International Institute Of Tropical Agriculture Research Articles

The parasitic fly Nemorilla maculosa exploits host‐plant volatiles to locate the legume pod borer, Maruca vitrata

AbstractNemorilla maculosa Meigen (Diptera: Tachinidae) is a solitary endoparasitoid of the legume pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae), a key pest of cowpea, Vigna unguiculata (L.) Walp. (Fabaceae) in Africa. A colony of N. maculosa, introduced for experimental purposes from Taiwan to the laboratories of the International Institute of Tropical Agriculture (IITA) in Benin, was used for our studies. Olfactory reponses of N. maculosa to leaves of infested or uninfested cowpea and yellow peabush, Sesbania cannabina (Retz.) Pers. (Fabaceae), and to M. vitrata larvae were evaluated in a four‐arm olfactometer. For all combinations of odor sources, responses between naïve and oviposition‐experienced female flies did not differ. Nemorilla maculosa females were attracted by odors from uninfested leaves of yellow peabush and flowers of cowpea when compared with clean air, and they were attracted to plants damaged by M. vitrata with larvae removed. However, the female fly did not discriminate between odors from infested and uninfested plants. The parasitic fly N. maculosa proved well able to use volatile compounds from various host plants (peabush and cowpea) to locate its host, with a more pronounced attraction by the combination of host larvae and infested host plant parts. These findings are discussed in light of the prospective use of N. maculosa as a biological control agent against the legume pod borer.

Estimating Global Solar Radiation from Routine Meteorological Parameters Over a Tropical City (7.23°N; 3.52°E) Using Quadratic Models

Abstract The need for adequate solar radiation is ever increasing for various applications. However there is an inadequate data of solar radiation in many countries due to the cost of instrument set up. Hence this study investigates two models for estimating solar radiation from routinely measured meteorological parameters. The data were obtained from the International Institute of Tropical Agriculture, Ibadan. The regression coefficients of the quadratic models were determined and used to estimate the global solar radiation for both forward and backward predictions. Their predictive accuracies were compared with four other models and the measured values using standard statistical error indicators. The results showed for forward as compared to backward predictions in bracket root mean square errors 1.2 (1.1); mean bias errors 1.1 (0.8) and mean percentage errors -4.8% (-2.9%) while for backward prediction 1.9 (1.7), 1.7 (1.4) and 7.9% (2.2%) measured in KJm−2day−1 respectively. A positive error value shows an over estimation while a negative value shows an under estimation. The models are versatile for estimating global solar radiation at the horizontal surface, fixing missing data and correcting outliers.

Investigation of the Breeding Mechanism of African Yam Bean [Fabaceae] (Sphenostylis stenocarpa Hochst. Ex. A. Rich) Harms

The many reported inherent nutritional potential in African yam bean (Sphenostylis stenocarpa (Hochst. Ex. A. Rich.) Harms) seem to provide platform for the need of its genetic improvement. A good understanding of the breeding system of the crop species is a needed criterion in plant breeding program. Four accessions of African yam bean (AYB) collected from the Genetic Resources Centre of the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria were grown out in a fifteen plants/accession row on a field at IITA, Ibadan (7.5°N, 3.9°E), Nigeria. Five pollination mechanisms were investigated as treatments on the four accessions. The four accessions set fruits and seeds in four treatments: plants left to open-pollination (A), plants isolated with fine net mesh (B), artificially selfed flowers (C) and inter-varietal cross-pollination (D). Emasculated flowers which were not pollinated (treatment E) produced neither fruit nor seed. Treatment A differed significantly (P<0.05) from B, likewise C and D. Fruit set percentage was higher in A (19.7-21.2) than B (18.3–18.7). Higher pollination/fertilization success (46.5%) was obtained in C compared to 32.3% in D. More seeds (88.6%) were set by self-pollination. The four accessions had a mean selfing rate of 89.8% and an outcrossing rate of 10.17%. The observed 1:9 allogamy: autogamy in this study could form the basis for developing the breeding strategy for the genetic improvement of AYB via hybridization.

