Agricultural Research Knowledge
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- Exploring QTL genes contribute to chickpea ascochyta blight resistance across multiple environments using SSR, DArT and SNP assaysAuthor(s): Hamwieh, Aladdin; Imtiaz, Muhammad; Kemal, Seid Ahmed; Kabbabeh, Siham; Alsamman, Alsamman M.; Istanbuli, Tawffiq (International Library of Sciences)Date: 2024-12-26Type: Journal ArticleStatus: Open accessChickpea (Cicer arietinum L.) occupies the third leading position among grain legumes in cultivated area around the world. Ascochyta blight (AB) caused by Ascochytarabiei (Pass.) Labr. is one of the most destructive foliar diseases of chickpea and can cause complete crop failure in many chickpea growing regions around the world. A recombinant inbred line (RIL) population, comprising 165 lines derived from the cross FLIP98-1065 (R) ILC1929 (S),were evaluated in six environments over three years (2008 – 2011) and three locations in Syria (field and greenhouse locations in Tel Hadya “TH“ and a field location at Lattakia “Lat“). The greenhouse experiments were conducted against AB pathotype II. ANOVA analysis indicated significant differences both among the RILs and among the environments. We produced a total of 1398 (134 SSR, 652 DArTseq and 612 SNP) markers and developed a high-resolution genetic map (1244 markers spanning 2503 cM on eight linkage groups). Three major conserved quantitative trait loci (QTLs) that confer AB resistance were identified: two on linkage group 2 (indicated as LG2-A and LG2-B) and one on linkage group 4 (indicated as LG4). These explain, respectively, a maximum of 18.5%, 11.1% and 25% of the total variation. In total, 18 predicted genes were located in LG4, and 9 and10 predicted genes, respectively, were located in LG2-A and LG2-B. This study presents a first set of SNP markers located within genes associated with AB resistance in chickpea, which could be applied in marker-assisted selection programs for breeding AB-resistant chickpeas.
- Selection of high nitrogen fixation chickpea genotypes under drought stress conditions using multi-environment analysisAuthor(s): Istanbuli, Tawffiq; Alsamman, Alsamman M.; Al-Shamaa, Khaled; Abu Assar, Ahmed; Adlan, Adlan Mohamed Ahmed; Kumar, Tapan; Tawkaz, Sawsan; Hamwieh, Aladdin (Frontiers Media)Date: 2025-04-07Type: Journal ArticleStatus: Open accessChickpea (*Cicer arietinum* L.) is an important pulse crop mainly grown in marginal lands around the world. Drought stress highly impacts symbiotic nitrogen fixation (SNF) in chickpeas, which can limit productivity. Therefore, selecting high nitrogen fixation chickpea genotypes that can tolerate water stress is important for breeding programs. A total of 204 chickpea genotypes were assessed in eight different environments across Lebanon during the 2016 and 2017 growing seasons, under both rainfed and irrigated conditions. The study employed an alpha lattice design with two replications at two distinct locations. Data were collected for yield and nodule characteristics, then subjected to AMMI and GGE biplot analysis. The AMMI analysis indicated that genotype (G), environments (E), and genotype × environment interaction (GEI) had significant effects on grain yield (P < 0.001), highlighting the presence of genetic variation and the potential for selecting stable genotypes. The findings revealed that the environmental effect predominantly influenced chickpea grain yield, with GEI following and G having the least impact. Environment explained 34.5% of the total (G + E + GE) variation, whereas G and GEI captured 16.4% and 24.3%, respectively. According to grain yield (GY), genotype IG70399 demonstrated the highest performance across all environments, while genotype IG8256 displayed the most consistent performance across different conditions. In a rainfed environment, genotype IG73394 had higher nodulation, while IG70384 and IG70410 had higher nodulation biomass (NB) under an irrigated environment. The NB for ten highly tolerant genotypes increased by 24% compared to the two susceptible genotypes under drought stress conditions, while the NB for these ten genotypes increased by 14.6% compared to all studied genotypes.
