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Grass pea ( Lathyrus sativus L.) is a legume crop known to be an excellent source of protein, tolerant to drought, waterlogging, and salinity. The crop is used as an alternative source of protein to reduce malnutrition for resource-poor people and farmers leaving in marginal areas. However, due to the presence of a neurotoxin that causes lathyrism in the crop, it has been neglected and underutilized. As a necessary first step towards, therefore, this investigation was undertaken to assess the genetic diversity and population structure that existed within grass pea accessions collected from the North-Western part of Ethiopia using simple sequence repeat markers. Twenty-five grass pea accessions collected from the Ethiopian Biodiversity Institute were planted at the College of Agricultural Science, Ebonyi State University, Nigeria. The genomic DNA was extracted using Quick-DNA™ ZR Plant/Seed Miniprep Kit and amplified by ABI Veriti PCR with 10 pairs of SSR markers in IITA, Ibadan, Nigeria. Out of 10 SSR primers, only eight primers were polymorphic. A total of 41 alleles were detected with an average of 5.13. The Polymorphic information content and gene diversity values ranged from 0.074 to 0.944 with a mean of 0.474 and 0.536 respectively. The largest pairwise genetic distance (0.365) was detected between North Gondar and East Gojam populations. The ФPT (analogs of FST test) estimated through AMOVA were 0.24, 0.20, and 0.05 for within accessions, among regions, and population within regions respectively. The highest genetic differentiation value (76%) resides within accessions followed by 20% among regions. Both population structure and cluster analysis grouped the 25 grass pea accessions into two distinctive subgroups. This grouping pattern indicates the presence of gene flow among geographic regions. In general, the findings of this study indicate that despite few numbers of SSR markers it was possible to detect genetic diversity among grass pea accessions indicating the power of the SSR marker in picking up the existing genetic diversity within the studied accessions.

Sugarcane bacilliform virus (SCBV) is an economically important virus limiting sugarcane production worldwide. Although Ethiopia is a major sugarcane producer, and virus-like symptoms are frequently observed in sugarcane fields, there is a complete lack of information as to the occurrence, distribution and molecular properties of SCBV. This study was aimed to identify and characterize SCBV isolates in Ethiopia using molecular methods. Out of 292 leaf samples collected and tested by PCR, 76 samples (26% incidence level) were found SCBV-positive. Nucleotide sequence analysis results showed that three Ethiopian isolates (SCBV-EtS3, SCBV-EtS6 and SCBV-EtC10) shared high level of nucleotide identity (99.5-100%) among themselves and with SCBV isolates from China (accession numbers MH037614 and MH037915). Another isolate, SCBV-EtC2, shared maximum identity of 78% with the other three SCBV isolates from Ethiopia and 99.8% with SCBV isolates from China (KM214357 and KM214307). Based on phylogenetic analysis, isolates from Ethiopia were segregated into two different clusters. Isolates SCBV-EtS3, SCBV-EtS6 and SCBV-EtC10 clustered with SCBV-Q group and SCBV-EtC2 with SCBV-H group. This study provides information on the occurrence of SCBV for the first time in Ethiopia and also contributes to the understanding of the genetic diversity of SCBV. Keywords: Caulimoviridae; RNase H, Saccharum spp.; Sugarcane bacilliform virus.

Chickpea chlorotic stunt virus (CpCSV, genus Polerovirus, family Solemoviridae), first reported in Ethiopia in 2006, causes an economically important yellowing and stunting disease in legume crops such as chickpea, faba bean, field pea, and lentil in most production areas of North Africa and Central and West Asia. Disease epidemics have been reported in Ethiopia, Syria, and Tunisia. The virus is transmitted persistently by aphids of the species Aphis craccivora and Acyrthosiphon pisum and naturally infects several legume and non-legume hosts. CpCSV exists as at least two geographic strain groups that differ in their genome sequence and serological and biological properties. In addition, a genetically divergent isolate proposed to be a member of a distinct polerovirus species has been reported from pea and faba bean in China. The ssRNA genome of the Ethiopian isolate has 5900 nucleotides, is encapsidated in isometric particles of ~ 28 nm diameter, and is suggested to have evolved by recombination of cucurbit aphid-borne yellows virus- and soybean dwarf virus-like parents. Moreover, a number of newly reported poleroviruses are suggested to have evolved by recombination between CpCSV and other parental poleroviruses. Identification of sources of resistance and further knowledge on disease epidemiology, including specific strains, vectors, and alternate hosts in different growing areas, are required for devising effective disease management strategies. Modern biotechnology tools such as next-generation sequencing, molecular markers, and agroinoculation-based resistance screening techniques can expedite future research and management efforts. This review addresses various aspects of CpCSV, including its properties, ecology, the disease it causes, management options, and future research perspectives.

Maize lethal necrosis (MLN) is a viral disease caused by a co-infection of maize chlorotic mottle virus (MCMV) and any one of cereal viruses including sugarcane mosaic virus (SCMV), maize dwarf mosaic virus, wheat streak mosaic virus or Johnsongrass mosaic virus. MLN has been identified as the most devastating maize disease that causes the highest yield loss in major maize growing areas in Eastern Africa including Ethiopia. In this study, field assessment, laboratory, and greenhouse experiments were conducted using MCMV and SCMV infected maize residue and infested soil to: (1) assess the role of MLN infected maize residue and infested soil in the transmission of MLN causing viruses, and (2) determine the longevity of the viruses both in the infected maize residue and in the infested soils. Serological detection and back-inoculation test results showed that MCMV was detected and confirmed to be transmitted from infested soil to newly germinated maize seedlings. However, SCMV was neither detected in soil samples from infected fields nor transmitted to maize seedlings. The present study confirmed that MLN infested soil is an essential medium for the survival and spread of MCMV under natural conditions. Under experimental condition, MCMV remained persistent and transmissible up to 6 months to maize planted on MLN infested soil mixed with MLN infected maize residues. Proper management or clearing of crop residues in the field after harvest is necessary to minimize adverse effects of MLN on maize production. Crop rotation is also one of the ways of freeing the soil from MLN disease.

