Other Cocadviroids

Viroids represent a threat to the citrus industry and also display an intricate matter for citrus tristeza virus (CTV) control as most of the commercial citrus rootstocks that are resistant/tolerant to CTV appear to be highly susceptible to viroid infection. Therefore, a detailed knowledge of the viroid’s incidence and distribution, along with the assessment of unexplored epidemiological factors leading to their occurrence, are necessary to further improve control measures. Herein, a large-scale epidemiological study of citrus viroids in five districts, 38 locations and 145 fields in Greece is presented, based on the analysis of 3005 samples collected from 29 cultivars of six citrus species. We monitored the occurrence of citrus exocortis (CEVd), hop stunt (HSVd), citrus dwarfing (CDVd), citrus bark cracking (CBCVd), and citrus bent leaf (CBLVd) viroids, and addressed their epidemiological patterns and factors shaping their population structure. Our results show a high frequency and wide distribution of four viroids in all areas and in almost all hosts, whereas CBLVd occurrence was restricted to Crete. Mixed infections were found in all districts in which a wide spread of viroids was observed. We identified a potential pathogens’ different preferences that could be partially explained by the host and cultivar, including the type of infection (single or mixed) and the number of viroids in the mixed infections. Overall, this work provides the first detailed epidemiological study on citrus viroids, enriching our knowledge for the implementation, production, and distribution of certified citrus propagative material, and the development of sustainable control strategies.

Section: Discussionsupporting

confidence: 78%

Incidence and Epidemiology of Citrus Viroids in Greece: Role of Host and Cultivar in Epidemiological Characteristics

Mathioudakis

Tektonidis

Karagianni

et al. 2023

“…HLVd can be transmitted over long distances and can be introduced into hop gardens by infected propagative materials. HLVd transmits within the hop yards mechanically, by grafting and vegetative propagation, and by contaminated tools or machinery [ 15 ]. HLVd transmission by either pollen or seed has been reported as being either low or non-existing, respectively [ 10 , 16 ].…”

Section: Host Range and Transmission Of Hlvdmentioning

confidence: 99%

“…Although HLVd-infected hop plants are symptomless, infection significantly reduces both cone yield and either the bitter acid or the essential oil content in the hop cones of sensitive cultivars [ 8 ]. Currently, HLVd has been reported in commercial hop yards in Australia, New Zealand, China, Japan, Republic of Korea, Russia, Slovenia, Poland, Germany, the Czech Republic, Hungary, France, Spain, Portugal, the United Kingdom, South Africa, the USA and Brazil [ 15 ]. However, due to the asymptomatic nature of the HLVd infection in most of these hop cultivars, these HLVd infections have long gone unnoticed.…”

Section: Hlvd-associated Symptoms In Hopsmentioning

confidence: 99%

“…These measures have seen the virtual elimination of HSVd from the Kirin Brewery yards in Japan [ 10 ]. Among the different heat and chemical treatments tested for tool sanitation against viroids, the most reliable and widely used one is an aqueous solution of at least 5% household bleach (sodium hypochlorite, minimum 1% available chlorine) [ 15 ]. However, the treatment of greenhouse tools with 10% regular Clorox bleach (an active ingredient of 5.25% sodium hypochlorite [NaOCl]) for 10 s was found to be effective against the transmission of PSTVd in tomatoes [ 38 ].…”

Section: Detection and Management Of Hlvd Infectionmentioning

confidence: 99%

See 1 more Smart Citation

Hop Latent Viroid: A Hidden Threat to the Cannabis Industry

Adkar-Purushothama

Shimmen

Perreault

2023

Hop latent viroid (HLVd) is the biggest concern for cannabis and hop growers worldwide. Although most HLVd-infected plants remain asymptomatic, research on hops has demonstrated a decrease in both the α-bitter acid and terpene content of hop cones, which affects their economic value. The HLVd-associated “dudding” or “duds” disease of cannabis was first reported in 2019 in California. Since then, the disease has become widespread in cannabis-growing facilities across North America. Although severe yield loss associated with duds disease has been recorded, little scientific information is available to growers in order to contain HLVd. Consequently, this review aims to summarise all of the scientific information available on HLVd so as to be able to understand the effect of HLVd on yield loss, cannabinoid content, terpene profile, disease management and inform crop protection strategies.

“…Infection of coconut palm trees by CCCVd is detrimental as it killed over 40 million coconut palm trees in the Philippines at a cost of four billion US dollars [ 6 ]. Citrus bark cracking viroid (CBCVd) infects citrus species with no measurable impact [ 14 ], however, when it infects hops it causes an aggressive disease that kills plants in 3–5 years [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Next-Generation Sequencing and CRISPR/Cas13 Editing in Viroid Research and Molecular Diagnostics

Hadidi

2019

Viroid discovery as well as the economic significance of viroids and biological properties are presented. Next-generation sequencing (NGS) technologies combined with informatics have been applied to viroid research and diagnostics for almost a decade. NGS provides highly efficient, rapid, low-cost high-throughput sequencing of viroid genomes and of the 21–24 nt vd-sRNAs generated by the RNA silencing defense of the host. NGS has been utilized in various viroid studies which are presented. The discovery during the last few years that prokaryotes have heritable adaptive immunity mediated through clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated Cas proteins, have led to transformative advances in molecular biology, notably genome engineering and most recently molecular diagnostics. The potential application of the CRISPR-Cas13a system for engineering viroid interference in plants is suggested by targeting specific motifs of three economically important viroids. The CRISPR-Cas13 system has been utilized recently for the accurate detection of human RNA viruses by visual read out in 90 min or less and by paper-based assay. Multitarget RNA tests by this technology have a good potential for application as a rapid and accurate diagnostic assay for known viroids. The CRISPR/Cas system will work only for known viroids in contrast to NGS, but it should be much faster.