Prevalence of Rice Yellow Mottle Virus (RYMV) on Rice Plants Grown in Selected Farms in Ogun State: Preliminary Results

Abstract

Incidence of Rice yellow mottle virus (RYMV) on rice plants (ofada) grown in two local government areas (LGAs) of Ogun State had been evaluated during a two year field survey. Six month old rice plants were observed for symptom expression and leaf samples collected for serological indexing. Of the 60 leaf samples collected for both years, 96.7 % were presented with symptoms and severity ranged from 1 to 5 in 2012. Symptoms of brown blotches, chlorosis, leaf yellowing and necrosis were observed on rice plants from which samples were collected at Ewekoro LGA. Similar symptoms were also seen on rice plants at Obafemi Owode. Disease incidence due to RYMV was 7.7 % at Ewekoro in 2012 while it was 13.3 % for plants surveyed at Obafemi owode in the same year. In 2013, incidence varied from 30.0 to 90.0 % and the higher incidence was observed on samples at Obafemi owode. Serodiagnosis of Grasshopper (Zonocerus variegatus) and Locust (Locusta migratoides) trapped at the rice fields during the survey revealed that they were not implicated in virus transmission as their absorbance values at spectrophotometric wavelength of 405 nm were not up to one and half times the values of the healthy controls.Keywords: rice, ELISA, incidence, virus symptom, survey Correspondence: sdara@hotmail.com IntroductionWith increase in world population, there is emphasis on increasing level of food production, among which is rice. Rice (Oryza spp.) is grown widely in many parts of the world. It is the major food source for about 40 % of the world's human population (Ortiz, 2011) Production of rice in Nigeria is being threatened by infections from various pathogens such as Rice yellow mottle virus (RYMV) and others such as Maize streak virus (MSV) (Alegbejo, 2013). The virus, Rice yellow mottle virus (RYMV) is a non-enveloped isometric virus belonging to the genus Sobemovirus. Its particle size is 25 nm in diameter with conspicuous capsomere arrangement. The biochemical properties of RYMV include its virions containing 23 % nucleic acid, 77 % protein and 0 % lipid. It is a RNA virus, single stranded and its total genome size is 4.2 kb (kilobase).

Assessment of Korean rice lines for their reaction to rice yellow mottle virus in Ghana

“…Partially and highly resistant varieties have been identified, but currently the disease is not controlled adequately, and its incidence continues to increase in Africa ( Kouassi et al., 2005 ; Salaudeen 2014 ). In Nigeria, an increase in the incidence of the disease was observed in addition to increase in severity from 30 to 90 % after one year period ( Odedara et al., 2016 ). No variety is yet commercially available that has both high resistance and other desirable agronomic traits ( Kouassi et al., 2005 ; Suvi et al., 2018 ).…”

Evaluating the incidence and severity of rice yellow mottle virus and maize streak virus on rice (Oryza sativa L.) and associated insects in the Federal Capital Territory, Abuja, Nigeria

“…The high and consistent rainfall recorded in 2019 rice growing season could have been responsible for the low vector population and absence of infection, as the vectors would have been washed away. The two viruses that were selected for detection have been reported in other West African countries as well as some parts of Nigeria (Sere et al, 2008;Banwo et al, 2004;Alegbejo, 2013;Oludare et al, 2015;Odedara et al, 2016;Onasanya et al, 2011). Odedara (2016) reported from surveys carried out in Ogun State in 2012 the presence of RYMV in 7.7% of leaf samples collected and tested from Ewekoro Local Government Area (LGA) and 13.3% from leaf samples collected and tested from Obafemi Owode LGA.…”

“…The two viruses that were selected for detection have been reported in other West African countries as well as some parts of Nigeria (Sere et al, 2008;Banwo et al, 2004;Alegbejo, 2013;Oludare et al, 2015;Odedara et al, 2016;Onasanya et al, 2011). Odedara (2016) reported from surveys carried out in Ogun State in 2012 the presence of RYMV in 7.7% of leaf samples collected and tested from Ewekoro Local Government Area (LGA) and 13.3% from leaf samples collected and tested from Obafemi Owode LGA. Further survey in 2013 recorded the presence of RYMV in 30.0% of leaf samples collected and tested in Ewekoro LGA, while Obafemi Owode recorded 90.0%.…”

“…In Nigeria, RYMV has being the most prevalent causing a major challenge in rice production since 1976 when it was first reported (Rossel et al, 1982). Earlier studies done in the Southern part of Nigeria show the incidence of RYMV is up to 70% (Onasanya et al, 2011;Odedara et al, 2016). The adverse effect of viruses on rice production in Nigeria as well as limited information and literature on rice viruses in Abuja, necessitated this research with the objective to evaluate the incidence and severity of RYMV and MSV infecting rice and identify insects associated with rice production in Abuja.…”

Inhibition of root growth as mode of action of two rice yellow mottle virus pathotypes isolated in Mali

“…However, the ability of pathogens to overcome resistant genes in crops compromised the durability of these resistances (Ochola and Tusiime, 2011). West and Central Africa have a high pathogenic diversity (Abo et al, 1998;N'Guessan et al, 2001;Oludare et al, 2016;Odedara et al, 2016) and this genetic diversity occurring among RYMV populations seems to present a big challenge for breeding rice for durable resistance to plant virus (Munganyinka et al, 2016). An hypervirulent pathotype of Rice Yellow Mottle Virus was identified in West and Central Africa (Hebrad et al, 2018;Pidon et al, 2017).…”