Maize lethal necrosis (MLN) is becoming a great challenge to maize production that threatens food security for most households in East Africa since 2011. MLN in East Africa, including Ethiopia, is caused by co-infection of maize chlorotic mottle virus (MCMV) and any other potyvirus, often sugarcane mosaic virus (SCMV). A greenhouse study was conducted at Ambo Agricultural Research Center to determine the reactions of various maize genotypes to MLN to identify resistant genotypes that can be either utilized in breeding programs or recommended for commercial production. A total of 306 maize genotypes (275 inbred lines and 31 commercial varieties) collected from various research centers and seed companies were evaluated in the greenhouse under artificial MLN inoculation. Weekly MLN severity score, pooled mean of weekly severity score, area under disease progress curve (AUDPC), final disease severity, and disease incidence were used to assess reactions of the maize genotypes to MLN. Double antibody sandwich enzyme-linked immunosorbent assay test showed that only 2% of the highland maize inbred lines were resistant to MLN, whereas none of the lowland and mid-altitude inbred lines were resistant to the disease. Roughly 7%, 16.7%, and 5.5% of the inbred lines from highland, mid-altitude, and lowland maize breeding programs, respectively, showed moderately resistant reactions to MLN. However, higher proportion of the inbred lines from all the breeding programs revealed susceptible to highly susceptible reactions. Most of the maize varieties evaluated were infected by MLN with different levels of reactions that ranged from moderately susceptible to highly susceptible. Only two highland varieties (Wenchi and Kolba) showed moderately resistant reaction. In general, while most of the maize genotypes evaluated were infected by the viruses, considerable number of inbred lines and varieties showed resistant/tolerant reactions to MLN. Inbred lines that showed good level of resistance to the disease can be used as sources of desirable genes in maize breeding programs, while MLN resistant or tolerant varieties could be recommended for extensive commercial production.

One hundred sixty-five advanced lines were subjected to marker-assisted selection using Cleaved amplified polymorphic sequence-polymerase chain reaction (CAPS-PCR) primer against Barley yellow dwarf (BYD) resistant Yd2 gene. In addition, phenotypic evaluation was employed to screen the advanced lines for multiple disease resistance. Effect of host growth rate and incubation period on BYD development was also assessed. Results of marker PCR showed that Yd2 gene was detected in 96 (58.2%) out of 165 accessions tested. Data on relationships of days to heading (DtH) and BYD symptoms development revealed that barley accessions having shorter DtH (66 days), BYD severity appeared low, and vice versa on accessions having longer DtH (79–83 days). Screening for multiple disease resistance gave interesting results. Among 11 accessions (with Yd2) selected as the best for multiple diseases, 6 accessions [Chelia local, 4304–2(2), 4818(1.3), 1822–1(1), 1831–2-2(2), and 4915–1(1.2)] were highly resistant to leaf rust and net blotch, while other five lines had moderately resistant reaction. Study on the relationship of host resistance and incubation period showed that BYDV was detectable 5 days earlier in susceptible than in resistant lines. This can be used as an alternative method in preliminary screening of large number of genotypes against BYDV. From this study, it was evident that the identified resistant genotypes are a good resource for barley improvement program targeting BYDV and other important foliar pathogens. Barley breeders are encouraged to take advantage of this opportunity in producing multi-disease resistant barley genotypes in an agronomically enhanced genetic background in the country and beyond.

Three tannia (Xanthosoma sp.) plants showing mosaic, mottling and vein chlorosis symptoms were observed in Buikwe district, Uganda. Next generation sequencing (NGS) of RNA extracted from the three plants revealed the presence of Cucumber mosaic virus (CMV). The complete genome sequence of this isolate, designated CMV-Xa, was assembled and sequence analyses based on the three genomic RNAs revealed that CMV–Xa belongs to subgroup IB. This is the first report of CMV infecting Xanthosoma sp. and also the first CMV isolate from subgroup IB detected from sub-Saharan Africa.

Maize (Zea mays L.) is host for more than 50 virus species worldwide with Maize streak virus (MSV) (genus Mastrevirus) causing significant yield losses in Africa. A survey for viruses infecting maize was conducted in major growing regions of Ethiopia. To test for DNA viruses, in particular mastreviruses, rolling circle amplification was performed for the analysis of virus composition in assayed samples. Following the analysis of the entire virus genomes, three genetic groups, each representing distinct virus species, were identified. The first group was almost identical with the A-strain of MSV. The next sequence-cluster shared 96-98% identity with isolates of Maize streak reunion virus (MSRV) confirming the presence of this virus also in continental East Africa. Sequence analysis of additional virus genomes (each 2846 nt) in length revealed only a limited 70-71% nt identity with MSRV isolates and an even lower identity ( 64%) with sequences of mastreviruses described elsewhere. Our analysis suggests a novel virus species, which is tentatively named maize streak dwarfing virus (MSDV). The pairwise comparison of capsid protein and replication-associated protein (Rep) of the novel species revealed a limited identity of 63% and 68% with the respective protein sequences of MSRV. The incidence of the virus species in the maize regions of Ethiopia was studied across 89 samples collected during four growing seasons. PCR analysis with general and specific mastrevirus primers showed that MSV is the most incident virus (39.3%) followed by MSRV (14.6%) and MSDV (12.4%). Identification of three different mastrevirus species in a confined geographical location on the same host, maize, is unprecedented, and suggests that Ethiopia may be one of the potential hot spots for diversity of maize-infecting mastreviruses.

