Rice yellow mottle virus | |
---|---|
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Pisuviricota |
Class: | Pisoniviricetes |
Order: | Sobelivirales |
Family: | Solemoviridae |
Genus: | Sobemovirus |
Species: | Rice yellow mottle virus |
Synonyms | |
rice yellow mottle sobemovirus, pale yellow mottle disease Contents |
Rice yellow mottle virus (RYMV) is a plant pathogenic virus, belonging to the genus Sobemovirus. The genome is a positive-sense single strand RNA of 4450 nucleotides in length and is not polyadenylated. [1] It was first reported in Kenya in 1966 [2] in one of Africa's first cultivation intensification schemes, due to RYMV's association with intensification, [P 1] but DNA analysis of its evolutionary history shows it to have evolved in East Africa in the 19th century. [T 1] [P 2] [P 3] Since its identification in Kenya it has been detected in many countries in sub-Saharan Africa. [3] It has also been detected in Central Africa, but has yet to be seen outside the continent. [4] The genomic organization of RYMV is most similar to that of Cocksfoot mottle sobemovirus. [4] RYMV is one of the better-studied plant-virus pathosystems. [T 2] [5]
RYMV is a single-stranded positive-sense RNA virus. There is a high level of genetic diversity with the RYMV nucleotides, which is roughly 14%. [6] RYMV is a sobemovirus . [7]
RYMV has a massive impact on rice crops. Streaking, mottling, discoloration and malformation of leaves as well as death of infected young plants are all typical signs of RYMV infection. [2] [8] Crop losses can be 25–100%. [9] It is believed that RYMV has begun to spread since the introduction of the exotic rice ( Oryza sativa ) from Asia into the African continent. [3] Indigenous rices that are from the African area tend to be more tolerant of the virus. [3] The natural host of the virus tends to remain in the Oryzeae tribe of plants. [4] The virus only impacts a few plant species, including certain rice species and wild grasses. [10] The only way for plants to be confirmed of having RYMV is by performing a serological test. [1]
Younger seedlings (3–4 leaf growth stage) are the most susceptible – older plants generally exhibit less obvious foliar symptoms and less stunting than younger siblings. Symptoms appear initially as yellow-green linear spots on the base of the youngest leaves. [11] As the infection grows the spots expand parallel to leaf veins and appear as yellow or orange streaks; these can vary in width, but can be continuous up to 10 cm. [11]
Affected plants have yellow or orange leaves at the early stage of the crop. In severe cases, leaves roll up and dry. Other symptoms are stunting, reduced tillering and poor panicle filling. This results in low or no seed production and poor grain quality. [9]
RYMV located in the rice husks in the plants. [12] The virus is transmissible by animals, by wind-mediated leaf contact, and by abiotic factors (e.g. irrigation water). [8] It can be transmitted by leaf beetles or rats, [4] or from plant to plant through leaf debris, empty rice spikelets, intertwining roots, leaf contact, rice stubble, contaminated hands, and from closely spaced plants. [12] This virus is not seed-borne, nor is it transmitted by nematodes. Long-horned grasshoppers ( Conocephalus ) were found to be a possible vector of RYMV in Uganda. [8]
A few rice cultivars exhibit a high resistance to RYMV characterized by an absence of symptoms and no viral detection. The inheritance of this high resistance is recessive. The resistance gene RYMV1 was identified as an eIF(iso)4G gene. Four rymv1 resistance alleles have been characterized, one in O. sativa (rymv1-2) and three in O. glaberrima cultivars (rymv1-3, rymv1-4, rymv1-5). [13] Resistance of rymv1–3 is caused by a deletion of codons 322–324 in the same domain of eIF(iso)4G. [14]
Resistant and tolerant varieties are available. [9] [15] [16]
Using nursery sites which haven't been infected previously or direct sowing in the field can also help prevent the spread of the virus. [17]
CABI recommends planting the crop as early as possible can avoid the peak period of insect vectors of the virus. In addition, synchronising the planting in different fields can prevent the virus from spreading to younger crops. [11]
Maintaining weeds to control other hosts of the virus and clearing bushes around fields to control breeding sites for insect vectors can also prevent RYMV spread. [15] [17] [18]
Sanitation procedures can reduce the spread of RYMV. CABI recommends cleaning weeds from irrigation canals and around rice fields, especially during the off season, to remove the virus and its insect vectors will remove the virus and insect vectors. [11] Cleaning of farm machinery can reduce spread prevent mechanical spread. This also applies to cleaning any farm machinery after each use. [11] [17]
RYMV will completely kill susceptible varieties; if detected, removing infected plants and destroying them can prevent further spread. It has also been recommended by CABI to reduce the application of fertiliser on infected plants. [11]
There are no chemical control methods to directly stop the spread of RYMV. However, there are available insecticides to control vectors of the virus in some countries; [9] [18] suitable chemicals vary depending on country specific guidelines.
