Identification and Characterization of Four New Plant Pararetroviruses (Genus: Badnavirus) Infecting Ornamental Crops

Abstract

Floriculture crops include flowering and foliage plants, cut flowers/foliage, patio, herbaceous perennials, and potted ornamentals, vegetables, and herbs. In the United States of America (USA) this industry was valuated at US$4.80 billion for 2020, and despite the COVID-19 pandemic went up 9% with respect to the previous year (USDA, NASS 2021). Plant viruses affecting ornamental crops can be detrimental, reducing the plant vigor and visual appearance. Some viral diseases are transmitted during vegetative propagation while others are transmitted by vectors. Disease detection is vital for the management of viral diseases and without accurate detection the disease control is limited. The detection of infectious (episomal) forms of plant pararetroviruses in the genus Badnavirus is difficult due to the common presence of endogenous virus sequences integrated into the plant genome and their potential for disease activation. The objectives of this research were the identification and characterization of four new badnaviruses infecting ornamental crops Ming aralia (Polyscias fruticosa), Aglaonema ‘Chinese evergreen’ (Aglaonema modestum), cycads (Zamia fischeri), and Spiraea x bumalda ‘Anthony Waterer’. This work resulted in the complete genome sequencing of polyscias mosaic virus (PoMV), aglaonema bacilliform virus (ABV), cycad leaf necrosis virus (CLNV), and spiraea yellow leafspot virus (SYLSV). These sequences were deposited in the NCBI under the accession’s numbers MW080369 and MW080370 for SYLSV-MN and SYLSV-MD, respectively. CLNV was assigned to the accession number EU853709, ABV to MH384837, and PoMV MH475918. Additionally, detection primers were designed and protocols for detection of SYLSV and CLNV. These results are useful for plant pathologists and plant breeders, and the green industry growing and trading these crops.