Tobamoviruses of two new species trigger resistance in pepper plants harbouring functional L alleles

Abstract

Tobamoviruses are often referred to as the most notorious viral pathogens of pepper crops. These viruses are not transmitted by invertebrate vectors, but rather by physical contact and seeds. In this study, pepper plants displaying mild mottle and mosaic symptoms were sampled in four different regions of Peru. Upon double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) tests, seven samples cross-reacted weakly with antibodies against pepper mild mottle virus (PMMoV), suggesting the presence of tobamoviruses. When employing RT-PCR, conserved primers amplified cDNA fragments of viruses from two putative new tobamovirus species in the samples. The complete genome of two representative isolates were, therefore, sequenced and analysed in silico. These viruses, which were tentatively named yellow pepper mild mottle virus (YPMMoV) and chilli pepper mild mottle virus (CPMMoV), shared highest nucleotide genome sequence identities of 83 and 85 % with bell pepper mottle virus (BpeMV), respectively. Mechanical inoculation of indicator plants with YPMMoV and CPMMoV isolates did not show any obvious differences in host ranges. These viruses were also inoculated mechanically on pepper plants harbouring different resistance L alleles to determine their pathotypes. Pepper plants carrying unfunctional L alleles (L 0) to tobamoviruses were infected by all isolates and presented differential symptomatology for YPMMoV and CPMMoV. On the other hand, pepper plants carrying L 1, L 2, L 3 and L 4 alleles were resistant to all isolates, indicating that these viruses belong to pathotype P0.

First report of Chili pepper mild mottle virus in calibrachoa in the United States

“…We additionally tested the same four samples with degenerate potyvirus (Gibbs & Mackenzie, New Dis Rep. 2022;46:e12120. wileyonlinelibrary.com/journal/ndr2 1 of 2 https://doi.org/10.1002/ndr2.12120 F I G U R E 2 Chlorosis observed on calibrachoa cuttings infected with Chili pepper mild mottle virus 1997) and orthotospovirus (Chu et al, 2001) primers; no amplicons were observed.CPMMoV was first reported in 2021 from field-grown pepper in Peru(Vélez-Olmedo et al, 2021). To the best of our knowledge, this is the first report of CPMMoV in calibrachoa or any other greenhousegrown ornamental host.…”

“…ON381946‐ON381953) and those from each primer set shared 99–100% nucleotide identity with each other, and 99–100% nucleotide identity with the corresponding regions of CPMMoV isolate Oxampampa4 (MN164455) confirming the presence of this tobamovirus. CPMMoV‐specific CP gene primers (Vélez‐Olmedo et al., 2021) also produced amplicons of the expected size, c. 1,100 bp. No other tobamovirus sequences were detected with any of these primer sets.…”

“…CPMMoV was first reported in 2021 from field‐grown pepper in Peru (Vélez‐Olmedo et al., 2021). To the best of our knowledge, this is the first report of CPMMoV in calibrachoa or any other greenhouse‐grown ornamental host.…”

“…To confirm and extend these serological results, totalRNA was isolated from seven samples using a modified RNeasy protocol (Qiagen, Germany) and tested using a tobamovirus group RT-PCR(Maroon & Zavriev, 2002). The sequence of the RT-PCR amplicons indicated the presence of the recently described tobamovirus, Chili pepper mild mottle virus (CPMMoV;Vélez-Olmedo et al, 2021).…”

Reversion of a resistance‐breaking mutation shows reversion costs and high virus diversity at necrotic local lesions

“…These results show that the virus population at NLL is highly heterogeneous in terms of resistance‐breaking phenotypes. PMMoV isolates of P 1 and P 0 pathotypes have never been reported from nature, which suggest that mutations towards lower, not only higher, pathotype may have important fitness costs, so that PMMoV genotypes of P 1 and P 0 pathotypes would be outcompeted by P 0 and P 1 genotypes of other tobamovirus species commonly found in pepper crops (Fraile et al, 2011 ; Moury & Verdin, 2012 ; Vélez‐Olmedo et al, 2021 ).…”