| 51. |
- Mukamuhirwa, Alphonsine, et al.
(författare)
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Effect of intermittent drought on grain yield and quality of rice (Oryza sativa L.) grown in Rwanda
- 2020
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Ingår i: Journal of Agronomy and Crop Science. - : Wiley. - 0931-2250 .- 1439-037X. ; 206, s. 252-262
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Tidskriftsartikel (refereegranskat)abstract
- The climate change will contribute drought and temperature extremes to rice growing systems, especially when cultivated in equatorial regions. To evaluate opportunities to cultivate and breed drought-tolerant rice, seven rice cultivars were evaluated in Rwanda for recurring morphological drought scores, grain yield and components, and quality characteristics. The cultivation conditions, that is site and drought treatment, impacted morphological drought scores, growth and yield attributes, while cultivar affected quality attributes. Thus, site showed a higher impact on grain yield and components than drought and cultivar, with generally a reduced grain yield at the low-temperature site, as a result of low spikelet fertility. Morphological drought scores were generally increased by drought, while drought at the reproductive stage at the high-temperature site was negative for yield and its components. The cultivars "Intsindagirabigega" and "Jyambere" were adapted to high-temperature site conditions. The cultivar "Intsindagirabigega" had the highest amylose content, and "Mpembuke," the highest antioxidant capacity. Thus, climate change with increased temperature and drought extremes may increase rice productivity in cool areas, while especially drought at reproductive stage will be detrimental in low altitude areas with high temperature. Cultivar variation indicated opportunities for selection and breeding of climate change tolerant rice cultivars which should be of immediate priority.
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| 52. |
- Mukamuhirwa, Alphonsine, et al.
(författare)
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Quality and Grain Yield Attributes of Rwandan Rice (Oryza sativa L.) Cultivars Grown in a Biotron Applying Two NPK Levels
- 2018
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Ingår i: Journal of Food Quality. - : Hindawi Limited. - 0146-9428 .- 1745-4557. ; 2018
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Tidskriftsartikel (refereegranskat)abstract
- High-yielding rice cultivars with good processing quality and rich in nutrition suitable to a changing climate are of particular importance for future rice-based food production. Here, seven Rwandan rice cultivars were grown in a climate chamber of the biotron facility at the Swedish University of Agricultural Sciences, to be evaluated for their grain yield, nutritional composition, and dough mixing properties. Two different levels of inorganic fertilizer were applied weekly from the seedling stage until flowering. Significant differences for grain yield and quality attributes were found between cultivars. Jyambere showed significantly the highest yield while Ingwizabukungu, Nemeyubutaka, and Jyambere were high in mineral elements content. Ndamirabahinzi and Mpembuke had the highest levels of TPC and TAC. Generally, the lower fertilizer dose resulted in a better performance of the cultivars for both yield and quality attributes. Significantly higher content of Fe, Ca, and Ba was found in grains from the moderate fertilizer dose, whereas K, Na, P, S, Zn, Cd, and Pb increased in grains from the higher fertilizer dose. The cultivar Ndamirabahinzi showed less variability of evaluated characters across fertilizer doses. The results from this study may be used for rice breeding of cultivars with high yield and good grain quality.
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| 53. |
- Mulugeta, Behailu, et al.
(författare)
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Genetic Diversity of Durum Wheat (Triticum turgidum L. ssp. durum, Desf) Germplasm as Revealed by Morphological and SSR Markers
- 2023
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Ingår i: Genes. - 2073-4425. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Ethiopia is considered a center of origin and diversity for durum wheat and is endowed with many diverse landraces. This research aimed to estimate the extent and pattern of genetic diversity in Ethiopian durum wheat germplasm. Thus, 104 durum wheat genotypes representing thirteen populations, three regions, and four altitudinal classes were investigated for their genetic diversity, using 10 grain quality- and grain yield-related phenotypic traits and 14 simple sequence repeat (SSR) makers. The analysis of the phenotypic traits revealed a high mean Shannon diversity index (H′ = 0.78) among the genotypes and indicated a high level of phenotypic variation. The principal component analysis (PCA) classified the genotypes into three groups. The SSR markers showed a high mean value of polymorphic information content (PIC = 0.50) and gene diversity (h = 0.56), and a moderate number of alleles per locus (Na = 4). Analysis of molecular variance (AMOVA) revealed a high level of variation within populations, regions, and altitudinal classes, accounting for 88%, 97%, and 97% of the total variation, respectively. Pairwise genetic differentiation and Nei’s genetic distance analyses identified that the cultivars are distinct from the landrace populations. The distance-based (Discriminant Analysis of Principal Component (DAPC) and Minimum Spanning Network (MSN)) and model-based population stratification (STRUCTURE) methods of clustering grouped the genotypes into two clusters. Both the phenotypic data-based PCA and the molecular data-based DAPC and MSN analyses defined distinct groupings of cultivars and landraces. The phenotypic and molecular diversity analyses highlighted the high genetic variation in the Ethiopian durum wheat gene pool. The investigated SSRs showed significant associations with one or more target phenotypic traits. The markers identify landraces with high grain yield and quality traits. This study highlights the usefulness of Ethiopian landraces for cultivar development, contributing to food security in the region and beyond.