Physiological and Agronomic Responses of Four Rice Varieties to Drought in the Rainforest

The present investigation tested the hypothesis that there would be variation in physiological responses to water deficit among rice varieties from different production ecologies, with contrasting tolerance to water deficit under repeated cycle of soil moisture deficit, at reproductive growth stage. A screen house and a field trial were conducted at International Institute of Tropical Agriculture, Ibadan and Ikenne (Latitude 6° 52' N, Longitude 3° 43' E) respectively. Both experiments had rice varieties (‘IR 64’, ‘WAB 56-104’, ‘IR 77298-1-2-B-10’ and ‘NERICA 4’) and stress status (stress and control) as treatment factor’s, arranged in a randomised complete block design with three replicates. In both trials, the physiological mechanism that underpins varietal differences with repeated cycles of water deficit at the reproductive growth stage was more balanced water status, improved foliar characters, efficient photosynthetic capacity and higher grain yield in comparatively drought tolerant upland rice varieties (‘NERICA 4’ and ‘WAB 56-104’), as opposed with the results for the drought susceptible cultivar ‘IR 64’. A converse pattern was observed on water stressed rice, despite fewer cycles of water deficit on the field. The results could have suggested that the initiation of water deficit is the rate limiting step rather than its intensity at the reproductive growth stage.

Mycological evaluation of the phylloplane of <i>Vigna unguiculata</i> (L.) Walp

Cowpea a leguminous crop consumed by millions of people in Asia and sub-Sahara Africa often faces pre- and postharvest attack like fungal infection. Twelve cultivars of Vigna unguiculata (L.) Walp obtained from International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria were investigated for fungal infection using pour plate technique and eleven fungal isolates were obtained from nine of the cultivars. Pathogenicity of Fusarium oxysporium (cultivars IT8ID-994, IT98K-452-1); Alternaria alternata (cultivars IT98k-205-8, TVX3236, IT845-2246- 4); Colletotrichum truncatum (cultivars IT86D-719, Ife brown, (IA4B45)244, IT90k-277-2) and Sclerotium rolfsii (cultivars Ife brown, (IA4B45)244, IT845-2246-4) was confirmed on these nine cultivars of cowpea showing varying percentage of disease occurrence. The incessant attack on cowpea plant both on the field and in storage calls for more research in the area of disease resistant varieties for the ever growing population. Keywords: Vigna unguiculata , phylloplane, pathogenicity, fungal infection

English

Cassava is the main crop in the Congo but its low yield doesn’t meet the needs of Congolese populations. The low yield is due to the use of less effective sensitive varieties to diseases, non-mastering of techniques and biotic constraint of which the African cassava mosaic. This study aims at selecting resistant genotypes to the African cassava mosaic and assessing their agronomic and production performances. Six elite accessions selected based on a villager participative approach have been crossed by controlled pollination with three clones (192/0401, 192/0325 and 197/0162) distributed by the International Institute for Tropical Agriculture (IITA). Growth, agronomic and production parameters of genotypes from the controlled pollination were evaluated at the station. Of the ten tested genotypes, the one resulting from the crossing (Mahabama x I92/0401) did not show any symptom of the cassava mosaic disease 12 months after planting. Apart from the root length, foliar surface and the height of the plant, this genotype differed from the others only by the biomass, the diameter of the stem, the harvest index, the rate of starch, the rate of dry matter and marketable or non-marketable tuberous roots. The genotype (Mahabama x I92/0401) will be included in the cassava improvement section plan in the Republic of Congo. Key words: Cassava, Congo, African.

