This datasheet on Potato leafroll virus covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Vectors & Intermediate Hosts, Diagnosis, Biology & Ecology, Seedborne Aspects, Impacts, Prevention/Control, Further Information.

Potato leafroll virus

Since the first report of existence of phytoplasma disease in 1874 in India, now more than 172 plant species are reported to be the host of ten different groups of phytoplasmas. The phytoplasma diseases are well documented from all parts of the country and aster yellows group (16SrI) is the most prevalent and widespread group followed by 16SrII, 16SrVI, 16SrXI and 16SrXIV groups. Sesame phyllody, brinjal little leaf, sugarcane grassy shoot, sandal spike, coconut root wilt, areca nut yellow leaf and many ornamentals and vegetables maladies are the major phytoplasma threats in India causing serious economic losses every year. Nearly a dozen of leafhopper and planthopper species have been identified as natural vectors and more than 40 weed species have been identified as natural reservoirs of different phytoplasma strains. A large number of new phytoplasma strains on several crops have been characterized in India during last decade, which revealed that phytoplasmas are more diverse than the earlier thought. Very recently two draft genome sequences of 16SrXI (sugarcane grassy shoot) and 16SrXIV (Bermudagrass white leaf disease) have been submitted from India which open-ups the possibilities of studies on functional genomics. Mixed infections of phytoplasmas and viruses have also emerged as serious problems in several crops and are responsible for more synergistic losses. Nested PCR assays have been routinely employed to detect phytoplasma strains in symptomatic plants and insect vectors by utilizing 16S rRNA, 16Sr-23S rRNA spacer region and several multilocus gene specific primers. However, new developed isothermal amplifications methods (LAMP and RPAs) for sensitive and quick detection of phytoplasmas need to be explored for easier identification of phytoplasma strains. Multiplex PCR system has also been developed to detect the phytoplasma utilizing nested PCR primers and multilocus gene specific primers in one PCR cycle. Very little attempt has been made to study metabolic interaction in phytoplasma hosts and insects in India. However, some efforts in last decade has been made to elucidate the host responses at biochemical, genomics, proteomics and metabolomic levels for understanding the host–pathogen interactions but still more concentrated efforts need to be explored that will help to formulate strategies for controlling phytoplasma diseases. Presently the suggested effective management practices in India are: pruning infected portions, growing resistant varieties, heat therapy, use of tertracycline, control of insect vectors and natural host reservoirs. However, none of them have completely proved successful. Future approach on epidemiology, resistance, host-pathogen-insect interaction, full genome sequencing of major phytoplasma strains and RNA interference needs to be focussed in India for a better understanding and management of these peculiar microbial pathogens.

Our understanding about phytoplasma research scenario in India

The family Luteoviridae comprises of three genera Luteovirus, Enamovirus and Polerovirus, of which, only two genera Luteovirus and Polerovirus are known in India. Though luteovirus and polerovirus infects many crops throughout the world, only a few have been documented in India. Luteoviruses were reported in field crops like barley (barley yellow dwarf virus) and chickpea (chickpea stunt virus), while polerovirus was recorded from potato, jute (potato leaf roll virus [PLRV]) sugarcane (sugarcane yellow leaf virus [SCYLV]) and cotton (cotton leaf roll dwarf virus) crops from India. SCYLV and PLRV are the most important poleroviruses as they are of serious constraints in all the sugarcane and potato growing states of India. SCYLV infection causes 39–43% reductions in plant growth and 30–34% loss in yield in sugarcane. The virus is mainly transmitted through infected seed canes. The secondary spread of the virus in the field is by the aphid vectors. PLRV is reported to cause 50–60% yield losses in potato crop and this virus is tuber borne and transmitted mainly by aphid vectors in a circulative non-propagative manner. The complete genome sequences SCYLV and PLRV isolates from sugarcane and potato are available from India. This book chapter deals with an uptodate information available on distribution, biological properties, identification, serological relationships, genetic diversity and transmission of the luteoviruses and poleroviruses reported on different crops from India.