Chickpea chlorotic stunt virus (CpCSV, genus Polerovirus, family Solemoviridae), first reported in Ethiopia in 2006, causes an economically important yellowing and stunting disease in legume crops such as chickpea, faba bean, field pea, and lentil in most production areas of North Africa and Central and West Asia. Disease epidemics have been reported in Ethiopia, Syria, and Tunisia. The virus is transmitted persistently by aphids of the species Aphis craccivora and Acyrthosiphon pisum and naturally infects several legume and non-legume hosts. CpCSV exists as at least two geographic strain groups that differ in their genome sequence and serological and biological properties. In addition, a genetically divergent isolate proposed to be a member of a distinct polerovirus species has been reported from pea and faba bean in China. The ssRNA genome of the Ethiopian isolate has 5900 nucleotides, is encapsidated in isometric particles of ~ 28 nm diameter, and is suggested to have evolved by recombination of cucurbit aphid-borne yellows virus- and soybean dwarf virus-like parents. Moreover, a number of newly reported poleroviruses are suggested to have evolved by recombination between CpCSV and other parental poleroviruses. Identification of sources of resistance and further knowledge on disease epidemiology, including specific strains, vectors, and alternate hosts in different growing areas, are required for devising effective disease management strategies. Modern biotechnology tools such as next-generation sequencing, molecular markers, and agroinoculation-based resistance screening techniques can expedite future research and management efforts. This review addresses various aspects of CpCSV, including its properties, ecology, the disease it causes, management options, and future research perspectives.

Garlic is one of the most crucial Allium vegetables used as seasoning of foods. It has a lot of benefits from the medicinal and nutritional point of view; however, its production is highly constrained by both biotic and abiotic challenges. Among these, viral infections are the most prevalent factors affecting crop productivity around the globe. This experiment was conducted on eleven selected garlic accessions and three improved varieties collected from different garlic growing agro-climatic regions of Ethiopia. This study aimed to identify and characterize the isolated garlic virus using the coat protein (CP) gene and further determine their phylogenetic relatedness. RNA was extracted from fresh young leaves, thirteen days old seedlings, which showed yellowing, mosaic, and stunting symptoms. Pairwise molecular diversity for CP nucleotide and amino acid sequences were calculated using MEGA5. Maximum Likelihood tree of CP nucleotide sequence data of Allexivirus and Potyvirus were conducted using PhyML, while a neighbor-joining tree was constructed for the amino acid sequence data using MEGA5. From the result, five garlic viruses were identified viz. Garlic virus C (78.6 %), Garlic virus D (64.3 %), Garlic virus X (78.6 %), Onion yellow dwarf virus (OYDV) (100%), and Leek yellow stripe virus (LYSV) (78.6 %). The study revealed the presence of complex mixtures of viruses with 42.9 % of the samples had co-infected with a species complex of Garlic virus C, Garlic virus D, Garlic virus X, OYDV, and LYSV. Pairwise comparisons of the isolated Potyviruses and Allexiviruses species revealed high identity with that of the known members of their respected species. As an exception, less within species identity was observed among Garlic virus C isolates as compared with that of the known members of the species. Finally, our results highlighted the need for stepping up a working framework to establish virus-free garlic planting material exchange in the country which could result in the reduction of viral gene flow across the country.Author SummaryGarlic viruses are the most devastating disease since garlic is the most vulnerable crop due to their vegetative nature of propagation. Currently, the garlic viruses are the aforementioned production constraint in Ethiopia. However, so far very little is known on the identification, diversity, and dissemination of garlic infecting viruses in the country. Here we explore the prevalence, genetic diversity, and the presence of mixed infection of garlic viruses in Ethiopia using next generation sequencing platform. Analysis of nucleotide and amino acid sequences of coat protein genes from infected samples revealed the association of three species from Allexivirus and two species from Potyvirus in a complex mixture. Ultimately the article concludes there is high time to set up a working framework to establish garlic free planting material exchange platform which could result in a reduction of viral gene flow across the country.