Profitability Analysis of Non-timber Forest Products Collected from Block A and Golf Course Forests of International Institute of Tropical Agriculture (IITA), Ibadan, Oyo State, Nigeria

Profitability Analysis of Non-timber Forest Products Collected from Block A and Golf Course Forests of International Institute of Tropical Agriculture (IITA), Ibadan, Oyo State, Nigeria

Exchanging and managing in-vitro elite germplasm to combat Cassava Brown Streak Disease (CBSD) and Cassava Mosaic Disease (CMD) in Eastern and Southern Africa

Cassava varieties resistant to cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) are needed for the food and income security of the rural poor in eastern and southern Africa (ESA). The International Institute of Tropical Agriculture led five national cassava breeding programs (Malawi, Mozambique, Kenya, Tanzania and Uganda) in virus-cleaning and exchanging elite cassava germplasm resistant to both diseases. This paper documents the experiences and lessons learned from the process. Thirty-one clones (25 elite, two standard and four national) were submitted by the five breeding programs to the Natural Resources Institute and Kenya Plant Health Inspectorate Services for virus cleaning and indexing. Subsequently, ca 75 in-vitro virus-indexed plantlets per clone were sent to Genetic Technologies International Limited (GTIL), a private tissue culture (TC) lab in Kenya, and micro-propagated to produce ≥1500 plantlets. After fulfilling all the formal procedures of germplasm exchange between countries ≥300 plantlets per clone were sent to each partner country. National check clones susceptible to CMD/CBSD were sent only to their countries of origin. In each country, the in-vitro plantlets were acclimatized under screen house conditions and transferred to clean isolated sites for field multiplication. All the clones were cleaned of the viruses, except Tomo. The cleaning process was slow for F19-NL, NASE1, and Kibandameno and TC micro-propagation at GTIL was less efficient for Pwani, Tajirika, NASE1, and Okhumelela than for the other clones. Difficulties in cleaning recalcitrant clones affected the timeline for establishing the multi-site evaluation trials in target countries. The initiative is the one of the kind to successfully clean and exchange elite germplasm as a joint action to combat CBSD in ESA. Adequate preparation in terms of infrastructure and personnel are critical to successfully receiving and adapting the indexed in-vitro plants as new germplasm.

Determinants of the Quantity of Non-timber Forest Products Collected from Forests of the International Institute of Tropical Agriculture in Ibadan, Nigeria

Determinants of the Quantity of Non-timber Forest Products Collected from Forests of the International Institute of Tropical Agriculture in Ibadan, Nigeria

Aluminium tolerance: a determinant factor to cowpea Vigna unguiculata (L.) Walp. (Fabales: Fabaceae) productivity

Alternative approach to mitigate the negative consequences of aluminium toxicity on cowpea Vigna unguiculata (L.) Walp. (Fabales: Fabaceae) productivity cannot be overemphasized. The effects of aluminium toxicity on some morphological parameters of five cowpea accessions were investigated with the aim of determining the threshold of tolerance for the crop. Five cowpea accessions were collected from the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. The seedlings were raised in perforated plastic pots filled with 10 kg of top soil and treated till maturity with 50 µm, 100 µm, 200 µm of AlCl3 while those irrigated with tap water served as the control (0 µm). Variations were observed among accessions and treatments as plant height was accession dependent in contrast to stem girth, number of branches, root growth and shoot growth. Suppression of root growth among the accessions were attributed to more carbon allocation to the shoot at the expense of shoot growth leading to chlorosis, necrosis and reduced photosynthetic capacity among the accessions. Accession 5 was adjudged the best among the accessions based on the response to aluminium treatment. However, further research on the mechanism of tolerance especially at the molecular level is highly recommended.