- Molecular characterization of new causative agents of root rot of wheat in MoroccoAuthor(s): Khalifi, Houda; Bentata, Fatiha; Bouarda, Jamila; El Aissami, Aicha; Niya, Ibtissam; Kahama Issa, Adam; Maafa, Ilyass; Hammoumi, Soukaina; Karim, Sanae; Ibriz, Mohammed; Amrani, Khalid; Brhadda, Najiba; Ziri, Rabea; Labhilili, Mustapha. (Estonian University of Life Sciences)Date: 2024-10-22Type: Journal ArticleStatus: Open accessMost of the world's cereal-growing regions are severely constrained by root rots, crown rot and head blight brought on by Fusarium spp. In Morocco, yield losses due to root rots are not negligible and range from 12 to 14%. For this study, wheat root rot was surveyed in wheat fields from 2014 to 2019 in different regions of Morocco. Diseased plants are less vigorous, show progressive rotting of the root system and produce white or discolored heads containing stunted seeds. Therefore, the improvement of national production goes through the study of this disease on a deep level. To do this, 75 samples have been collected for the morphological study, which made it possible to identify the genus Fusarium present in the roots and the crown of the infected plant, and the molecular study made it possible to characterize the Fusarium species that are present in Moroccan wheat fields. Molecular identification revealed the presence of five Fusarium species, namely: Fusarium culmorum, which is noted as the dominant species in Morocco with a relative frequency of 21%, F. graminearum, F. equiseti, F. avenaccum and finally F. sambucinum, which represented a high rate in the Gharb region.
- Beyond biodiversity: does “Farming with Alternative Pollinators” also boost farmers’ income in wheat (Triticum aestivum L.) fields? a case study in MoroccoAuthor(s): Bencharki, Youssef; Michez, Denis; Smaili, Moulay Chrif; Ihsane, Oumayma; Aw-Hassan, Aden A.; Ssymank, Axel; Rasmont, Pierre; Christmann, Stefanie (Frontiers)Date: 2025-03-13Type: Journal ArticleStatus: Open accessThe importance of flower visitors for ecosystem resilience and crop production underscores the need to address the current decline of flower visitors worldwide. Farming Alternative Pollinators (FAP), economic and ecological benefits of fields hosting various marketable habitat enhancement plants, developed for flower visitors protection in low- and middle-income countries, showed multiple benefits for farmers of pollinator-dependent crops, but potential benefits of FAP for production of pollinator-independent crops have not yet been assessed. Therefore, we conducted in 2021 FAP trials with wheat (Triticum aestivum) as the main crop in two regions of Morocco where cereals are mainly grown in monocultures in field sizes ranging from 2 to 5 ha. We tested the effects of fields adding marketable habitat enhancement plants (MHEP; coriander and canola) versus control fields on pests, natural enemies, flower visitors, and net income. We found significantly lower abundance and diversity of pests in wheat fields using MHEP, but no effect on natural enemy presence or net income. The strips of MHEP attracted a high number of flower visitors in both regions (Settat and Sidi Slimane), they supported flower visitor communities by providing plant resources and alternative habitat in monocultural landscapes extremely degraded for flower visitors.