A survey to identify the distribution of virus diseases of maize was made in major maize growing regions of Ethiopia. Four surveys were conducted between 2015 and 2017. A total of 284 maize fields have been surveyed, of which 846 leaf samples with virus like disease symptoms were collected from 191 fields. There were no symptoms indicating for virus presence in maize grown in 93 fields which were exempted from sampling, while in contrast up to 100% disease incidence was recorded in maize grown in the Benishangul-Gumuz, Oromia and South Nations, Nationalities and People (SNNP) regions. Symptoms varied in maize ranging from the most common mosaic and streak to severe leaf mottling and necrosis as well as stunting and pre-mature plant death. Double or triple antibody sandwich (DAS or TAS) enzyme-linked immuno-sorbent assay (ELISA) to test for eight common maize viruses such as Maize chlorotic mottle virus (MCMV), Sugarcane mosaic virus (SCMV), Maize streak virus (MSV), Maize dwarf mosaic virus (MDMV), Maize mosaic virus (MMV), Maize stripe virus (MSpV), Wheat streak mosaic virus (WSMV) and Johnsongrass mosaic virus (JGMV) confirmed the presence of MCMV, SCMV and MSV in the leaf samples. Single or mixed infections with MCMV and SCMV frequently occurred and triple infections of MCMV, SCMV and MSV were found in 1% of samples from SNNP region. Sequence analysis of the coat protein genes of randomly selected seropositive samples of the three viruses showed little variability within the studied isolates and those retrieved from the GenBank. Our results indicated maize lethal necrosis disease (MLND) caused by MCMV and SCMV co-infection was the most important disease in SNNP and Oromia while maize streak disease was the predominant virus infecting maize in Benishangul-Gumuz.

Electron microscopy of leaf samples displaying streak symptoms from enset (Ensete ventricosum), a banana‐like plant widely cultivated in Ethiopia, showed the presence of bacilliform shaped virions as known for badnaviruses. DNA extracts subjected to rolling circle amplification (RCA), polymerase chain reaction (PCR) and cloning and sequence analysis revealed that the virus has a circular double‐stranded DNA genome of 7,163 nucleotides encoding predicted proteins of 21.5 kDa, 14.5 kDa and 202.5 kDa, a genome organization known for badnaviruses. The virus is phylogenetically most closely related to Sugarcane bacilliform Guadeloupe D virus with a nucleotide sequence identity of 77.2% at the conserved RT/RNase‐H region and 73.6% for the whole genome. Following the current species demarcation criteria, the virus should be considered as an isolate of a new species in the genus Badnavirus for which the name Enset leaf streak virus (ELSV) is suggested. Leaf samples from enset and banana were screened using virus‐specific primers, and ELSV was detected in six of 40 enset but not found in any of 61 banana samples. On the other hand, Banana streak OL virus (BSOLV) was detected from the majority (60%) of symptomatic banana samples but not from enset samples. This paper reports the first full‐genome sequence of a putative new badnavirus species infecting plants in the genus Ensete. In addition, this is the first report of the occurrence of BSOLV in Ethiopia.

The yellow dwarf (YD) disease complex epidemics in cultivated cereals grown in a specific period of the year mainly depend on the presence of potential reservoir alternative hosts harbouring both the viruses and the vectors over the off‐season and serve as a source of inoculum in subsequent cropping season, further spread being supported by efficient aphid vectors. As such, an extensive and intensive exploration to generate base line information on the identity and prevalence of YD viruses [barley yellow dwarf virus (BYDV)‐PAV, BYDV‐MAV and BYDV‐SGV; cereal yellow dwarf virus (CYDV)‐RPV; and maize yellow dwarf virus (MYDV)‐RMV] on wild annual and perennial grasses and forage cereals alternative hosts was conducted consecutively during 2013–2015 main‐ and short‐rainy seasons in cereals growing belts of Ethiopia. Random sampling was employed to collect the samples that were tested by the tissue blot immunoassay (TBIA) to identify the YDVs associated with the hosts using a battery of virus‐specific polyclonal antibodies. Of 13,604 samples analysed, YDVs were detected in 392 (2.9%) samples, which consisted of various wild grasses, forage cereals and three cultivated crops. YDVs were identified from at least 26 grass species and forage cereals, some of them are new records, and some are previously documented hosts. To our knowledge, this is the first report of YDV infection of Andropogon abyssinicus (FresenR.Br. ex Fresen.) (BYDV‐PAV), Avena abyssinica Hochst (BYDV‐PAV), Bromus pectinatus Thunb. (BYDV‐PAV and BYDV‐MAV), Eragrostis tef (Zuccagni) Trotter (BYDV‐PAV), Eragrostis sp. (BYDV‐PAV), Hyparrhenia anthistrioides Stapf. (BYDV‐PAV), Panicum coloratum L. (BYDV‐PAV), Polypogon monspeliensis (L.) Desf. (BYDV‐PAV), Setaria pumila (Poir.) Roem & Schult (BYDV‐PAV, BYDV‐SGV and MYDV‐RMV), Setaria australiensis (Scribn. & Merrill) Vickery (BYDV‐PAV, BYDV‐MAV and CYDV‐RPV) and Snowdenia polystachya (Fresen.) Pilg (BYDV‐PAV, BYDV‐MAV, BYDV‐SGV, CYDV‐RPV and MYDV‐RMV).

Maize Lethal Necrosis Disease (MLND) develops from synergistic co-infection by Sugarcane mosaic virus and Maize chlorotic mottle virus. The disease causes symptoms ranging from leaf tissue mottling and malformed ears to premature plant death. Information on the diversity and transmission of those viruses are limited in Ethiopia. No attempts were made to characterize and identify SCMV and MCMV strains of Oromia and Benishangul-Gumuz regions. The aim of this research was to study MLND responsible viruses via serological and molecular techniques. A total of 174 symptomatic maize leaf samples were collected. Using Double Antibody Sandwich-ELISA (DAS-ELISA), 43 samples showed strong reaction for MCMV antibody and only 14 samples were clearly positive for SCMV. Reverse transcriptase polymerase chain reaction (RT-PCR) technique revealed the presence of MCMV and SCMV in most samples. Analysis of the genetic diversity of MCMV and SCMV by sequencing the coat protein of all isolates shows strong homology with previous East African isolates deposited in the GenBank. The phylogenetic analysis indicated that the virus isolates are highly similar with each other. In conclusion, this study unequivocally confirmed the association of MCMV and SCMV with MLND in the investigated areas and for the first time provided information on the genetic variability by sequence analysis of several Ethiopian samples. Since the risk posed by MLND in the investigated area is high, there is an urgent need for developing integrated management options for controlling the disease.