As of 2019 [update] RYMV is still considered an "emerging" disease because there is still a great deal of range expansion ongoing and expected in the future. [5]
This article incorporates text from a free content work. Licensed under CC-BY-SA( license statement/permission ). Text taken from Plantwise Factsheets for Farmers: Resistant rice against rice yellow mottle virus , Jubilant JN Mwangi, Edith D. Kija Mariam I. Mziray, CABI.
This article incorporates text from a free content work. Licensed under CC-BY-SA( license statement/permission ). Text taken from PMDG: Green List - Rice Yellow Mottle Virus , Plantwise, CABI.
This article incorporates text from a free content work. Licensed under CC-BY-SA( license statement/permission ). Text taken from Plantwise Factsheets for Farmers: Rice yellow mottle (Ikivejuru) , Joelle Kajuga, Germain Nkima, CABI.
This article incorporates text from a free content work. Licensed under CC-BY-SA( license statement/permission ). Text taken from PMDG: Rice Yellow Mottle virus - Rwanda , J. Chrysostome Muhigirwa & Germain Nkima, CABI.
This article incorporates text from a free content work. Licensed under CC-BY-SA( license statement/permission ). Text taken from PMDG: Rice Yellow Mottle Virus - Malawi , Chilasa S.L, J.I.G. Masangwa, Shaibu Y.A., CABI.
This article incorporates text from a free content work. Licensed under CC-BY-SA( license statement/permission ). Text taken from PMDG: Rice Yellow Mottle Virus - Ghana , E. Moses, F. C. Brentu & F.A. Nyarko, CABI.
Helicoverpa armigera is a species of Lepidoptera in the family Noctuidae. It is known as the cotton bollworm, corn earworm, Old World (African) bollworm, or scarce bordered straw. The larvae feed on a wide range of plants, including many important cultivated crops. It is a major pest in cotton and one of the most polyphagous and cosmopolitan pest species. It should not be confused with the similarly named larva of the related species Helicoverpa zea.
Cochliobolus miyabeanus is a fungus that causes brown spot disease in rice.
Verticillium albo-atrum is a plant pathogen with many hosts.
Mycosphaerella henningsii is a fungal plant pathogen that causes Brown leaf spot (BLS) in cassava).Part
Sarocladium oryzae (Sawada) is a plant pathogen causing the Sheath rot disease of rice and Bamboo blight of Bambusoideae spp. in Asia.
Colletotrichum orbiculare is a plant pathogen of melons and cucumber. It causes the disease anthracnose that can effect curcubits causing lesions on various parts of the plant. It can effect cucumbers, melon, squash, watermelon and pumpkin, especially when the weather is rainy, humid and warm. It can be transmitted by seed as well as soil and survive between crops. It is also spread by feeding cucumber beetles, splashing water, tools and workers. Efforts to control the fungus include the practice of rotating cucurbits out for a 2-year period, planting cultivars with resistance, burning infected crops and careful control of weeds. Chemical control measures are also available.
Colletotrichum truncatum is a fungal species and plant pathogen on soybeans.
Colletotrichum sublineola is a plant pathogen that causes anthracnose in wild rice and sorghum
Colletotrichum musae is a plant pathogen primarily affecting the genus Musa, which includes bananas and plantains. It is best known as a cause of anthracnose indicating ripeness on bananas.