- Mining genomic regions associated with agronomic and biochemical traits in quinoa through GWASAuthor(s): Rahman, Hifzur; Vikram, Prashant; Hu, Yulan; Asthana, Sugandha; Tanaji, Abhinav; Suryanarayanan, Padmaktshni; Quadros, Chris; Mehta, Lovely; Shahid, Mohammed; Gkanogiannis, Anestis; Thushar, Sumitha; Balazadeh, Salma; Mueller-Roeber, Bernd; Becerra, Augusto; Wei, Tong; Kumar Singh, Rakesh (nature portfolio, 2024-04-22)Date: 2024-04-22Type: Journal ArticleStatus: Open accessQuinoa (Chenopodium quinoa Willd.), an Andean crop, is a facultative halophyte food crop recognized globally for its high nutritional value and plasticity to adapt to harsh conditions. We conducted a genome-wide association study on a diverse set of quinoa germplasm accessions. These accessions were evaluated for the following agronomic and biochemical traits: days to 50% flowering (DTF), plant height (PH), panicle length (PL), stem diameter (SD), seed yield (SY), grain diameter (GD), and thousand-grain weight (TGW). These accessions underwent genotyping-by-sequencing using the DNBSeq-G400R platform. Among all evaluated traits, TGW represented maximum broad-sense heritability. Our study revealed average SNP density of ≈ 3.11 SNPs/10 kb for the whole genome, with the lowest and highest on chromosomes Cq1B and Cq9A, respectively. Principal component analysis clustered the quinoa population in three main clusters, one clearly representing lowland Chilean accessions, whereas the other two groups corresponded to germplasm from the highlands of Peru and Bolivia. In our germplasm set, we estimated linkage disequilibrium decay to be ≈ 118.5 kb. Marker-trait analyses revealed major and consistent effect associations for DTF on chromosomes 3A, 4B, 5B, 6A, 7A, 7B and 8B, with phenotypic variance explained (PVE) as high as 19.15%. Nine associations across eight chromosomes were also found for saponin content with 20% PVE by qSPN5A.1. More QTLs were identified for PL and TGW on multiple chromosomal locations. We identified putative candidate genes in the genomic regions associated with DTF and saponin content. The consistent and major-effect genomic associations can be used in fast-tracking quinoa breeding for wider adaptation across marginal environments.
- Pathogenicity of entomopathogenic Beauveria bassiana strains on Helicoverpa armigera (Hübner)Author(s): Boulamtat, Rachid; El-Fakhouri, Karim; Jaber, Hassna; Oubayoucef, Ali; Ramdani, Chaimae; Fikraoui, Nabil; Al-Jaboobi, Muamar; El Fadil, Meryem; Maafa, Ilyass; Mesfioui, Abdelhalem; Kemal, Seid Ahmed; El Bouhssini, Mustapha (Frontiers Media)Date: 2025-04-11Type: Journal ArticleStatus: Open accessThe destructive pest of chickpeas, Helicoverpa armigera (Hübner), is difficult to control using synthetic insecticides. The current research examined the entomopathogenic and endophytic colonisation effects of three fungal strains of Beauveria bassiana (HASS; RFSL10; SP-IR-566) against H. armigera larvae under laboratory, greenhouse, and field conditions. Four inoculation methods were used in the greenhouse: Root Dipping (RD), Leaf Spraying (LS), Stem Injection (SI), and Seed Coating (SC), while spray application was used for laboratory and field treatments. Under laboratory conditions, the highest entomopathogenic effect was recorded by HASS and RFSL10 strains applied as a direct spray at 108 conidia mL-1 with 100% mortality, followed by SP-IR-566 with 96%, 12 days after treatment. Furthermore, foliar application in the field reduced larval population by an average ranging from 82 to 100%, confirming the significant effects of the three tested strains. In terms of endophytic colonisation under greenhouse setting, both stem injection and root dipping methods expressed low to moderate mortality rates ranging from 32 to 40%, 15 days after application. These findings suggested that B. bassiana strains, investigated as foliar application, had a potential as an effective strategy to control H. armigera. This study also offers new insights into the potential of the endophytic entomopathogens approach as a viable and safe alternative to chemical pesticides.
- The Wheat Seed Sector in the SudanAuthor(s): Bishaw, Zewdie; Turner, Michael; Gizaw, Solomon Assefa; Tahir, Izzat (International Center for Agricultural Research in the Dry Areas (ICARDA), 2017-05-01)Date: 2017-05-01Type: Internal ReportStatus: Open accessThe African Development Bank is currently funding the project “Support to Agricultural Research for Development – Strategic Crops” (SARD-SC), within which twelve countries participate in the wheat sub-project coordinated by ICARDA. These countries are grouped based on an agroclimate, and Sudan provides the ‘hub’ for work in the East African Lowlands. The Agricultural Research Corporation of Sudan (ARC) has a long history and rich experience in wheat research, particularly for breeding heat-tolerant varieties it is therefore well-placed to host this program. Despite this positive research background, the national wheat production in Sudan has decreased in recent years, and this is a serious drain on the economy because of the rising demand for bread and the high cost of imported grain. The government is committed to restoring wheat production and has announced ambitious annual targets. This can be achieved by both productivity gains and an increase in the planted area. The lack of good quality seed is widely regarded as a major factor contributing to the low performance of wheat crops in recent years, and this reflects a wider concern about the overall status of the seed sector. The Government of Sudan requested ICARDA to review the wheat seed sector, identify key constraints, and make recommendations for its revitalization. The inception workshop of the SARD-SC held in March 2013 had already prioritized seed as a key component of technology transfer. Therefore, ICARDA, as the coordinator of the project undertakes this mission with the main focus on wheat but also considers the wider seed issues in Sudan. This dual purpose was emphasised in briefings with senior Ministry officials at the start of the mission. Although the institutional and regulatory aspects of this study are specific to Sudan, the analysis presented in this report may be relevant to other countries within the sub-project because the supply of wheat seed does present some generic challenges that arise from its biological and agronomic characteristics.