Effect of Drying Temperature on the Chemical Qualities of Breadfruit

Drying is described as the reduction of material moisture to the required dryness values as a definite process and it is of major interest in food processing. This study aimed at studying the influence of drying temperature on the functional and pasting properties of breadfruit flour using cabinet dryer with a view of establishing potential industrial utilization of breadfruit flour as food and food ingredients. Freshly harvested breadfruits (matured) (Artocarpus atilis) were obtained from International Institute for Tropical Agriculture (IITA), Ibadan, Oyo State, Nigeria. They were washed in clean water to remove adhering latex and dirt and were peeled, rewashed, drained and sliced manually to 3mm thickness for uniformity in drying, and then dried with a cabinet dryer at 50, 60 and 70°C respectively until constant weights were achieved, after which they were milled into flour. The flour samples were screened through a 0.20mm British standard sieve. Pasting and functional properties were determined using standard methods. The variations in the functional and pasting properties were significant at p<0.05 for temperature of 50, 60 and 70°C respectively. The functional properties of the breadfruit flour ranged from 279.17% - 374.73% for oil absorption capacity, 0.34% - 0.46% for bulk density, 93.63% - 94.70% for dispersibility, 200%–800% for foaming capacity, 2% for gelation, 390.32% - 467.04% for water absorption capacity, 137.07% - 230.67% for swelling capacity at 55°C, 217.29% -333.32% for swelling capacity at 65°C, 142.73% - 323.60% for swelling capacity at 75°C, and 4.58% - 6.27% for solubility at 55°C, 3.24% - 6.40% for solubility at 65°C, 1.97% - 6.66% for solubility at 75°C. The pasting properties for the breadfruit flour ranged from 2309.00RVU - 3142.50RVU, 2145.5RVU-2955.5RVU, 159.5VU - 187.5RVU, 4879.00RVU - 7192.50RVU, 2729.50RVU -4237.00RVU, 6.10 - 6.27 and 50.40°C–53.98°C for peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity, peak time and pasting temperature. Respectively. There was an increase in functional and pasting properties as the temperature increases. This result showed that the breadfruit flour can be used as food ingredients.

Improving Genomic Prediction in Cassava Field Experiments Using Spatial Analysis.

Cassava (Manihot esculenta Crantz) is an important staple food in sub-Saharan Africa. Breeding experiments were conducted at the International Institute of Tropical Agriculture in cassava to select elite parents. Taking into account the heterogeneity in the field while evaluating these trials can increase the accuracy in estimation of breeding values. We used an exploratory approach using the parametric spatial kernels Power, Spherical, and Gaussian to determine the best kernel for a given scenario. The spatial kernel was fit simultaneously with a genomic kernel in a genomic selection model. Predictability of these models was tested through a 10-fold cross-validation method repeated five times. The best model was chosen as the one with the lowest prediction root mean squared error compared to that of the base model having no spatial kernel. Results from our real and simulated data studies indicated that predictability can be increased by accounting for spatial variation irrespective of the heritability of the trait. In real data scenarios we observed that the accuracy can be increased by a median value of 3.4%. Through simulations, we showed that a 21% increase in accuracy can be achieved. We also found that Range (row) directional spatial kernels, mostly Gaussian, explained the spatial variance in 71% of the scenarios when spatial correlation was significant.

Genetic Variability, Correlation and Path Coefficient Analysis in Seed Yield and Related Traits of Cowpea (Vigna Unguiculata (L.)Walp) Germplasm Accessions on High Altitude Area of Jos Plateau

A field experiment was carried out at Dagwom farm at National Veterinary Research Institute (NVRI) Vom, in Jos South Local Government area of Plateau state Nigeria (Lat.09044N, long.08047E, altitude 1293.2 m above sea level) in 2013 and 2014 rainy seasons, to evaluate the genetic variability, correlation and path coefficient analysis in seed yield and related traits of cowpea. The treatments consisted of eighty (80) cowpea germplasm accessions obtained from International Institute for Tropical Agriculture (IITA) Ibadan Nigeria. The experiment was laid out in a Randomized Complete Block Design (RCBD) in two replicates. The Analysis of Variance (ANOVA) showed significant difference at (P<0.01) among the entries for all the yield and related traits accessed. High phenotypic coefficient of variability (PCV) compared with genotypic coefficient of variability (GCV) coupled with low Environmental coefficient of variability (ECV) was observed for all the yield and related traits accessed. High broad sense heritability (H2B) and genetic advance (GAM (%) was observed for the entire yield and related traits accessed except days to maturity which recorded high heritability with moderate genetic advance. Significant positive correlation was observed between grain yield and number of pod per plant (r=0.572**), hundred seed weight (r=0.504**), pod length (r=0.523**), number of secondary branches per plant (r=0.450**), number of seed per pod (r=0.431**), number of primary branches per plant (r=0.339**) plant height (r=0.285*), suggests that improving any of these characters will boost grain yield of cowpea. Path coefficient analysis showed that, number of pod per plant (P=0.65), hundred seed weight (P=0.54), number of seed per pod ((P=0.29) number of secondary branches per plant ((P=0.16), plant height (P=0.05)), and pod length ((P=0.04) contributed directly to grain yield. The result from this study therefore revealed that hundred seed weight, number of pod per plant, number of secondary branches per plant, number of seed per pod, pod length and plant height recorded high genetic variability, heritability and genetic advance coupled with high significant genotypic correlation with grain yield and contributed directly to grain yield. Therefore, these characters should be considered when planning hybridization programme for cowpea yield improvement.

