Incidence of Garlic common latent virus in Argentina, and phylogenetic and recombination analyses of isolates

Abstract

-The objective of this work was to estimate the incidence and prevalence of Garlic common latent virus (GarCLV) in the main production regions of garlic (Allium sativum) in Argentina, and to perform phylogenetic and recombination analyses in isolates from these regions. Leaf samples (3,050) were taken from four garlic commercial types, in 13 departments of the four main garlic-producing provinces of Argentina, in a 1,175-ha sampling area. Virus infection was evaluated with DAS-Elisa test using specific antiserum, and the phylogenetic and recombination analyses were done with capsid protein (CP) nucleotide sequence of seven GarCLV isolates from the provinces. The incidence of GarCLV in the evaluated provinces varied between 6.7 and 22% of the samples, whereas the prevalence varied between 52.6 and 70%. In the analysis of garlic commercial types, Morado showed the highest incidence of the virus, in the province of San Juan, whereas Rosado Paraguayo had the lowest incidence, in the province of Cordoba. Nucleotide identity in the CP sequences ranged between 80.3 and 97.6%. The phylogenetic analysis shows the presence of two main groups of GarCLV and of a possible third group that would include only a German isolate. The recombination analysis between isolates from different parts of the world evidences the presence of recombinant isolates from Poland and Australia.

Agronomic performance of both virus-infected and virus-free garlic with different seed bulbs and clove sizes

“…The gain in productivity through the use of virusfree clones has been widely reported in researches (Silva et al, 2010;Melo et al, 2011;Bereda & Paduch-Cichal, 2016) and marketable plantations. According to Resende et al (2000), the virus-free clone shows a vegetative vigor superior to virus-infected ones, which leads to an increased productivity.…”

“…Productivity reduction varies according to the levels of viral infection of the cultivar, genetic material, and years of conventional clove multiplication. In this sense, Silva et al (2010) observed a higher productivity in cloves from tissue culture for nine consecutive years, in comparison to the conventional multiplication. Depending on the cultivar used, the production tends to reduce from the third or fourth year of successive cultivation.…”

“…Virus multiplication and dissemination in garlic, from one production cycle to another, is facilitated by propagules (bulbs and cloves) due to the vegetative propagation. The presence of a viral complex in garlic, formed by the genera Allexivirus, Carlavirus, and Potyvirus (Mituti et al, 2011(Mituti et al, , 2015Oliveira et al, 2014;Torrico et al, 2015) causes a drastic reduction of the vegetative vigor and productivity of the crop over time (Perotto et al, 2010;Oliveira et al, 2014;Velásquez-Valle et al, 2017), leading to the degeneracy of cultivars.…”

“…The virus-free garlic technique has been consolidating as an essential technology for increasing the competitiveness of garlic production chain in Brazil. Significant increases of productivity and quality of bulbs provided by the use of virus-free garlic seed have been observed in both comparative tests with infected materials and their adoption in marketable plantations (Silva et al, 2010;Melo et al, 2011;Bereda & Paduch-Cichal, 2016).…”

Phylogenetic and diversity analyses of Garlic common latent virus based on the TGB and CP gene sequence

“…ORF5 contains a coat protein (CP) encoding sequence (Yadav & Majumder 2019). Earlier phylogenetic analyses on the complete nucleotide (nt) sequence of the CP region showed that most GarCLV isolates were divided into two major groups only, which had relatively low diversities between them (Parrano et al 2012;Pramesh & Baranwal 2013;Torrico et al 2015). However, the presence of a third phylogroup that was predicted by Parrano et al (2012) has been proven recently by Santosa and Ertunc (2020).…”