- Solar Powered Net-HouseAuthor(s): Nejatian, Arash; Niane, Abdoul Aziz (International Center for Agricultural Research in the Dry Areas (ICARDA), 2024-09-27)Date: 2024-09-27Type: PosterStatus: Open accessSaving Resources, Maximized Yield, Efficient Space Utilization • AC/DC Hybrid Solar-Powered Energy • Closed Hydroponics Systems •Ultra-Low Energy Drippers • Root Zone Cooling •Vertical farming
- Soilless Vertical FarmingAuthor(s): Nejatian, Arash; Niane, Abdoul Aziz (International Center for Agricultural Research in the Dry Areas (ICARDA), 2024-09-29)Date: 2024-09-29Type: PosterStatus: Open accessSince 2002, ICARDA, in collaboration with National Agricultural Research Systems (NARS), has pioneered a high-density vertical soilless cultivation system in the Arabian Peninsula. Tailored for medium-sized farmers, this innovative system is optimized for the production of high-value crops such as herbs, leafy greens, and fruits.
- An Agro-economic comparison between Dwarf and Long green beans production in soilless production systemAuthor(s): Nejatian, Arash; Naqbi, Tahra; Ibrahim, Haliema; Ono, Eiichi (International Center for Agricultural Research in the Dry Areas (ICARDA), 2024-09-28)Date: 2024-09-28Type: PosterStatus: Open accessStudy Objective Compare the yield and income of dwarf and long beans in a hydroponic system in the UAE. Methodology • Randomized Complete Block Design (RCBD) • Dwarf beans (SHADE): Vertical system (60m²) • Long beans (Saphiros): Flat system (120m²) • Location: 8x30m greenhouse at Al Dhaid • Irrigation: Closed Hydroponics System Key Findings Yield: Dwarf beans 1.98 kg/m²; Long beans 0.98 kg/m². Timing: Dwarf beans start earlier and produce one week longer
- Genome-wide analyses of cassava Pathogenesis-related (PR) gene families reveal core transcriptome responses to whitefly infestation, salicylic acid and jasmonic acidAuthor(s): Irigoyen, Maria; Garceau, Danielle; Bohorquez-Chaux, Adriana; Becerra, Augusto; Perez-Fons, Laura; Paul, Fraser; Walling, Linda (BMC)Date: 2020-01-29Type: Journal ArticleStatus: Open accessBackground Whiteflies are a threat to cassava (Manihot esculenta), an important staple food in many tropical/subtropical regions. Understanding the molecular mechanisms regulating cassava’s responses against this pest is crucial for developing control strategies. Pathogenesis-related (PR) protein families are an integral part of plant immunity. With the availability of whole genome sequences, the annotation and expression programs of the full complement of PR genes in an organism can now be achieved. An understanding of the responses of the entire complement of PR genes during biotic stress and to the defense hormones, salicylic acid (SA) and jasmonic acid (JA), is lacking. Here, we analyze the responses of cassava PR genes to whiteflies, SA, JA, and other biotic aggressors. Results The cassava genome possesses 14 of the 17 plant PR families, with a total of 447 PR genes. A cassava PR gene nomenclature is proposed. Phylogenetic relatedness of cassava PR proteins to each other and to homologs in poplar, rice and Arabidopsis identified cassava-specific PR gene family expansions. The temporal programs of PR gene expression in response to the whitefly (Aleurotrachelus socialis) in four whitefly-susceptible cassava genotypes showed that 167 of the 447 PR genes were regulated after whitefly infestation. While the timing of PR gene expression varied, over 37% of whitefly-regulated PR genes were downregulated in all four genotypes. Notably, whitefly-responsive PR genes were largely coordinately regulated by SA and JA. The analysis of cassava PR gene expression in response to five other biotic stresses revealed a strong positive correlation between whitefly and Xanthomonas axonopodis and Cassava Brown Streak Virus responses and negative correlations between whitefly and Cassava Mosaic Virus responses. Finally, certain associations between PR genes in cassava expansions and response to biotic stresses were observed among PR families. Conclusions This study represents the first genome-wide characterization of PR genes in cassava. PR gene responses to six biotic stresses and to SA and JA are demonstrably different to other angiosperms. We propose that our approach could be applied in other species to fully understand PR gene regulation by pathogens, pests and the canonical defense hormones SA and JA.