Looking back and moving forward: 50 years of soil and soil fertility management research in sub-Saharan Africa

ABSTRACTLow and declining soil fertility has been recognized for a long time as a major impediment to intensifying agriculture in sub-Saharan Africa (SSA). Consequently, from the inception of international agricultural research, centres operating in SSA have had a research programme focusing on soil and soil fertility management, including the International Institute of Tropical Agriculture (IITA). The scope, content, and approaches of soil and soil fertility management research have changed over the past decades in response to lessons learnt and internal and external drivers and this paper uses IITA as a case study to document and analyse the consequences of strategic decisions taken on technology development, validation, and ultimately uptake by smallholder farmers in SSA. After an initial section describing the external environment within which soil and soil fertility management research is operating, various dimensions of this research area are covered: (i) ‘strategic research’, ‘Research for Development’, partnerships, and balancing acts, (ii) changing role of characterization due to the expansion in geographical scope and shift from soils to farms and livelihoods, (iii) technology development: changes in vision, content, and scale of intervention, (iv) technology validation and delivery to farming communities, and (v) impact and feedback to the technology development and validation process. Each of the above sections follows a chronological approach, covering the last five decades (from the late 1960s till today). The paper ends with a number of lessons learnt which could be considered for future initiatives aiming at developing and delivering improved soil and soil fertility management practices to smallholder farming communities in SSA.

Genetic variation and population structure of maize inbred lines adapted to the mid-altitude sub-humid maize agro-ecology of Ethiopia using single nucleotide polymorphic (SNP) markers

BackgroundMolecular characterization is important for efficient utilization of germplasm and development of improved varieties. In the present study, we investigated the genetic purity, relatedness and population structure of 265 maize inbred lines from the Ethiopian Institute of Agricultural Research (EIAR), the International Maize and Wheat Improvement Centre (CIMMYT) and the International Institute of Tropical Agriculture (IITA) using 220,878 single nucleotide polymorphic (SNP) markers obtained using genotyping by sequencing (GBS).ResultsOnly 22% of the inbred lines were considered pure with <5% heterogeneity, while the remaining 78% of the inbred lines had a heterogeneity ranging from 5.1 to 31.5%. Pairwise genetic distances among the 265 inbred lines varied from 0.011 to 0.345, with 89% of the pairs falling between 0.301 and 0.345. Only <1% of the pairs had a genetic distance lower than 0.200, which included 14 pairs of sister lines that were nearly identical. Relative kinship analysis showed that the kinship coefficients for 59% of the pairs of lines was close to zero, which agrees with the genetic distance estimates. Principal coordinate analysis, discriminant analysis of principal components (DAPC) and the model-based population structure analysis consistently suggested the presence of three groups, which generally agreed with pedigree information (genetic background). Although not distinct enough, the SNP markers showed some level of separation between the two CIMMYT heterotic groups A and B established based on pedigree and combining ability information.ConclusionsThe high level of heterogeneity detected in most of the inbred lines suggested the requirement for purification or further inbreeding except those deliberately maintained at early inbreeding level. The genetic distance and relative kinship analysis clearly indicated the uniqueness of most of the inbred lines in the maize germplasm available for breeders in the mid-altitude maize breeding program of Ethiopia. Results from the present study facilitate the maize breeding work in Ethiopia and germplasm exchange among breeding programs in Africa. We suggest the incorporation of high density molecular marker information in future heterotic group assignments.

