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Of 31 matings between isolates of P. infestans from several countries, six yielded enough progeny for analysis of inheritance of the virulence phenotype. Virulence was determined in vitro after inoculation of detached leaflets of nine differential lines of potato, each carrying a different gene for resistance. Parents of three matings carried an isozyme marker (glucosephosphate isomerase) which allowed the hybridity of most progeny to be confirmed. Apparently non-hybrid progeny from all three matings were probably selfs or apomicts; these were discarded. The inheritance of virulence in two sib-cross and one backcross family was determined. Patterns of inheritance in F1 and F2 indicated the presence of a gene-for-gene interaction in which alleles of a single locus in the pathogen conditioned virulence or avirulence on each differential. Although the hypothesis that avirulence alleles were dominant and virulence alleles were recessive was supported by many of the data, unexpected segregations were obtained. Alternative hypotheses to explain the latter included low aggressiveness in a proportion of the progeny, a second locus inhibiting avirulence in one parent, a different locus in each parent determining avirulence/virulence on one R-gene, and dominance of some alleles determining virulence. Avirulent field isolates appeared to be heterozygous (Avravr) rather than homozygous (ArrAvr) at avirulence loci. A somatic segregation from avirulence to virulence at three avirulence loci was postulated for one parental isolate. Evidence for linkage of these three loci suggested that the observed somatic segregation resulted from mitotic crossing-over. [ABSTRACT FROM AUTHOR]

Common bean is the most important pulse crops worldwide and in Ethiopia for its multipurpose uses. However, common bean production and productivity is mainly constrained by common bacterial blight (CBB) and angular leaf spot (ALS) diseases. Identifying and using resistant common bean genotypes is the best option to reduce the impact of such bacterial and fungal diseases. Field experiments were carried out to evaluate the genetic resistance of 25 common bean genotypes as treatments to CBB and ALS diseases, and agronomic performances at Haramaya and Melkassa, Ethiopia, during the 2019 and 2020 main cropping seasons. The treatments were arranged in a 5 × 5 triple lattice design with three replications. Data on disease intensity, growth, grain yield and yield components were recorded. Analysis of variance indicated significant (p < 0.0001) variations existed among the genotypes for diseases intensity, grain yield and yield components. Eight genotypes, namely DAB-388, DAB-478, DRKDDRB-70, DRKDDRB-81, NUA-225, NUA-517, NUA-536 and NUA-577 attained relatively low disease severity, AUDPC and disease progress rate next to the checks Zoasho (DAB-96) and Gorossa (Biofort large seed-5) to both common bean diseases regardless of locations and seasons. The genotype DAB-525 showed a moderately resistant reaction to both CBB and ALS, and the other genotypes demonstrated variable disease resistance reactions at both locations and in the two cropping years. Similarly, genotypes DAB-388, NUA-225, NUA-517, and NUA-577 relatively executed well for grain yield and yield components at both experimental fields in the 2019 and 2020 main cropping seasons. Disease severity and grain yield variably and negatively associated with reaction groups of genotypes evaluated for reaction CBB and ALS diseases. In the study, resistance to CBB and ALS diseases and good agronomic performing common bean genotypes were identified which could be important for smallholder and commercial bean production in the study area and other similar agro-ecologies in Ethiopia. It is suggested that a large number of common bean accessions should be evaluated in CBB and ALS hot spot agro-ecologies of Ethiopia for more sources of resistance and better agronomic advantages., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

Background: Aspergillus species cause aflatoxin contamination in groundnut kernels, being a health threat in agricultural products and leading to commodity rejection by domestic and international markets. Presence of Aspergillus flavus and A. parasiticus colonizing groundnut in eastern Ethiopia, as well as presence of aflatoxins have been reported, though in this region, no genetic studies have been done of these species in relation to their aflatoxin production., Results: In this study, 145 Aspergillus isolates obtained from groundnut kernels in eastern Ethiopia were genetically fingerprinted using 23 Insertion/Deletion (InDel) markers within the aflatoxin-biosynthesis gene cluster (ABC), identifying 133 ABC genotypes. Eighty-four isolates were analyzed by Ultra-Performance Liquid Chromatography (UPLC) for in vitro aflatoxin production. Analysis of genetic distances based on the approximately 85 kb-ABC by Neighbor Joining (NJ), 3D-Principal Coordinate Analysis (3D-PCoA), and Structure software, clustered the isolates into three main groups as a gradient in their aflatoxin production. Group I, contained 98% A. flavus, including L- and non-producers of sclerotia (NPS), producers of B 1 and B 2 aflatoxins, and most of them collected from the lowland-dry Babile area. Group II was a genetic admixture population of A. flavus (NPS) and A. flavus S morphotype, both low producers of aflatoxins. Group III was primarily represented by A. parasiticus and A. flavus S morphotype isolates both producers of B 1 , B 2 and G 1 , G 2 aflatoxins, and originated from the regions of Darolabu and Gursum. The highest in vitro producer of aflatoxin B 1 was A. flavus NPS N1436 (77.98 μg/mL), and the highest producer of aflatoxin G 1 was A. parasiticus N1348 (50.33 μg/mL), these isolates were from Gursum and Darolabu, respectively., Conclusions: To the best of our knowledge, this is the first study that combined the use of InDel fingerprinting of the ABC and corresponding aflatoxin production capability to describe the genetic diversity of Aspergillus isolates from groundnut in eastern Ethiopia. Three InDel markers, AFLC04, AFLC08 and AFLC19, accounted for the main assignment of individuals to the three Groups; their loci corresponded to aflC (pksA), hypC, and aflW (moxY) genes, respectively. Despite InDels within the ABC being often associated to loss of aflatoxin production, the vast InDel polymorphism observed in the Aspergillus isolates did not completely impaired their aflatoxin production in vitro., (© 2021. The Author(s).)

