs that produce fruits represent the most valuable agricultural food commodities in the world. However, the yield of these crops is not fully achieved due to biotic factors such as bacteria, fungi, and viruses. Viruses are capable of causing alterations in plant growth and development, thereby impacting the yield of their hosts significantly. In this work, we first compiled the world's most comprehensive list of known edible fruits that fits our definition. Then, plant viruses infecting those trees and herbs that produce fruits with commercial importance in the global market were identified. The identified plant viruses belong to 30 families, most of them containing single-stranded RNA genomes. Importantly, we show the overall picture of the host range for some virus families following an evolutionary approach. Further, the current knowledge about plant-virus interactions, focusing on the main disorders they cause, as well as yield losses, is summarized. Additionally, since accurate diagnosis methods are of pivotal importance for viral diseases control, the current and emerging technologies for the detection of these plant pathogens are described. Finally, the most promising strategies employed to control viral diseases in the field are presented, focusing on solutions that are long-lasting.

Efficient immunodiagnosis of Citrus yellow mosaic virus using polyclonal antibodies with an expressed recombinant virion-associated protein

Citrus yellow mosaic virus (CYMV) is a member of genus Badnavirus of the family Caulimoviridae. It is the causal agent of citrus yellow mosaic disease in citrus and causes reduction in yield. As the virus is vegetative propagated by grafting, development of high-throughput diagnosis methods based on serological techniques is a prerequisite for production of healthy virus-free planting material. The current study describes the development of polyclonal antibodies raised in rabbits against purified recombinant virion-associated protein (rVAP) encoded by ORF-II of CYMV. The specificity of developed antiserum was evaluated in immunosorbent electron microscopy (ISEM), antigen-coated plate-enzyme linked immunosorbent assay (ACP-ELISA) and immunocapture PCR (IC-PCR). The antiserum specifically reacted up to a dilution of 1:2000 in ACP-ELISA for detection of CYMV-infected plants. The antiserum was validated by screening CYMV-infected plants maintained in the glass house through ACP-ELISA. To the best for our knowledge, this is the first report on production of polyclonal antiserum using recombinant virion-associated protein as fusion protein, which could be used for screening CYMV-infected plants by ELISA and IC-PCR. These immunodiagnostic methods can be effectively employed in routine indexing of citrus and in quarantine process.

Subpopulation level variation of banana streak viruses in India and common evolution of banana and sugarcane badnaviruses

Genome sequences of three episomal Banana streak MY virus (BSMYV) isolates sampled from triploid banana hybrids (Chini Champa: AAB; Malbhog: AAB and Monthan: ABB), grown in North-East and South India are reported in this study by sequence-independent improved rolling circle amplification (RCA). RCA coupled with restriction fragment length polymorphism revealed diverse restriction profiles of five BSMYV isolates. Nucleotide substitution rates of BSMYV subpopulation and Banana streak OL virus subpopulation was 7.13 × 10(-3) to 1.59 × 10(-2) and 2.65 × 10(-3) to 5.49 × 10(-3), respectively, for the different coding regions. Analysis of the genetic diversity of banana and sugarcane badnaviruses revealed a total of 32 unique recombination events among banana and sugarcane badnaviruses (inter BSV-SCBV), in addition to the extensive recombination with in banana streak viruses and sugarcane bacilliform viruses (intra-BSV and intra-SCBV). Many unique fragments were shown to contain similar ruminant sequence fragments which indicated the possibility that the two groups of badnaviruses or their ancestors to colonise same host before making the host shift. The distribution of recombination events, hot-spots (intergenic region and C-terminal of ORF3) as well as cold-spots (distributed in ORF3) displayed the mirroring of recombination traces in both group of badnaviruses. These results support the hypothesis of relatedness of banana and sugarcane badnaviruses and the host and geographical shifts that followed the fixation of the species complex appear to be a recent event.