Variability of host damage and response of some cowpea breeding lines to root-knot nematodes, &lt;i&gt;Meloidogyne&lt;/i&gt; spp.

Field and screen house studies were conducted at the International Institute of Tropical Agriculture (IITA) Research Farms, Minjibir, Kano State and farmer’s plot, Ringim, Jigawa State in Sudan Savannah Agro-ecological Zone, North-Western, Nigeria to investigate the reaction of ten cowpea breeding lines to infestation of Meloidogyne spp. Seven-day old seedlings were inoculated with 0 or 5000 eggs of Meloidogyne spp. The experiment was a 2 x 10 factorial, fitted into Randomized Complete Block Design laid out in the fields while the screen house trial laid in Completely Randomized Design. In each location, treatments were replicated four times. Data were collected on plant height, stem girth, root galls, number of days 50% to flowering, pods/plant and seeds/pod. Data obtained were subjected to Analysis of Variance. Statistically variable treatment means were separated using standard error of means at 5% level of probability. Results showed that Meloidogyne spp. induced stunting which results in poor growth and in severe cases affects the time of maturity on susceptible cowpea plants. Hence, highly nematode infested soil should be treated before sowing in order to ensure high qualitative harvest. Keywords: Cowpea, Meloidogyne spp., plant height, stem girth

Effect of Soaking and Boiling on Anti-nutritional Factors, Oligosaccharide Contents and Protein Digestibility of Newly Developed Bambara Groundnut Cultivars

Newly developed Bambara groundnut (Vigna subterranea L.) seeds (Accessions No: TVSU 5 – Bambara Groundnut White (BGW) and TVSU 146 – Bambara Groundnut Brown (BGB)) were collected from International Institute of Tropical Agriculture (IITA), Nigeria, planted and harvested. The effects of processing methods (soaking and boiling) on anti-nutritional factors and oligosaccharides content and protein digestibility of BGW and BGB compared with Bambara groundnut commercial (BGC) seeds were investigated. Soaking and boiling significantly reduced the anti-nutritional factors of the samples and the effect increased as processing time was elongated. Sample BGC had lower anti-nutritional factors than BGW and BGB after soaking for 48 h. Tannin contents of the samples were reduced drastically by 99 % throughout the soaking periods. Greatest loss in raffinose level was observed in BGB (59%) and BGW (50%) after boiling for 60 min compared with BGC (43%). The loss in stachyose content of the samples varies with processing and BGC (59%) had greatest loss after boiling for 60 min while soaking for 48 h reduced that of BGB and BGW by 57 and 35%, respectively. Boiling for 60 min increased the in vitro protein digestibility of BGB (89.34 %) compared with BGW (87.48%) and BGC (82.89%). Overall, the results demonstrated that soaking and boiling of newly developed Bambara groundnut seeds could improve the nutritive quality of the seeds.

Evaluation of Nutrient Parameters of Selected African Accessions of Bambara Groundnut (&lt;i&gt;Vigna &lt;/i&gt;&lt;i&gt;subterranea &lt;/i&gt;(L.) Verdc&lt;i&gt;.&lt;/i&gt;)