- Nitrous oxide emissions from cassava fields amended with organic and inorganic fertilizersAuthor(s): Chirinda, Ngonidzashe; Trujillo, Catalina; Loaiza, Sandra; Salazar, Sandra; Luna Melendez, Jorge; Tong Encinas, Liz Alexandra; Becerra, Augusto; Tran, Thierry (Wiley (12 months), 2021-05-18)Date: 2021-01-09Type: Journal ArticleStatus: Timeless limited accessCassava production requires nitrogen (N) inputs to drive processes such as protein synthesis. Nevertheless, N not taken up by cassava roots is subjected to microbial transformation resulting in nitrous oxide (N2O) production, a potent greenhouse gas. The temporal dynamics of soil N is partially influenced by the N source (i.e., organic or inorganic fertilizer) and the synchrony between N supply and demand. This study, which was conducted in Colombia on soils with high organic carbon and phosphorus contents, aimed at monitoring N2O emissions from cassava plots fertilized with organic (49.8 kg N ha-1 year-1) or inorganic fertilizers (22.7 kg N ha-1 year-1). Although the organic fertilizer (vermicompost) contained more than double the amount of N, cumulative N2O emissions from organic cassava production (1.28 kg N2O-N ha-1) were lower than those from inorganic fertilizer-based cassava production (1.74 kg N2O-N ha-1) system. This finding indicates that, if crop yields can be maintained, there is potential to reduce cassava production's environmental impact through organic fertilization on highly fertile soils. However, a transition to organic fertilization depends on the availability of sufficient amounts of organic fertilizers at the farm level. The N2O emissions in this study were higher than those predicted using the default IPCC emission factor, which confirmed the relevance of using country or regional specific emissions factors.
- Conversion and Validation of Uniplex SNP Markers for Selection of Resistance to Cassava Mosaic Disease in Cassava Breeding ProgramsDate: 2021-02-25Type: Journal ArticleStatus: Open accessCassava mosaic disease (CMD) is a major viral disease adversely affecting cassava production in Africa and Asia. Genomic regions conferring resistance to the disease have been mapped in African cassava germplasm through biparental quantitative trait loci (QTL) mapping and genome-wide association studies. To facilitate the utilization of these markers in breeding pipelines to support selections, proof-of-concept technical and biological validation research was carried out using independent pre-breeding and breeding populations. Kompetitive Allele-Specific Polymerase Chain Reaction (KASP) assays were designed from three single nucleotide polymorphism (SNP) markers linked to a major resistance locus on chromosome 12 (S12_7926132, S12_7926163) and a minor locus on chromosome 14 (S14_4626854). The designed assays were robust and easy to score with >99% genotype call rate. The overall predictive accuracy (proportion of true positives and true negatives) of the markers (S12_7926132 and S14_4626854) was 0.80 and 0.78 in the pre-breeding and breeding population, respectively. On average, genotypes that carried at least one copy of the resistant allele at the major CMD2 locus had a significantly higher yield advantage. Nevertheless, variation was observed in prediction accuracies for the major locus (S12_7926132) among sub-families from the two populations, suggesting the need for context-specific utilization, for example, by screening for co-segregation of favorable SNP alleles with resistance in the parents being used for crosses. Availability of these validated SNP markers on the uniplex KASP genotyping platform represents an important step in translational genetics toward marker-assisted selection to accelerate introgression of favorable resistant alleles in breeding populations.
