Characterization and Detection of Passiflora Mottle Virus and Two Other Potyviruses Causing Passionfruit Woodiness Disease in Vietnam

Abstract

Passionfruit plantation in Vietnam increased to 10,000 ha in 2019. However, the outbreaks of passionfruit woodiness disease (PWD) have become a serious threat for the production. In this study, five virus isolates DN1, DN4, NA1, GL1 and GL2 were collected from different areas of Vietnam. Their causal roles for PWD were verified by back inoculation to passionfruit. Analyses of coat protein (CP) and genomic sequences revealed that GL1 isolate is closely related to East Asia Passiflora virus (EAPV) AO strain of Japan (polyprotein nt/aa identities of 98.1% / 98.2%), while GL2 isolate is related to Telosma mosaic virus (TelMV) isolate PasFru, China (polyprotein nt/aa identities of 87.1% / 90.9%). CP comparison, host range and cytological characterization indicated that DN1, DN4 and NA1 are potyviruses, but different from EAPV and TelMV. Phylogenic analyses of their CP and genome sequences indicated that these three isolates and passionfruit severe mottle-associated virus Fujian isolate of China belong to a distinct clade, which does not satisfy the threshold (76% nt identity of polyprotein) to be regarded as any of potyviral species. Thus, a new species name of “Passiflora mottle virus” has been proposed by ICTV. A rabbit antiserum was produced against the CP of DN1 and it can discriminate Passiflora mottle virus (PaMoV) from TelMV and EAPV in western blotting and ELISA without cross reactions. Field surveys of 240 samples by ELISA and RT-PCR disclosed that PWD in Vietnam is mainly caused by PaMoV; followed by EAPV, mixed-infection of PaMoV/EAPV, and rare cases of TelMV.

A clade of telosma mosaic virus from Thailand is undergoing geographical expansion and genetic differentiation in passionfruit of Vietnam and China

“…In the past decade, Taiwan has served as a center for the dispersal of passionfruit propagation materials. Therefore, it is anticipated that EAPV, or some other virus species that had been prevalent in Taiwan, will be the dominating potyvirus in the passionfruit (Do et al 2021). The results of this study do not provide direct evidence to deny this assumption.…”

“…Shortly thereafter, TelMV was detected in passionfruit in several different provinces of China's mainland, as well as in Taiwan region (Xie et al 2017;Chen et al 2018). More recently, TelMV was detected from passionfruit in Vietnam (Ha et al 2008;Do et al 2021). The first known plant host of TelMV is not passionfruit.…”

Telosma mosaic virus: An emerging plant RNA virus causing production loss in passion fruit across Asia

“…The TeMV genome is a single-stranded, positive-sense RNA (+ssRNA) that is 9689-10,089 nucleotides in length and enclosed in curved rod-shaped viral particles with a length of 750-770 nm and a diameter of 14 nm (Figure 1a) (Ha, 2007;Ha et al, 2008;Xie, Gao, et al, 2020;Yang et al, 2018). The 5′ end of the TeMV genomic RNA is covalently bonded to viral protein genome-linked (VPg), while the 3′ end has a poly(A) tail (Do et al, 2021;Xie, Gao, et al, 2020). The (Cui & Wang, 2019).…”

“…The TeMV genome is a single‐stranded, positive‐sense RNA (+ssRNA) that is 9689–10,089 nucleotides in length and enclosed in curved rod‐shaped viral particles with a length of 750–770 nm and a diameter of 14 nm (Figure 1a) (Ha, 2007; Ha et al., 2008; Xie, Gao, et al., 2020; Yang et al., 2018). The 5′ end of the TeMV genomic RNA is covalently bonded to viral protein genome‐linked (VPg), while the 3′ end has a poly(A) tail (Do et al., 2021; Xie, Gao, et al., 2020). The viral genome contains a large open reading frame (ORF) translated into a polyprotein that is hydrolysed by viral proteases into the following 10 mature proteins (Figure 1b): first protein (P1), helper component‐protease (HC‐Pro), third protein (P3), first 6‐kDa peptide (6K1), cylindrical inclusion protein (Cl), second 6‐kDa peptide (6K2), nuclear inclusion protein a (NIa) (which is further cleaved into NIa‐VPg protein [NIa‐VPg] and NIa‐protease [NIa‐Pro]), nuclear inclusion protein b (NIb) and coat protein (CP) (Cui & Wang, 2019).…”

“…In 2007, a new virus in the Potyvirus genus named Telosma mosaic virus was described in Vietnam (Ha, 2007;Ha et al, 2008). Telosma mosaic virus (TeMV) was first identified as an infectant of passion fruit in 2014 and has since become one of the most significant pathogens affecting passion fruit production in countries including China, Thailand and Vietnam (Chiemsombat et al, 2014;Do et al, 2021;Xie et al, 2017). TeMV has caused significant losses in yield and quality and is currently regarded as one of the primary risks to passion fruit production.…”