Developing countries, especially in Africa are facing challenges of malnourished conditions and food insecurity generally. Nutrients, being components of food ingredient required for survival, normal body function and satisfying the physiological and dietary requirements of the body metabolism [38]. Hence, for meaningful growth and developments in man, the type and amount of nutrients intake and its rate of absorption or level is crucial. However, much emphases and consumption pattern in Africa had been on common or routine food crops like rice, common beans, cassava, maize e.t.c., resulting in the reduced utilisation of other plant species, termed neglected and under-utilised species (NUS), like Bambara groundnut. Selected accessions of Bambara groundnut (Vigna subterranea (L.) Verdc), assembled at the International Institute of Tropical Agriculture, IITA, Ibadan, Nigeria were analysed for important nutrients parameters including moisture content, carbohydrate, protein, crude fibre, total sugar, fat, starch, ash and minerals, based on standard and established protocols at the Crop Utilisation laboratory, IITA, Ibadan, Nigeria. Moreso, samples were sent to the South African grain laboratory, the Willows, South Africa, for the determination of free and essential amino acids using HPLC and UPLC conditions. Results revealed that accessions TVSu – 1235, TVSu – 1231, TVSu – 1205, TVSu -729 and TVSu – 1824 could be regarded as high nutrients varieties, while TVSu – 1744, TVSu – 553 and TVSu - 922 are medium nutrients type, while the remaining accessions falls below the medium nutrient range, among these lines of Bambara groundnut evaluated. The protein values has a range of 15.88 ± 0.005 g / 100 g for TVSu – 1202 to 24.91 ± 0.011 g / 100 g for TVSu – 1231; while their carbohydrate content ranges from 42.77 ± 0.001 g / 100 g for TVSu – 1202 to 62.76 ± 0.223 g / 100 g for TVSu – 1744.

First Report of Maize yellow mosaic virus Infecting Sugarcane (Saccharum spp.) and Itch Grass (Rottboellia cochinchinensis) in Nigeria

HomePlant DiseaseVol. 101, No. 7First Report of Maize yellow mosaic virus Infecting Sugarcane (Saccharum spp.) and Itch Grass (Rottboellia cochinchinensis) in Nigeria PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Maize yellow mosaic virus Infecting Sugarcane (Saccharum spp.) and Itch Grass (Rottboellia cochinchinensis) in NigeriaA. Yahaya, M. Al Rwahnih, D. B. Dangora, L. Gregg, M. D. Alegbejo, P. Lava Kumar, and O. J. AlabiA. YahayaSearch for more papers by this author, M. Al RwahnihSearch for more papers by this author, D. B. DangoraSearch for more papers by this author, L. GreggSearch for more papers by this author, M. D. AlegbejoSearch for more papers by this author, P. Lava KumarSearch for more papers by this author, and O. J. AlabiSearch for more papers by this authorAffiliationsAuthors and Affiliations A. Yahaya , Department of Biological Sciences, Ahmadu Bello University, Zaria, Kaduna State, Nigeria M. Al Rwahnih , Department of Plant Pathology, University of California, Davis D. B. Dangora , Biological Sciences, Ahmadu Bello University, Zaria, Kaduna State, Nigeria L. Gregg , Texas A&M AgriLife Research and Extension Center, Weslaco, TX 78596 M. D. Alegbejo , Department of Crop Protection, Ahmadu Bello University, Zaria, Kaduna State, Nigeria P. Lava Kumar , International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, Nigeria O. J. Alabi , Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco, TX 78596. Published Online:9 May 2017https://doi.org/10.1094/PDIS-03-17-0315-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat During routine surveys conducted from February to July 2015 in the northern guinea savannah region of Nigeria, sugarcane and itch grass (Rottboellia cochinchinensis) plants showing virus-like mosaic symptoms were encountered in farmers’ sugarcane fields in Kaduna State. Symptomatic leaf tissue samples from five randomly selected plants (sugarcane = 4; itch grass = 1) were dried and stored under CaCl2 at room temperature then shipped to Texas A&M AgriLife Research and Extension Center, Weslaco, TX, with USDA-APHIS-PPQ permit (P526P-14-04321) for further analysis. The MagMAX-96 viral RNA isolation kit (Thermo Fisher) was used to isolate total nucleic acid (TNA) from each sample and from a sample subset consisting of pooled leaf tissue materials from both plants. TNA aliquot from the pooled sample was subjected to ribosomal RNA depletion and cDNA library construction using a TruSeq Stranded Total RNA with Ribo-Zero Plant kit (Illumina), then sequenced on the Illumina NextSeq 500 platform. The raw high-throughput sequencing (HTS) reads were analyzed as previously described (Alabi et al. 2015), generating ∼43.5 million Illumina reads (76 nucleotides [nt] in length), of which 31,486 de novo assembled reads mapped to Maize yellow mosaic virus (MaYMV; genus Polerovirus; family Luteoviridae) along with reads mapped to Sugarcane mosaic virus (data not shown). Assembly of the sequence reads (CLC Genome Assembler, Qiagen) yielded 5,566 nt long near complete (∼99%) genome of MaYMV (KY684356) that was 95 to 97% identical and phylogenetically related to corresponding sequences of MaYMV isolates available in GenBank (KU291099–108). To further confirm the occurrence of this virus in source samples, TNA from individual samples were subjected to two-step reverse transcription (RT)-PCR using the Pol-G-F/Pol-G-R primer pair (Knierim et al. 2010). The expected ∼1,100 bp DNA band specific to a region encompassing partial P1-P2 fusion protein and coat protein genes of luteovirids was amplified from three of the five samples (sugarcane = 2; itch grass = 1). The DNA fragment from one sugarcane and the itch grass sample were cloned individually into the pCR2.1 TOPO-TA vector (Life Technologies, Carlsbad, CA) and two independent clones per amplicon sequenced bidirectionally. Pairwise comparisons of sequences from both samples revealed that they shared 99 to 100% nt identity with each other and 97 to 99% identity with the corresponding MaYMV sequences derived by HTS in this study (KY684356), and those retrieved from GenBank (KU291099–108). They also shared 86, 79, and 61% nt identities, respectively, with corresponding sequences of Barley virus G (KT962089), Maize yellow dwarf virus-RMV (KC921392), and Sugarcane yellow leaf virus (AF157029). MaYMV is a recently characterized tentative member of the genus Polerovirus reported from maize in China (Chen et al. 2016). Therefore, our results represent, to the best of our knowledge, the first report of MaYMV in sugarcane and itch grass worldwide and the first report of the virus in an African country. The occurrence of MaYMV in these perennial crop and pernicious weed host have implications for disease epidemiology since both plant species could serve as green bridges for virus perpetuation in cereal production systems.