- A simple PCR-based method for the rapid and accurate identification of spider mites (Tetranychidae) on cassavaAuthor(s): Ovalle, Tatiana; Vásquez, Aymer; Jimenez Polo, Jenyfer; Parsa, Soroush; Cuellar, Wilmer; Becerra, Augusto (NATURE RESEARCH)Date: 2020-11-11Type: Journal ArticleStatus: Open accessThe morphological identification of mites entails great challenges. Characteristics such as dorsal setae and aedeagus are widely used, but they show variations between populations, and the technique is time consuming and demands specialized taxonomic expertise that is difficult to access. A successful alternative has been to exploit a region of the mitochondrial cytochrome oxidase I (COI) gene to classify specimens to the species level. We analyzed the COI sequences of four mite species associated with cassava and classified them definitively by detailed morphological examinations. We then developed an identification kit based on the restriction fragment length polymorphism–polymerase chain reaction of subunit I of the COI gene focused on the three restriction enzymes AseI, MboII, and ApoI. This set of enzymes permitted the simple, accurate identification of Mononychellus caribbeanae, M. tanajoa, M. mcgregori, and Tetranychus urticae, rapidly and with few resources. This kit could be a vital tool for the surveillance and monitoring of mite pests in cassava crop protection programs in Africa, Asia, and Latin America.
- Exploring the chemotypes underlying important agronomic and consumer traits in cassava (Manihot esculenta crantz)Author(s): Drapal, Margit; Ovalle, Tatiana; Becerra, Augusto; Paul, Fraser (Elsevier (12 months), 2020-08-01)Date: 2020-05-26Type: Journal ArticleStatus: Timeless limited accessA broad diversity of phenotypes are available within the cassava germplasm collections. The phenotypes include improved nutritional, starch or culinary root quality as well as abiotic and biotic resistance properties. Some of these traits can be found naturally occurring in cassava landraces, whereas others are the result of targeted breeding efforts. For future breeding programmes it is important to know the underlying mechanisms of these desirable traits. Metabolomics can assist in the elucidation of these mechanisms by measuring the end products of the cellular processes conferring the traits of interest. The present study focused on the comparison of two or more variants of the same trait such as high and low culinary quality or resistance and susceptibility to thrips. Overall, eight different traits were assessed. Results showed that amino acids and umami compounds were associated with superior culinary attributes and the phenylpropanoid superpathway plays an important role in pest resistance. Furthermore, the data highlighted a low chemodiversity in African cassavas and that the source-sink relation was still active at the harvest stage.
- Toward better understanding of postharvest deterioration: biochemical changes in stored cassava (Manihot esculenta Crantz) rootsAuthor(s): Gavicho Uarrota, Virgilio; da Costa Nunes, Eduardo; Martins Peruch, Luiz Augusto; de Oliveira Neubert, Enilto; Coelho, Bianca; Moresco, Rodolfo; Dominguez, Moralba; Sanchez, Teresa; Luna Melendez, Jorge; Dufour, Dominique; Ceballos, Hernan; Becerra, Augusto; Hershey, Clair; Rocha, Miguel; Maraschin, Marcelo (Wiley Open Access, 2016-05-01)Date: 2015-10-26Type: Journal ArticleStatus: Open accessFood losses can occur during production, postharvest, and processing stages in the supply chain. With the onset of worldwide food shortages, interest in reducing postharvest losses in cassava has been increasing. In this research, the main goal was to evaluate biochemical changes and identify the metabolites involved in the deterioration of cassava roots. We found that high levels of ascorbic acid (AsA), polyphenol oxidase (PPO), dry matter, and proteins are correlated with overall lower rates of deterioration. On the other hand, soluble sugars such as glucose and fructose, as well as organic acids, mainly, succinic acid, seem to be upregulated during storage and may play a role in the deterioration of cassava roots. Cultivar Branco (BRA) was most resilient to postharvest physiological deterioration (PPD), while Oriental (ORI) was the most susceptible. Our findings suggest that PPO, AsA, and proteins may play a distinct role in PPD delay.