Cassava mosaic virus is the common name used to refer to any of eleven different species of plant pathogenic virus in the genus Begomovirus. African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV), and South African cassava mosaic virus (SACMV) are distinct species of circular single-stranded DNA viruses which are transmitted by whiteflies and primarily infect cassava plants; these have thus far only been reported from Africa. Related species of viruses are found in India and neighbouring islands, though cassava is cultivated in Latin America as well as Southeast Asia. Nine species of cassava-infecting geminiviruses have been identified between Africa and India based on genomic sequencing and phylogenetic analysis. This number is likely to grow due to a high rate of natural transformation associated with CMV.
Groundnut rosette virus (GRV) is a peanut pathogenic virus found in Sub-Saharan Africa. It is transmitted between plants by insect vectors such as the groundnut aphid.
Tobacco necrosis virus A (TNV) is a plant pathogenic virus of the family Tombusviridae.
Strawberry vein banding virus (SVBV) is a plant pathogenic virus and a member of the family Caulimoviridae.
Sweet potato mild mottle virus (SPMMV) is a plant pathogenic virus of the family Potyviridae.
Leucinodes orbonalis, the eggplant fruit and shoot borer or brinjal fruit and shoot borer, is a moth species in the genus Leucinodes described by Achille Guenée in 1854. Its native distribution is in the tropical and subtropical parts of Australia and Asia, where it is recorded from Pakistan, Nepal, India, including the Andaman Islands, Sri Lanka, Bangladesh, Myanmar, Laos, Cambodia, Vietnam, Thailand, China, Taiwan, Japan, Malaysia, Singapore, Brunei, the Philippines, and Indonesia (Java). It has also been intercepted from fruit imports in the U.S.A., the Netherlands, Denmark and Great Britain, where it was also reported from the wild. A taxonomic revision of the Leucinodes species of Sub-Saharan Africa concluded that L. orbonalis is currently not present in Africa, and that previous records of this species were misidentifications of previously undescribed species.
Busseola fusca is a species of moth that is also known as the maize stalk borer. It is known from Ethiopia.
Banana Xanthomonas Wilt (BXW), or banana bacterial wilt (BBW) or enset wilt is a bacterial disease caused by Xanthomonas campestris pv. musacearum. After being originally identified on a close relative of banana, Ensete ventricosum, in Ethiopia in the 1960s, BXW emanated in Uganda in 2001 affecting all types of banana cultivars. Since then BXW has been diagnosed in Central and East Africa including banana growing regions of: Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Burundi, and Uganda.
Prostephanus truncatus is commonly referred to as larger grain borer (LGB) with reference to the related Rhyzopertha dominica, which is relatively smaller, and referred to as the lesser grain borer. P. truncatus is about 6 mm (0.24 in) long as compared to 3 mm (0.12 in) long in R. dominica. At optimum conditions of 80% relative humidity and 32 °C (90 °F), and available food, P. truncatus completes its lifecycle within 27 days. It is a serious pest of dried grains, especially maize and dried cassava in West Africa. This beetle is believed to have been introduced into West Africa through food aid from America. It reached Africa through Tanzania in the early 1970s.
Maize lethal necrosis disease is a viral disease affecting maize (corn) predominantly in East Africa, Southeast Asia and South America, which was recognised in 2010. It is caused by simultaneous infection with two viruses, MCMoV and any of several Potyviridae.
Cocoa necrosis virus (CoNV) is a plant pathogenic virus of the genus nepovirus that infects Theobroma cacao en natura causing cacao necrosis disease. CoNV is considered synonymous with Strain S of cacao swollen shoot virus. Unlike Cacao swollen shoot virus, it is not transmitted by mealybugs nor vectored by aphids, beetles, or leafhoppers that also commonly infest cacao. It is serologically, distantly related to Tomato black ring virus and very distantly related to Grapevine chrome mosaic virus.
Key examples of viruses that are responsible for well-studied emerging diseases are ... sobemoviruses such as rice yellow mottle virus106.