The Current Status of Luteovirus and Polerovirus Research in India

Following a request from the EU Commission, the Panel on Plant Health has addressed the pest categorisation of non-EU isolates of potato leafroll virus (PLRV). The information currently available on geographical distribution, biology, epidemiology, potential entry pathways, potential additional impact and availability of control measures of non-EU isolates of PLRV has been evaluated with regard to the criteria to qualify as a potential Union quarantine pest. Because non-EU isolates of PLRV are absent from the EU, they do not meet one of the requirements to be regulated as a regulated non-quarantine pest (RNQP) (presence in the EU); as a consequence, the Panel decided not to evaluate the other RNQP criteria for these isolates. This categorisation was performed considering two groups of PLRV isolates: those associated with the tomato yellow top disease (PLRV-TYTV), not reported from the EU, and all other isolates (hereafter referred to as PLRV), with a worldwide distribution. Isolates of PLRV-TYTV could potentially have an additional impact over the current situation in the EU and therefore meet all the criteria to qualify as a potential Union quarantine pest. All other non-EU PLRV isolates, should they be introduced, are not expected to have additional impact and therefore do not meet this criterion to qualify as a potential Union quarantine pest.

https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2020.5939

Pest categorisation of potato leafroll virus (non‐EU isolates)

CMV infected in Corchorus olitorius plants cultivated on a farm in Miyagi Prefecture, Japan, was analyzed via western blotting using antibody against the coat protein of cucumber mosaic virus (CMV). The virus was purified from Nicotiana benthamiana leaves rub-inoculated with a homogenate of infected C. olitorius containing CMV genomic RNA. The CMV isolate was named CMV-Co-46. Nucleotide sequence analysis of RNA1, 2, and 3 cDNA grouped CMV-Co-46 in subgroup IA. Inoculation of C. olitorius cotyledons with CMV-Co-46 resulted in slight yellowing on primary and secondary leaves seven days after inoculation and severely suppressing plant growth. However, no further systemic spread was observed and the infected plants were able to recover from the stunting symptoms. These findings suggest that restricted infection followed by recovery from systemic stunting may be a unique feature of the C. olitorius response to CMV. Management of CMV infection at an early growth stage is therefore important in obtaining healthy nursery plants of C. olitorius.

First identification and characterization of cucumber mosaic virus from Corchorus olitorius in Japan

Jute (Corchorus olitorius L.) is an important bast fiber crop that is mainly grown in the Southeast Asian countries like India, Bangladesh, Nepal, China, Indonesia, Thailand, Myanmar, and a few South American countries. In June 2013, symptoms suggestive of a viral disease were noticed on jute (cv. JRO524) in an experimental field of the CRIJAF research farm, Barrackpore, India, and the incidence of the disease was less than 2%. The infected plants showed stunted growth and short height. Mostly the upper leaves elongated with curling and coiling of lamina. Puckering and shoe string effect were also noticed. Petioles and stipules of the affected leaves were exceptionally longer. Although initially the incidence was low, it may spread to larger areas in subsequent years. Because the jute fiber is extracted from the stem, stunted growth and short height would badly affect the fiber yield and quality. Ten symptomatic and ten asymptomatic healthy looking samples were collected from the field. Corchorus golden m...

https://krishi.icar.gov.in/jspui/bitstream/123456789/61911/1/Plant%20Disease%20%20PLRV.pdf

First Report of Potato leaf roll virus (PLRV) Naturally Occurring on Jute (Corchorus olitorius) in India.

Flax or linseed is grown as a fiber or oilseed crop in tropical and temperate regions. It is commercially cultivated in many countries of the world including Canada, China, India, the United States, Ethiopia, Pakistan, Russia, Poland, and Argentina (1). In December 2013, symptoms suggestive of phytoplasma infection were noticed on flax in different experimental fields of Central Research Institute for Jute and Allied Fibres (CRIJAF) research farm, Barrackpore, India, and the incidence was less than 2%. Because incidence of phytoplasma diseases are increasing worldwide, occurrence of a phytoplasma in a new geographical area poses an imminent threat. The infected plants showed floral virescence, phyllody, and stem fasciation (flattened stem). Floral malformation was very conspicuous with abnormal structures replacing normal flowers. All the floral parts, including petals, turned into green leaves. Total DNA was extracted from leaf mid veins of three symptomatic and three asymptomatic plants using a DNeasy P...

P. G. Karmakar

Papers

First Report of Potato leaf roll virus (PLRV) Naturally Occurring on Jute (Corchorus olitorius) in India.

First Report of a 16Sr I-B Phytoplasma Associated with Phyllody and Stem Fasciation of Flax (Linum usitatissimum) in India