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| 54. |
- Mulugeta, Behailu, et al.
(författare)
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Harnessing genome-wide genetic diversity, population structure and linkage disequilibrium in Ethiopian durum wheat gene pool
- 2023
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Ingår i: Frontiers in Plant Science. - 1664-462X.
-
Tidskriftsartikel (refereegranskat)abstract
- Yanyang Liu, Henan Academy of Agricultural Sciences (HNAAS), China; Landraces are an important genetic source for transferring valuable novel genes and alleles required to enhance genetic variation. Therefore, information on the gene pool’s genetic diversity and population structure is essential for the conservation and sustainable use of durum wheat genetic resources. Hence, the aim of this study was to assess genetic diversity, population structure, and linkage disequilibrium, as well as to identify regions with selection signature. Five hundred (500) individuals representing 46 landraces, along with 28 cultivars were evaluated using the Illumina Infinium 25K wheat SNP array, resulting in 8,178 SNPs for further analysis. Gene diversity (GD) and the polymorphic information content (PIC) ranged from 0.13–0.50 and 0.12–0.38, with mean GD and PIC values of 0.34 and 0.27, respectively. Linkage disequilibrium (LD) revealed 353,600 pairs of significant SNPs at a cut-off (r2 > 0.20, P < 0.01), with an average r2 of 0.21 for marker pairs. The nucleotide diversity (π) and Tajima’s D (TD) per chromosome for the populations ranged from 0.29–0.36 and 3.46–5.06, respectively, with genome level, mean π values of 0.33 and TD values of 4.43. Genomic scan using the Fst outlier test revealed 85 loci under selection signatures, with 65 loci under balancing selection and 17 under directional selection. Putative candidate genes co-localized with regions exhibiting strong selection signatures were associated with grain yield, plant height, host plant resistance to pathogens, heading date, grain quality, and phenolic content. The Bayesian Model (STRUCTURE) and distance-based (principal coordinate analysis, PCoA, and unweighted pair group method with arithmetic mean, UPGMA) methods grouped the genotypes into five subpopulations, where landraces from geographically non-adjoining environments were clustered in the same cluster. This research provides further insights into population structure and genetic relationships in a diverse set of durum wheat germplasm, which could be further used in wheat breeding programs to address production challenges sustainably.
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| 55. |
- Mulugeta, Behailu, et al.
(författare)
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Marker-trait association analyses revealed major novel QTLs for grain yield and related traits in durum wheat
- 2023
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- The growing global demand for wheat for food is rising due to the influence of population growth and climate change. The dissection of complex traits by employing a genome-wide association study (GWAS) allows the identification of DNA markers associated with complex traits to improve the productivity of crops. We used GWAS with 10,045 single nucleotide polymorphism (SNP) markers to search for genomic regions associated with grain yield and related traits based on diverse panels of Ethiopian durum wheat. In Ethiopia, multi-environment trials of the genotypes were carried out at five locations. The genotyping was conducted using the 25k Illumina Wheat SNP array to explore population structure, linkage disequilibrium (LD), and marker-trait associations (MTAs). For GWAS, the multi-locus Fixed and Random Model Circulating Probability Unification (FarmCPU) model was applied. Broad-sense heritability estimates were high, ranging from 0.63 (for grain yield) to 0.97 (for thousand-kernel weight). The population structure based on principal component analysis, and model-based cluster analysis revealed two genetically distinct clusters with limited admixtures. The LD among SNPs declined within the range of 2.02-10.04 Mbp with an average of 4.28 Mbp. The GWAS scan based on the mean performance of the genotypes across the environments identified 44 significant MTAs across the chromosomes. Twenty-six of these MTAs are novel, whereas the remaining 18 were previously reported and confirmed in this study. We also identified candidate genes for the novel loci potentially regulating the traits. Hence, this study highlights the significance of the Ethiopian durum wheat gene pool for improving durum wheat globally. Furthermore, a breeding strategy focusing on accumulating favorable alleles at these loci could improve durum wheat production in the East African highlands and elsewhere.