HETEROSIS OF SOME TROPICAL MAIZE GENOTYPES DERIVED FROM TWO DIFFERENT MAIZE BREEDING ERAS

Heterosis for maize grain yield was studied to identify cross combinations that may be useful sources for inbred line extraction, recurrent selection and, to estimate changes in the maize grain yield heterosis across two breeding eras in the tropics. Field studies were conducted at the International Institute of Tropical Agriculture (IITA), Ibadan during the cropping seasons of 2010, 2011 and 2012, with 10 open pollinated maize varieties (OPVs) derived two breeding eras (1 and 2). The ten OPVs and the crosses generated from them were evaluated under stem borer infested and non-infested, high-N versus low-N and natural conditions. Mid and High-heterosis (MPH &amp; HPH) were estimated from grain yield data from the tested environments. MPH &amp; HPH under natural, optimum N-Fertilizer application, and borer infested environments were 37.20 and 25.38%, 19.85 and 12.3%, 30.98 and 18.94% respectively. Cross combination DMR-LSR-W (Era 1) x TZSR-Y-I (Era 1) expressed the highest magnitude of (MPH &amp; HPH) (97.70 and 87.15%) for grain yield across the tested environments except low-N. It suggest the suitability of the hybrid for cultivation only in environments with high productivity index. Hybrid ACR99TZLCOMP4-DMRSR (Era 1) x BR9928DMRSR (Era 2) had highest HPH under low-N environments. Suggesting this combination as a good source of genes for the development of low nitrogen tolerance maize varieties in the tropics. Cross combinations that expressed better (HPH) under borer infestation are good gene pools for the development of stem borer tolerance maize varieties in stem borer endemic zone. These crosses hold promise as future candidates for commercial exploitation of heterosis or for the extraction of inbred lines in the tropics. Better (HPH) were derived from the crosses between Era 1 and &amp; 2, indicates the older and newer maize varieties complement each other for (HPH) across environments.