Sesamia nonagrioides (Lefèbvre) (Lepidoptera: Noctuidae), is a widespread insect pest in Africa, the Middle East, and Europe. However, its pest status varies across its distribution range. It is a major pest of maize in Europe and of sugarcane in Iran. In Africa, it is a major pest of maize in West Africa but not considered as a pest in East Africa. Recent surveys conducted in 2015 recorded S. nonagrioides to be a major pest of sugarcane in Ethiopia and reported the species for the first time in Botswana, outside its known geographic range. The genetic relationship of these records with the previously recorded population of S. nonagrioides was investigated using the cytochrome oxidase subunit I region of the mitochondrial genome. In total, 113 individuals across the geographic range of the species were analyzed and 63 haplotypes were identified. Phylogenetic analysis separated the populations into two clades with no distinct geographic distribution pattern. The genetic differentiation was also not associated with host plants and geographic distances. Results of the molecular analysis revealed the long-time establishment of S. nonagrioides population in Botswana and identified the newly recorded sugarcane population from Ethiopia as part of the wild host population in the country. The phylogeographic patterns observed among population of S. nonagrioides have probably been shaped by Pleistocene's climatic oscillations and geographic range expansions from different refugia with secondary contact and admixture. Possible reasons for the host-plant expansion by the Ethiopian population are discussed.

This study was conducted to assess major Aspergillus species and aflatoxins associated with groundnut seeds and cake in Eastern Ethiopia and evaluate growers' management practices. A total of 160 groundnut seed samples from farmers' stores and 50 groundnut cake samples from cafe and restaurants were collected. Fungal isolation was done from groundnut seed samples. Aspergillus flavus was the dominant species followed by Aspergillus parasiticus. Aflatoxin analyses of groundnut seed samples were performed using ultra performance liquid chromatography; 22.5% and 41.3% of samples were positive, with total aflatoxin concentrations of 786 and 3135 ng g -1 from 2013/2014 and 2014/2015 samples, respectively. The level of specific aflatoxin concentration varied between 0.1 and 2526 ng g -1 for B 2 and B 1 , respectively. Among contaminated samples of groundnut cake, 68% exhibited aflatoxin concentration below 20 ng g -1 , while as high as 158 ng g -1 aflatoxin B 1 was recorded. The study confirms high contamination of groundnut products in East Ethiopia.

Mitochondrial DNA (mtDNA) haplotypes were determined using restriction fragment length polymorphism (RFLP) for P. infestans sampled from 513 foliar lesions of late blight found on potato and tomato in different regions of Ethiopia. Among the four reported mitochondrial haplotypes of Phytophthora infestans, Ia, Ib and IIb were detected in 93 % of the samples analyzed but the vast majority of these were Ia. The remaining 7 % represented a previously unreported haplotype. DNA sequencing of this new haplotype also confirmed a single base nucleotide substitution that resulted in loss of EcoRI restriction site and gain of two additional MspI sites in cox1 and atp1 genes, respectively. There were 28 polymorphic sites among all nucleotide sequences including five reference isolates. Sites with alignment gaps were observed in P4 with one nucleotide deletion in 11 Ethiopian isolates. None of the reference sequence produced frame-shifts, with the exception of the 3-nucleotide deletion in the P4 region by Phytophthora andina, a feature that can be used to distinguish the new Ethiopian isolates from P. andina. While a distinguishing molecular data presented here clearly separated them from P. infestans, 7 % of the isolates that share this feature formed an important component of the late blight pathogen causing disease on Solanum tuberosum in Ethiopia. Thus, these Ethiopian isolates could represent a novel Phytophthora species reported for the first time here.

Two separate field experiments were conducted on hot pepper in which the genetic, heritability and environmental components of variation for seven plant and fruit traits in 78 genotypes and gene effects for four fruit traits in six generations of five crosses were estimated. The objectives were to determine the variation and effects of genes controlling inheritance of plant and fruit traits, and to propose efficient breeding procedures for improving the crop. Analysis of variance in half-diallel crosses revealed the presence of total genetic variability for seven traits among the 78 experimental entries with an excess of over-dominance genes. The presence of unequal distributions of dominant genes with positive and negative effects was observed among the parents and indicated the need to be cautious while selecting hot pepper parents for breeding purposes. Significant variability was also revealed in environmental sensitivity among the 78 experimental entries for some traits along with high heritability, which could be an advantage for a plant breeder but provides less clear opportunities for an agronomist to achieve better plant and fruit traits. Progeny generations (F(1), F(2), B(1) and B(2)) were found to perform better for fruit traits than their parents (P(1) and P(2)). The presence of significant gene interactions indicated a polygenic inheritance of the fruit traits studied and the possibility of pyramiding favorable alleles in the required directions at different levels of progeny generations. Heterosis, backcrossing, multiple crossing and pedigree breeding methods with recurrent selection may facilitate simultaneous exploitation of the genetic components and gene effects obtained. Nevertheless, it is doubtful whether selection efforts within the current set of hot pepper parents would be beneficial to achieve superior fruit traits for developing new varieties.