Little information exists on the type and incidence of viruses infecting garlic (Allium sativum L) in Ethiopia. Attempts were made to identify the viruses using molecular techniques from 95 composite leaf samples collected from 44 farmers’ fields and 51 germplasm accessions. Reverse transcription (RT-) PCR using genus and/or virus specific primers was used to amplify partial genome sequences of potyviruses, allexiviruses, carlaviruses and a tospovirus followed by sequencing of PCR products. Results indicated that ~73.7% of the samples are infected with at least one virus. Onion yellow dwarf virus (OYDV, genus Potyvirus, family Potyviridae) is the most common virus detected followed by Garlic virus C (genus Allexivirus) and Shallot latent virus (SLV, genus Carlavirus). Other viruses detected at lower frequency include Garlic virus X and Garlic virus D (genus Allexivirus), Leek yellow stripe virus (genus Potyvirus) and Iris yellow spot virus (IYSV, genus Tospovirus). Mixed infection of two or more viruses was detected in 65.7% of the samples. Phylogenetic analysis suggested that the different viruses may have been introduced to Ethiopia from Europe or Asia. This is the first report of Garlic virus X, Garlic virus D, IYSV and SLV in garlic in Ethiopia. The high incidence of OYDV and IYSV which cause severe yield loss alone or in mixed infection with allexiviruses and carlaviruses is a cause of concern to growers.

In all, 70 of 296 leaf samples (23.6%) collected from faba bean (Vicia faba) plants showing leaf yellowing and stunting in Ethiopia gave nanovirus-positive reactions when studied by triple-antibody sandwich enzyme-linked immunosorbent assay using broad-spectrum monoclonal antibodies (MAbs) specific to nanoviruses. Further analysis of these samples with seven discriminating MAbs revealed contrasting epitope profiles that were categorized into roughly three serogroups, designated A, B, and C. Serogroup A was found in 89% of the nanovirus-positive samples whereas serogroups B and C were infrequently encountered. Sequence analysis of DNA-S and DNA-U1 of serogroup A, B, and C isolates suggested that each represents a distinct nanovirus species. Serogroup A comprised isolates of Faba bean necrotic stunt virus reported earlier only from Ethiopia and Morocco. The DNA-R, -S, -U1, and -U2 sequences of a serogroup B isolate closely resembled those of Faba bean necrotic yellows virus, providing first molecular evidence for its occurrence in Ethiopia. Sequence analysis of the eight genomic DNAs of a representative serogroup C isolate (Eth-231) showed that it shared overall nucleotide and amino acid sequence identities of only ≤70 and ≤74%, respectively, with other nanoviruses. This suggests that Eth-231 represents a new nanovirus species, for which the name faba bean yellow leaf virus is proposed.

Four hundred thirteen fields in five major maize growing regions of Ethiopia were surveyed to determine the prevalence, intensity and distribution of maize lethal necrosis (MLN) disease, and its associations with different maize cropping systems and cultural practices. The disease was most prevalent in South Nation, Nationality and Peoples (SNNP) region with 66.67% prevalence followed by Oromia region that had a prevalence of 65.62%. Similarly, MLN disease intensity and distribution varied among the regions surveyed, cropping systems and cultural practices used by the farmers. The associations of MLN disease intensity with independent variables were analyzed using logistic regression. Region, altitude, cropping season, cropping system, variety, insect vector, planting month and cropping year were significantly associated with high disease intensity of MLN in a multiple variable model. SNNP, Oromia and Benishangul-Gumuz regions, maize cultivated at altitudes of 900–1600 and 1700–2000 m.a.s.l, mono-cropping, presence of insect vectors, medium and high weed density and the 2015, 2016 and 2017 cropping years had a significant association with MLN disease epidemics. This study indicated that MLN disease is a major maize production constraint in Ethiopia. The findings suggested that planting maize at the beginning of the main rainy season, proper weed management and crop rotation practices can minimize the negative impact of the MLN disease until resistant maize genotypes are developed and distributed to the farmers.

Hypovirulence of phytopathogenic fungi are often conferred by mycovirus(es) infections and for this reason many mycoviruses have been characterized, contributing to a better understanding of virus diversity. In this study, three strains of Fusarium head blight fungus (Fusarium boothii) were isolated from Ethiopian wheats as dsRNA-carrying strains: hypovirulent Ep-BL13 (&gt, 10, 3 and 2.5 kbp dsRNAs), and virulent Ep-BL14 and Ep-N28 (3 kbp dsRNA each) strains. The 3 kbp-dsRNAs shared 98% nucleotide identity and have single ORFs encoding a replicase when applied to mitochondrial codon usage. Phylogenetic analysis revealed these were strains of a new species termed Fusarium boothii mitovirus 1 in the genus Mitovirus. The largest and smallest dsRNAs in Ep-BL13 appeared to possess single ORFs and the smaller was originated from the larger by removal of its most middle part. The large dsRNA encoded a replicase sharing the highest amino acid identity (35%) with that of Botrytis virus F, the sole member of the family Gammaflexiviridae. Given that the phylogenetic placement, large genome size, simple genomic and unusual 3&prime, terminal RNA structures were far different from members in the order Tymovirales, the virus termed Fusarium boothii large flexivirus 1 may form a novel genus and family under the order.

