Loquat (Eriobotrya japonica) Is a New Natural Host of Apple Stem Pitting Virus

Abstract

Loquat (Eriobotrya japonica) is a minor but important woody crop cultivated in Asia and Europe. High-throughput sequencing (HTS) analysis of an asymptomatic loquat plant using RNAseq Illumina technology has allowed the detection for the first time of apple stem pitting virus (ASPV), the type species of the genus Foveavirus in the family Betaflexiviridae, infecting this crop. A nearly complete genome of 9303 nts (ASPV-SL61) reconstructed bioinformatically shows the typical genomic structure of this viral species and a highest nucleotide identity (85.9%) with the Chinese ASPV isolate YLX from pear. A close phylogenetic relationship between ASPV-SL61 and ASPV-YLX has been confirmed by the sequence analysis of full-length ASPV genomic sequences available in the databases. In fact, a phylogenetic study based on a partial CP N-terminal sequence previously proposed to be involved in host adaptation has shown that ASPV-SL61 loquat isolate is more closely related to ASPV pear isolates. The presence of ASPV in loquat has been further confirmed by RT-PCR and Sanger sequencing and DAS-ELISA. An incidence of 15% was determined in one of the loquat Spanish growing areas. The sequence analysis of the partial CP sequences amplified by RT-PCR has shown a high level of variability between loquat isolates. To our knowledge, this is the first record of loquat as a natural host of ASPV.

Molecular Characterization of the Coat Protein Gene of Greek Apple Stem Pitting Virus Isolates: Evolution through Deletions, Insertions, and Recombination Events

“…Moreover, the green crinkle disease in apples and a severe quince disease have been attributed to a distinct variant of ASPV, known as apple green crinkle-associated virus (AGCaV) [ 9 , 10 ]. Recent reports have expanded the known natural host range of ASPV, with its detection in ornamental and wild Rosaceae species and an exceptional report in cherries [ 2 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], further suggesting the potential existence of (a) yet unidentified transmission mode(s). In Greece, ASPV was first identified by molecular assays in apple, pear and quince [ 5 , 6 ], and later on, noncultivated species (ornamental and wild quince and pear) were also reported as natural hosts of ASPV [ 14 ].…”

First Detection and Molecular Characterization of Apple Stem Grooving Virus, Apple Chlorotic Leaf Spot Virus, and Apple Hammerhead Viroid in Loquat in Spain

“…In summer 2020, a random survey was carried out in one of the main Spanish loquatgrowing areas, Callosa d'en Sarrià, Alicante. A total of 91 samples from different loquat cultivars were randomly collected and tested by specific RT-PCR detection methods for ASGV, ACLSV, LoVA, and ASPV [3,6,[27][28][29]. Only five of the samples collected showed virus-like symptoms, in particular leaf chlorotic mottling, while the remaining plants sampled were symptomless.…”

“…It produces early spring sweet fruits that are highly appreciated for its organoleptic and medicinal properties [2]. Loquat is cultivated in around 30 countries in Asia and Europe, with Spain being the main European producer and exporter with an annual production of 40,000 tones [2,3]. Despite being a minor crop, loquat is very valuable in the Mediterranean region of Spain, where it represents an important economic income and contributes to increasing the genetic diversity of crop production [3,4].…”

“…Among them, plant viruses are related to 50% of emerging diseases and produce important economic losses [5]. Loquat has been reported to be infected by four viruses: apple stem grooving virus (ASGV), apple chlorotic leaf spot virus (ACLSV), loquat virus A (LoVA), and apple stem pitting virus (ASPV) [2,3,6].…”

Biological and molecular characterization of two isolates of apple stem grooving virus revealed distinct properties and indicates virus emergence driven by recombination

“…ASGV is mostly found in mixed infection with other apple viruses like apple stem pitting virus and apple chlorotic leaf spot virus in apple, pear, loquat, etc. (Kumar et al, 2012;Liu et al, 2019;Morán et al, 2020;Nickel & Fajardo, 2014). The ASGV infection was reported from Lilium (lily), citrus, Pyrus communis (pear), Malus domestica (apple) but recently, the virus is known with expanding host range like Eriobotrya japonica (loquat), Ficus palmata (fig), Polygonatum kingianum (Solomon's seal), Prunus cerasoides (wild cherry), Bambusa vulgaris (bamboo), Rosa multiflora (multiflora rose), Bauhinia variegata (orchid tree), Paeonia lactiflora (peony), and many other hosts (Bhardwaj & Hallan, 2019b;Bhardwaj et al, 2015Bhardwaj et al, , 2017Chen et al, 2019;Clover et al, 2003).…”