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| 56. |
- Mulugeta, Behailu, et al.
(författare)
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Multivariate analyses of Ethiopian durum wheat revealed stable and high yielding genotypes
- 2022
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Improving crop adaptation and stability across diverse and changing environmental conditions is essential to increasing grain yield per unit area. In turn, this contributes to meeting the increasing global food demand. Nevertheless, a number of factors challenge the efficiency of crop improvement programs, of which genotype-by-environment interaction (GEI) is one of the major factors. This study aimed to evaluate the performance and phenotypic stability of 385 Ethiopian durum wheat landraces and 35 cultivars; assess the pattern of genotype by environment interaction (GEI) effect, and identify stable and high-yielding landraces or cultivars using the additive main effect and multiplicative interaction (AMMI) and genotype main effect plus genotype by environment interaction biplot (GGE-biplot). The experiment was laid out in an alpha lattice design with two replications at five test sites (Akaki, Chefe Donsa, Holeta, Kulumsa, and Sinana). The combined analysis of variance revealed highly significant effects (P ≤ 0.01) of environments (E), genotype (G), and GEI on a phenotypic variation of traits evaluated, including grain yield. For all traits, the amount of phenotypic variance and GEI explained by the GGE biplot was higher than in AMMI2, but both exhibited significant effects of E and GEI on the genotypes. The AMMI model identified G169, G420, G413, G139, G415, G416, G417, and G418 as stable genotypes across testing sites. Whereas, the GGE biplot identified G169, G420, G415, G139, G106, G412, G413, and G417 as both high-yielding and stable across test sites. Hence, genotypes identified as stable and high yielding in the present study could be used in a durum wheat breeding program aimed at identifying genes and molecular markers associated with the crop’s productivity traits as well as developing stable and high-yielding cultivars for use in East Africa and beyond.
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| 57. |
- Mulugeta, Behailu, et al.
(författare)
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Unlocking the genetic potential of Ethiopian durum wheat landraces with high protein quality: Sources to be used in future breeding for pasta production
- 2024
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Ingår i: Food and energy security. - 2048-3694. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- The content and composition of the grain storage proteins in wheat determine to a high extent its end-use quality for pasta and bread production. This study aimed to evaluate the content and composition of the grain storage proteins in Ethiopian landraces and cultivars to contribute to future breeding toward improved pasta quality. Thus, 116 landraces and 34 cultivars originating from Ethiopia were grown in three locations, and the protein parameters were analyzed using size exclusion-high performance liquid chromatography (SE-HPLC). A considerable variation in the amount of the analyzed protein parameters was found. The genotypes, environments, and interactions contributed significantly (p < 0.001) to the differences obtained. The broad-sense heritability was high (0.75-0.98) for all protein parameters except for unextractable small monomeric protein (uSMP). Using the principal component analysis (PCA) to evaluate the impact of protein parameters and using either PCA or unweighted pair group method with arithmetic mean (UPGMA) to assess the impact of the genetic composition, the cultivar group was found to form a separate cluster. This indicates that durum wheat improvement in Ethiopia has relied on exotic materials, which might result from a narrow genetic base. Unlike most landraces, most released cultivars showed a high and stable gluten strength across environments. Two landraces, G057 and G107, were found genetically distinct from the released cultivars but with high and stable gluten. The two selected landraces might be of extremely high value for future use in durum wheat breeding programs, as they might be adapted to wide-ranging Ethiopian growing conditions, they might carry genes of relevance to withstand abiotic and biotic stresses, and they seem to hold essential protein properties, which might result in high-quality grains for industrial processes.
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| 58. |
- Muzila, Mbaki, et al.