Taro (

The badnavirus taro bacilliform virus (TaBV) has been reported to infect taro (Colocasia esculenta L.) and other edible aroids in several South Pacific island countries, but there are no published reports from Australia. Using PCR and RCA, we identified and characterized an Australian TaBV isolate. A terminally redundant cloned copy of the TaBV genome was generated and shown to be infectious in taro following agro-inoculation. This is the first report of TaBV from Australia and also the first report of an infectious clone for this virus.

The complete genome of an Australian isolate of zantedeschia mild mosaic virus (ZaMMV) causing mosaic symptoms on Alocasia sp. (designated ZaMMV-AU) was cloned and sequenced. The genome comprises 9942 nucleotides (excluding the poly-A tail) and encodes a polyprotein of 3167 amino acids. The sequence is most closely related to a previously reported ZaMMV isolate from Taiwan (ZaMMV-TW), with 82 and 86 % identity at the nucleotide and amino acid level, respectively. Unlike the amino acid sequence of ZaMMV-TW, however, ZaMMV-AU does not contain a polyglutamine stretch at the N-terminus of the coat-protein-coding region upstream of the DAG motif. This is the first report of ZaMMV from Australia and from Alocasia sp.

Maize (Zea mays L.) is host for more than 50 virus species worldwide with Maize streak virus (MSV) (genus Mastrevirus) causing significant yield losses in Africa. A survey for viruses infecting maize was conducted in major growing regions of Ethiopia. To test for DNA viruses, in particular mastreviruses, rolling circle amplification was performed for the analysis of virus composition in assayed samples. Following the analysis of the entire virus genomes, three genetic groups, each representing distinct virus species, were identified. The first group was almost identical with the A-strain of MSV. The next sequence-cluster shared 96–98% identity with isolates of Maize streak reunion virus (MSRV) confirming the presence of this virus also in continental East Africa. Sequence analysis of additional virus genomes (each 2846 nt) in length revealed only a limited 70–71% nt identity with MSRV isolates and an even lower identity (

On September 9, 2009, Ethiopia enacted a highly restrictive biosafety law firmly based on precautionary principles as a foundation for its GMO regulation system. Its drafting process, led by the country's Environmental Protection Authority, was judged as biased, focusing only on protecting the environment from perceived risks, giving little attention to potential benefits of GMOs. Many of its provisions are very stringent, exceeding those of Cartagena Protocol on Biosafety, while others cannot be fulfilled by applicants, collectively rendering the emerged biosafety system unworkable. These provisions include requirements for advance informed agreement and rigorous socioeconomic assessment in risk evaluation for all GMO transactions, including contained research use-which requires the head of the competent national authority of the exporting country to take full responsibility for GMO-related information provided-and stringent labeling, insurance and monitoring requirements for all GMO activities. Furthermore, there is no provision to establish an independent national biosafety decision-making body(ies). As a result, foreign technology owners that provide highly demanded technologies like Bt cotton declined to work with Ethiopia. There is a fear that the emerged biosafety system might also continue to suppress domestic genetic engineering research and development. Thus, to benefit from GMOs, Ethiopia has to revise its biosafety system, primarily by making changes to some provisions of the law in a way that balances its diverse interests of conserving biodiversity, protecting the environment and enhancing competition in agricultural and other economic sectors.

The recent reports of the Polerovirus, Maize yellow mosaic virus (MaYMV) infecting sugarcane (Saccharum spp.) and itch grass (Rottboellia cochinchinensis) in Nigeria (Yahaya et al. 2017) and maize in Burkina Faso (Palanga et al. 2017) provided the motivation for this study. To determine the presence of MaYMV or other poleroviruses, we explored a collection of maize samples of local cultivars taken during virus surveys in August 2015 and July 2016 to assess the distribution of maize lethal necrosis disease (MLND) in three major maize cultivation regions of Ethiopia including Benishangul-Gumuz, Oromia, and South Nations, Nationalities, and People (SNNP). The collection comprised 47 leaf samples from symptomatic maize plants showing yellowing, whitish to yellowish stripes, and mosaic symptoms maintained as dried tissues over anhydrous calcium chloride. Total RNA was extracted using an RNA miniprep kit (Epoch Life Science) following the manufacturer’s instructions. RNA from each sample was screened by one-step RT-PCR with the universal polerovirus primer pair Gen 1 and Gen 2, comprising 322 nucleotides of the coat protein gene (Afouda et al. 2017). By RT-PCR, 78 and 71% of the samples collected in 2015 and 2016, respectively, tested positive for MaYMV. Direct sequencing of the amplified DNA fragments in both directions confirmed near identity (≥99% nt identity) of all Ethiopian sequences and shared 98 to 99% identity to the reference sequence of MaYMV (KU248489). The shared identity to another maize infecting polerovirus species, Maize yellow dwarf virus RMV (MYDV-RMV, NC_021484), ranged from 80 to 81%. To assess the genome variability of the Ethiopian MaYMV isolates, three isolates from three different provinces were selected to perform a deep sequencing analysis. Three independent Illumina libraries were prepared from the respective total RNA and were run on an Illumina MiSeq platform as described by Afouda et al. (2017). De novo and mapped based genome assembly was performed with Geneious v 10.2.3 (Biomatters LTD, NZ). The complete genome sequence of MaYMV isolate MV115 from Basha province was determined with 5,642 nt (MF684369), which was assembled from 36,673 of 2,003,892 reads with an average coverage of 1,141.7. Two near full-length genome sequences were determined, one for isolate MV32 from Wolenchiti Province (5,498 nt, MF684367, 1,820 reads of 2,517,898, mean coverage was 61.3) and for isolate MV90 from Dugda Bora Province (5,504 nt, MF684368, 878 reads of 1,925,886, mean coverage was 33.1). All three determined sequences of MaYMV shared 99.6% identity to each other. The complete MaYMV genome sequence (5,642 nt) of the Ethiopian isolate (MF684369) shared 96.8% nt identity with the Chinese isolate (KU248489), 98.2% with the Nigerian isolate (KY684356), and 95.4% with the isolate from Ecuador (KY052793). This first report of MaYMV in Ethiopia provides evidence for its nationwide distribution and the prevalence of a virus that may have occurred in Ethiopia for some time but was overlooked in targeted surveys focusing on MLND and other prominent maize diseases.