- DNA fingerprinting reveals varietal composition of Vietnamese cassava germplasm (Manihot esculenta Crantz) from farmers’ field and genebank collectionsAuthor(s): Ocampo, John; Ovalle, Tatiana; Antonio Labarta, Ricardo; Le, Dung; de Haan, Stefan; Nguyen, Vu; Quy Kha, Le; Becerra, Augusto (Springer (part of Springer Nature), 2022-06-01)Date: 2021-02-25Type: Journal ArticleStatus: Open accessCassava is the most important smallholder cash crops in Southeast Asia and is especially used in industrial products. Yet, systematic genetic studies on molecular markers from Vietnamese germplasm have not been considered for breeding and conservation programs. We conducted a molecular analysis of 1570 clones of cassava germplasm from farms across six agro-ecological zones using informative SNP markers. We unraveled the genetic diversity and population structure and provided insights into the value of breeding and conservation programs. Duplicated genotypes comprised 98% of the total sample of the Central Highlands region. Ninety-six SNPs were amplified Central Highlands and South East provinces had the highest allelic richness, covering up to 83% of alleles. The average observed heterozygosity (Ho = 0.43) was slightly higher than expected (He = 0.40) across SNP markers, suggesting an excess of heterozygotes plants. Diversity indexes indicated that cassava populations from North West and Eastern Vietnam are genetically diverse (mean He = 0.40). Genetic parentage tests identified 85 unique genetic groups within the varieties KM94, KM419, BRA1305, KM101, KM140, PER262, KM60, KM57 and two unidentified varieties, which accounted for 82% of the frequency distribution. KM94 is the most dominant variety in Vietnamese farms surveyed (38%), reflecting its superior quality and productivity. Discriminant analysis of principal components (DAPC) revealed four main subgroups, which were partially corroborated by neighbor joining (NJ) analyses. After removing duplicates, 31 unique genotypes were distributed across five of the agro-ecological zones. These were well distributed in the subgroups revealed via DAPC and NJ analyses. The genetic groups identified herein could be used to select unique accessions that should ideally conform with ex situ germplasm collections and identify areas where on-farm conservation programs should be targeted. Newly identified genotypes may also contribute as genetic breeding resources that could be used to adapt cassava to future changes and farmers’ needs.
- Modeling growth, development and yield of cassava: A reviewAuthor(s): Moreno Cadena, Leidy Patricia; Hoogenboom, Gerrit; Cock, James; Ramirez-Villegas, Julian; Pypers, Pieter; Kreye, Christine; Tariku, Meklit; Ezui, Kodjovi; Becerra, Augusto; Asseng, Senthold (Elsevier (12 months), 2021-06-15)Date: 2021-04-12Type: Journal ArticleStatus: Open accessCassava is an important crop in the developing world. The goal of this study was to review published cassava models (18) for their capability to simulate storage root biomass and to categorize them into static and dynamic models. The majority (14) are dynamic and capture within season growth dynamics. Most (13) of the dynamic models consider environmental factors such as temperature, solar radiation, soil water and nutrient restrictions. More than half (10) have been calibrated for a distinct genotype. Only one of the four static models includes environmental variables. While the static regression models are useful to estimate final yield, their application is limited to the locations or varieties used for their development unless recalibrated for distinct conditions. Dynamic models simulate growth process and provide estimates of yield over time with, in most cases, no fixed maturity date. The dynamic models that simulate the detailed development of nodal units tend to be less accurate in determining final yield compared to the simpler dynamic and statistic models. However, they can be more safely applied to novel environmental conditions that can be explored in silico. Deficiencies in the current models are highlighted including suggestions on how they can be improved. None of the current dynamic cassava models adequately simulates the starch content of fresh cassava roots with almost all models based on dry biomass simulations. Further studies are necessary to develop a new module for existing cassava models to simulate cassava quality.