(författare)
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Assessment of diversity in Harpagophytum with RAPD and ISSR markers provides evidence of introgression
- 2014
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 151, s. 91-101
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Tidskriftsartikel (refereegranskat)abstract
- The genus Harpagophytumhas two species: H. procumben swhich is an important medicinal plant in southern Africa, and H. zeyheri. Genetic diversity in 96 samples, obtained by germinating seeds collected from Botswana, was assessed using six inter-simple sequence repeat (ISSR) and 10 random amplified polymorphic DNA (RAPD) primers. These DNA markers yielded a total of 138 polymorphic bands. Polymorphism information content (PIC) ranged from 0.06 to 0.39 for ISSR primers, and from 0.09 to 0.43 for RAPD primers. Jaccard's similarity coefficients were highest when seedlings derived from the same fruit capsule were compared, while seedlings from different fruits on the same plant had intermediate values. The lowest values were recorded among seedlings from different plants. These results were consistent with an outcrossing breeding system in Harpagophytum. Analysis of molecular variance revealed significant differentiation (P < 0.01) between taxonomic units within Harpagophytum. About 39% of the variability occurred between the two species, H. procumbens and H. zeyheri. Plants with an intermediate morphology, i.e. putative hybrids (PH), showed 21% differentiation when compared with H. procumbens ssp. procumbens (PP), and 19% when compared with H. procumbens ssp. transvaalense (PT) or with H. zeyheri (ZZ). In addition, a deviating variant of PT was identified, here termed ‘procumbens new variety’ (PN). PN showed only 9% differentiation when compared with PT, 22% when compared with PP or with PH, and 41% when compared with ZZ. Considerable differentiation between the two Harpagophytum species was revealed also by a cluster analysis. Introgression was, however, suggested by the intermediate position of the putative hybrid plants in a principal component analysis while inter-specific gene flow was shown by a Bayesian genetic structure analysis.
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| 59. |
- Odilbekov, Firuz, et al.
(författare)
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QTL Mapping for resistance to early blight in a tetraploid potato population
- 2020
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Ingår i: Agronomy. - : MDPI AG. - 2073-4395. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Early blight of potato, caused by Alternaria solani, is an economically important foliar disease in most potato-growing regions. Growing cultivars with higher levels of resistance to early blight can reduce tuber yield losses and the need for fungicide applications. In this research, a bi-parental tetraploid potato population, segregating for resistance to early blight in leaves and tubers, was characterized to identify novel quantitative trait loci (QTL) associated with foliar and tuber early blight resistance. Assessment of the disease resistance in the foliage was performed by field evaluation and in tuber under controlled conditions. Results from this study revealed significant differences (P < 0.001) in resistance to A. solani among potato clones both in the leaves and in tubers. There was no statistically significant correlation (r = 0.06, P = 0.35) between the resistance scores from leaves and tubers. Several clones exhibited; however, high levels of resistance both in leaves and tubers and are; thus, promising candidates for breeding for early blight resistance. Linkage mapping revealed several QTL for early blight affecting both foliage and tubers. QTL associated with disease resistance in the tuber were found on chromosomes 1, 2, 3, 4, 8, 11 and 12. QTL associated with disease resistance in foliage were also examined for independence from defoliation, and independent QTL were; thus, found on chromosomes 5 and 11.
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| 60. |
- Ortiz Rios, Rodomiro Octavio, et al.
(författare)
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Adaptability, stability, and productivity of potato breeding clones and cultivars at high latitudes in Europe
- 2024
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Ingår i: Discover life. - 2948-2968 .- 2948-2976. ; 54
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Tidskriftsartikel (refereegranskat)abstract
- The aim of potato breeding is to release cultivars that exhibit high and stable performance across the target population of environments. The objective of this research was therefore to investigate the use of various methods (site regression [SREG], coefficient of variation and regression deviation [σ2δ]) for determining the adaptability and stability of productive and quality traits in the Nordic region of Europe. The multi-environment trials included 256 breeding clones and released cultivars grown by EU farmers at three distinct testing sites over two years in Sweden. There was significant (P < 0.001) variation in tuber yield, starch percentage and reducing sugars in the tuber flesh among the breeding clones and cultivars, testing environments and the genotype by environment interaction (GEI). The environments were very diverse, as revealed by the SREG biplots and particularly for the GEI patterns noted in terms of their productive and quality characteristics. The percentage of stable high-tuber yielding germplasm was greater for breeding clones (23%) than for released European cultivars (2%), thus revealing the advantage of potato breeding in the target population of environments. SLU 1415001 and SLU 1314015 were the most promising breeding clones due to their stable high tuber yield. This characteristic was best for the starch potato cultivars, although none of them exhibited a significant different σ2δ. ‘Talent’ shows an almost stable good performance among low reducing sugar cultivars and breeding clones, which are often unstable in terms of their scoring across environments. Neither a breeding clone nor a cultivar was at the top for stable tuber yield, tuber flesh starch or reducing sugars in the tuber flesh, which shows the challenge faced by potato breeding while addressing the needs of different markets.
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