A simple and economical enzyme immunoassay technique using a polystyrene Petri dish as the solid support and a substrate mixed with agar to visualize enzymatic activity was developed and standardized for the detection of plant viruses. Reagents were added as drops into circular areas bounded with a hydrophobic cryomarker pen on the inner surface of the Petri dish. After subsequent incubation and washing steps with antiserum and alkaline phosphatase conjugate, the substrate (5-bromo-4-chloro-3-indolyl phosphate and nitroblue tetrazolium) solution was mixed with warm agar and added to the inner Petri dish surface. Distinct dark blue to purple dots were formed on the agar matrix at the sites where the virus was trapped. The technique is tentatively called 'Petri dish-Agar Dot Immunoenzymatic Assay' (PADIA). In addition to substituting the expensive microtitre plate or nitrocellulose membrane with a plastic Petri dish, PADIA consumes 5-10 times less reagents (antiserum and enzyme conjugate) than conventional ...

Etiological studies of a recently emerged bushy top disease of tobacco in Ethiopia indicated that a ~4.5-kb dsRNA from infected plants represents an umbravirus, whereas a smaller band (~0.5 kb) is that of a new satellite RNA. Potato leafroll virus was also consistently associated with the disease. The three agents, whose experimental host ranges are restricted to members of the family Solanaceae, always occurred together in field samples and are transmitted together by the aphid Myzus persicae nicotianae. The umbravirus, which represents a new species, is most closely related to groundnut rosette virus, and the name Ethiopian tobacco bushy top virus is proposed.

Serological analysis of diseased chickpea and faba bean plantings with yellowing and stunting symptoms suggested the occurrence of an unknown or uncommon member of the family Luteoviridae in Ethiopia. Degenerate primers were used for reverse transcriptase-polymerase chain reaction amplification of the viral coat protein (CP) coding region from both chickpea and faba bean samples. Cloning and sequencing of the amplicons yielded nearly identical (96%) nucleotide sequences of a previously unrecognized species of the family Luteoviridae, with a CP amino acid sequence most closely related (identity of approximately 78%) to that of Groundnut rosette assistor virus. The complete genome (5,900 nts) of a faba bean isolate comprised six major open reading frames characteristic of polero-viruses. Of the four aphid species tested, only Aphis craccivora transmitted the virus in a persistent manner. The host range of the virus was confined to a few species of the family Fabaceae. A rabbit antiserum raised against virion preparations cross-reacted unexpectedly with Beet western yellows virus-like viruses. This necessitated the production of murine monoclonal antibodies which, in combination with the polyclonal antiserum, permitted both sensitive and specific detection of the virus in field samples by triple-antibody sandwich, enzyme-linked immunosorbent assay. Because of the characteristic field and greenhouse symptoms in chickpea, the name Chickpea chlorotic stunt virus is proposed for this new member of the genus Polerovirus (family Luteoviridae).

The online version of the original article can be found under doi:10.1007/s00705-009-0548-9.