- Identifying New Resistance to Cassava Mosaic Disease and Validating Markers for the CMD2 LocusAuthor(s): Cu, Thuy; Becerra, Augusto; Nguyen, Vu; Huu Hy, Nguyen; Pham, Nhan; Ceballos, Hernan; Newby, Jonathan; Tung, Nguyen; Nguyen, Trong; Tuan, Le; Hung, Nguyen Hung; Hanh, Nguyen; Trang, Do; Ha, Pham; Ham, Le Huy; Pham, Xuan; Quynh, Do; Rabbi, Ismail; Kulakow, Peter; Zhang, Xiaofei (Multidisciplinary Digital Publishing Institute (MDPI))Date: 2021-08-30Type: Journal ArticleStatus: Open accessCassava (Manihot esculenta Crantz) is a crucial staple crop, and provides carbohydrate energy to more than half a billion people in the tropics. Cassava mosaic disease (CMD) is the most important disease of cassava in Africa. Since Sri Lanka Cassava Mosaic Virus (SLCMV) was first reported in South East Asia in 2015, establishing sustainable solutions to CMD has become a top priority for the cassava program at the International Center for Tropical Agriculture (CIAT) and its partners. In the present study, we screened two populations for CMD resistance: VNM142, 142 clones collected from farms throughout Vietnam, and CIAT102, 102 clones resistant to CMD or mites, which were introduced from CIAT. High broad-sense heritability was observed in all the trials (>0.80). From the population VNM142, eight clones showed high CMD resistance with CMD severity scores less than 2.0. Two resistant clones had the same DNA fingerprinting with the accessions CR63 (PER262 or TAI9) and KM57 (VNM8) in the genebank, respectively. To our knowledge, this is the first report of CMD resistance in the genebank at CIAT. We also used the two populations to validate the CMD markers S12_7926132 and S14_4626854. Both markers explained 51% of the population variance in the segregating population CIAT102, but only 11% in the diverse population VNM142. Thus, we concluded that the two CMD markers could not be used to select for CMD resistance in diverse populations, but could predict the CMD resistance in segregating populations when the susceptible parents do not have resistant marker alleles and the resistance of the CMD2 donors is confirmed.
- Cassava mosaic disease and its management in Southeast AsiaAuthor(s): Uke, Ayaka; Tokunaga, Hiroki; Utsumi, Yoshinori; Nguyen, Vu; Pham, Nhan; Srean, Pao; Huu Hy, Nguyen; Ham, Le Huy; Becerra, Augusto; Ishitani, Manabu; Hung, Nguyen Hung; Tuan, Le; Van Hong, Nguyen; Quang Huy, Ngo; Xuan Hoat, Trinh; Takasu, Keiji; Seki, Motoaki; Ugaki, Masashi (Springer (part of Springer Nature), 2022-06-01)Date: 2021-07-09Type: Journal ArticleStatus: Open accessCassava (Manihot esculenta Crantz) is one of the most important edible crops in tropical and subtropical regions. Recently, invasive insect pests and diseases have resulted in serious losses to cassava in Southeast Asia. In this review we discuss the current outbreak of cassava mosaic disease (CMD) caused by the Sri Lankan cassava mosaic virus (SLCMV) in Southeast Asia, and summarize similarities between SLCMV and other cassava mosaic begomoviruses. A SATREPS (Science and Technology Research Partnership for Sustainable Development) project “Development and dissemination of sustainable production systems based on invasive pest management of cassava in Vietnam, Cambodia and Thailand”, was launched in 2016, which has been funded by The Japan International Cooperation Agency (JICA) and The Japan Science and Technology Agency (JST), Japan. The objectives of SATREPS were to establish healthy seed production and dissemination systems for cassava in south Vietnam and Cambodia, and to develop management systems for plant diseases and insect pests of cassava. To achieve these goals, model systems of healthy seed production in Vietnam and Cambodia have been developed incorporating CMD-resistant planting materials through international networks with The International Center for Tropical Agriculture (CIAT) and The International Institute of Tropical Agriculture (IITA).