In 2003, leaf samples from faba bean plants (Vicia faba L.) showing slight growth reductions and yellowing symptoms were collected in a field near Hebenshausen, Hesse, Germany. Some of these samples did not react in triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) with species-specific monoclonal antibodies (Mabs) to either Bean leaf roll virus or Turnip yellows virus, but did react with a broad-spectrum Mab (B-2-5G4) used to detect viruses in the genera Polerovirus and Luteovirus (family Luteoviridae) (1). Since this indicated the occurrence of a hitherto unrecognized polero- or luteovirus in faba bean in Germany, attempts were made to obtain nucleotide sequence information on two of the unknown faba bean isolates using a pair of degenerate primers (S2 [5′-ATCACITTCGGGCCGWSTCTATCAGA-3′] and AS3 [5′-CACGCGTCIACCTATTTIGGRTTITG-3′] [I = inosine]) derived from conserved domains in the capsid protein (CP) genes of several polero- and luteoviruses. Following reverse transcription (RT)-PCR amplification and cloning, the CP gene sequences of two genetically distinct isolates of Soybean dwarf virus (SbDV), a species of the genus Luteovirus, were obtained. To our knowledge, SbDV has not been reported from Germany or Europe but only from Africa, Australia, Japan, and the United States. In the two latter countries, at least two SbDV strain groups, SbDV-Y (for yellowing) and SbDV-D (for dwarfing), are distinguished on the basis of differences in symptomatology, host range, and molecular properties (2–4). On the basis of CP aa sequences, the two faba bean isolates from Hebenshausen differed by 8%, with one (FB1) most similar (>96% identity) to SbDV-D isolates and the other (FB2) closely related (>96%) to SbDV-Y isolates. Similar to observations in Japan (3) and the United States (2), we were able to detect SbDV in numerous samples from red clover (Trifolium pratense) and white clover (T. repens) in Braunschweig using SbDV antibodies (Agdia, Elkhart, IN) in DAS-ELISA. This was confirmed by RT-PCR amplification of CP gene sequences using SbDV-specific primers (SbDVs: 5′-GTCTACCTAAAAATTTCAAAGAATCTG-3′; SbDVas: 5′-CGGACCCGGTTCTCCGTCTA-3′). CP sequence analysis of two SbDV-positive clover samples revealed the presence of a SbDV-D isolate in red clover. However, a white clover plant contained an unusual SbDV isolate that possessed a unique CP, sharing aa sequence identities of approximately 92% with the two faba bean isolates from Germany and only 88.5 to 90.5% with other SbDV isolates. Attempts at aphid transmission of SbDV isolates from clover to faba bean were only successful for the combination Acyrthosiphon pisum and the white clover isolate. No faba bean seedlings became infected when the aphid species Aulacorthum solani and Aphis craccivora were given acquisition access feedings of 48 to 72 h on SbDV-infected white and red clover plants. The sequences determined in this study were deposited in GenBank (Accession Nos. EF466131–EF466134). References: (1) A. D. Abraham et al. Phytopathology 96:437, 2006. (2) V. D. Damsteegt et al. Phytopathology 89:374, 1999. (3) T. Tamada and M. Kojima. No. 179 in: Descriptions of Plant Viruses. Assoc. Appl. Biol. Kew, England, 1977. (4) H. Terauchi et al. Arch. Virol. 146:1885, 2001.

A survey conducted during November 14–23, 1998, to identify viruses infecting chickpea (Cicer arietinum) and lentil (Lens culinaris) crops in the Shewa province of Ethiopia covered 33 chickpea and 32 lentil fields randomly selected. Identity of the viruses present and virus incidence were determined on the basis of laboratory testing of 100 to 200 randomly collected samples in addition to 15 to 20 symptomatic samples from each field. A total of 5,427 lentil and 3,836 chickpea samples were collected and tested for the presence of 12 different viruses by tissue blot immunoassay (1) at the Plant Pathology Laboratory in Debre Zeit Agriculture Research Center, Ethiopia. All antisera were virus specific, including those for beet western yellows virus (BWYV; ATCC PVAS-647) and soybean dwarf virus (SbDV; ATCC PVAS-650). More than 21% of the samples from 5 chickpea fields were infected; the most common virus was BWYV. Also, at least 21% of the samples from 11 lentil fields were virus positive; the most widespread virus was PSbMV. Highest rates of infection: of lentil in a single field, PSbMV in 58.5% of the samples; in a chickpea field, 41.3% of the samples positive for BWYV. Other viruses such as faba bean necrotic yellows nanovirus (FBNYV) and broad bean wilt fabavirus in chickpea and FBNYV, broad bean stain comovirus, bean yellow mosaic potyvirus, and cucumber mosaic cucumovirus in lentil were detected at very low incidence. Reference: (1) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994

Chickpea chlorotic stunt virus (CpCSV), a proposed new member of the genus Polerovirus (family Luteoviridae), has been reported only from Ethiopia. In attempts to determine the geographical distribution and variability of CpCSV, a pair of degenerate primers derived from conserved domains of the luteovirus coat protein (CP) gene was used for RT-PCR analysis of various legume samples originating from five countries and containing unidentified luteoviruses. Sequencing of the amplicons provided evidence for the occurrence of CpCSV also in Egypt, Morocco, Sudan, and Syria. Phylogenetic analysis of the CP nucleotide sequences of 18 samples from the five countries revealed the existence of two geographic groups of CpCSV isolates differing in CP sequences by 8–10%. Group I included isolates from Ethiopia and Sudan, while group II comprised those from Egypt, Morocco and Syria. For distinguishing these two groups, a simple RFLP test using HindIII and/or PvuII for cleavage of CP-gene-derived PCR products was developed. In ELISA and immunoelectron microscopy, however, isolates from these two groups could not be distinguished with rabbit antisera raised against a group-I isolate from Ethiopia (CpCSV-Eth) and a group-II isolate from Syria (CpCSV-Sy). Since none of the ten monoclonal antibodies (MAbs) that had been produced earlier against CpCSV-Eth reacted with group-II isolates, further MAbs were produced. Of the seven MAbs raised against CpCSV-Sy, two reacted only with CpCSV-Sy and two others with both CpCSV-Sy and -Eth. This indicated that there are group I- and II-specific and common (species-specific) epitopes on the CpCSV CP and that the corresponding MAbs are suitable for specific detection and discrimination of CpCSV isolates. Moreover, CpCSV-Sy (group II) caused more severe stunting and yellowing in faba bean than CpCSV-Eth (group I). In conclusion, our data indicate the existence of a geographically associated variation in the molecular, serological and presumably biological properties of CpCSV. peerReviewed