Genome-wide association study reveals genetic architecture and candidate genes for yield and related traits under terminal drought, combined heat and drought in tropical maize germplasm

Open Access Journal; Published online: 15 Feb 2022Maize (Zea mays L.) production is constrained by drought and heat stresses. The combination of these two stresses is likely to be more detrimental. To breed for maize cultivars tolerant of these stresses, 162 tropical maize inbred lines were evaluated under combined heat and drought (CHD) and terminal drought (TD) conditions. The mixed linear model was employed for the genome-wide association study using 7834 SNP markers and several phenotypic data including, days to 50% anthesis (AD) and silking (SD), husk cover (HUSKC), and grain yield (GY). In total, 66, 27, and 24 SNPs were associated with the traits evaluated under CHD, TD, and their combined effects, respectively. Of these, four single nucleotide polymorphism (SNP) markers (SNP_161703060 on Chr01, SNP_196800695 on Chr02, SNP_195454836 on Chr05, and SNP_51772182 on Chr07) had pleiotropic effects on both AD and SD under CHD conditions. Four SNPs (SNP_138825271 (Chr03), SNP_244895453 (Chr04), SNP_168561609 (Chr05), and SNP_62970998 (Chr06)) were associated with AD, SD, and HUSKC under TD. Twelve candidate genes containing phytohormone cis-acting regulating elements were implicated in the regulation of plant responses to multiple stress conditions including heat and drought. The SNPs and candidate genes identified in the study will provide invaluable information for breeding climate smart maize varieties under tropical conditions following validation of the SNP markers

Assessment of the genetic structure and diversity of soybean (Glycine max L.) germplasm using diversity array technology and single nucleotide polymorphism markers

Open Access Journal; Published online: 26 Dec 2021Knowledge of the genetic structure and diversity of germplasm collections is crucial for sustainable genetic improvement through hybridization programs and rapid adaptation to changing breeding objectives. The objective of this study was to determine the genetic diversity and population structure of 281 International Institute of Tropical Agriculture (IITA) soybean accessions using diversity array technology (DArT) and single nucleotide polymorphism (SNP) markers for the efficient utilization of these accessions. From the results, the SNP and DArT markers were well distributed across the 20 soybean chromosomes. The cluster and principal component analyses revealed the genetic diversity among the 281 accessions by grouping them into two stratifications, a grouping that was also evident from the population structure analysis, which divided the 281 accessions into two distinct groups. The analysis of molecular variance revealed that 97% and 98% of the genetic variances using SNP and DArT markers, respectively, were within the population. Genetic diversity indices such as Shannon’s diversity index, diversity and unbiased diversity revealed the diversity among the different populations of the soybean accessions. The SNP and DArT markers used provided similar information on the structure, diversity and polymorphism of the accessions, which indicates the applicability of the DArT marker in genetic diversity studies. Our study provides information about the genetic structure and diversity of the IITA soybean accessions that will allow for the efficient utilization of these accessions in soybean improvement programs, especially in Africa

Enhancing farmers’ access to technology for increased rice productivity in Ghana

A two-year emergency rice (Oryza sativa L.) initiative was launched in 2009 in response to the globalrice crises in 2008. The objective of this initiative in Ghana was to increase rice productivity in order toimprove food security. Project activities included planning sessions, demonstrations, training coursesand community seed production. The project made remarkable progress in enhancing access to qualityseed and fertilizer for over 12,600 farmers while expanding knowledge of best-bet productiontechnologies. Farmers produced 28,663 Mt of paddy which was 16,841 Mt above what they normallyproduced without project intervention. Average yield increased by 92% and also 4,093 women farmersconstituting about 32.4% of the total number of participating farmers benefited directly from the project.Seed fairs, rural radios and audio-visual broadcasts on improved rice production technologies wereused to reach non-participating farmers. The combination of methods that stimulated adoption ofimproved rice production technology was effective in achieving both increased paddy yields andhousehold income. We conclude that investment in rice technology transfer and production effortsduring the two-year period was well justified

Partnership for improved access to agro-inputs and technology: Some experiences from the emergency rice initiative project in Ghana

A two-year emergency rice (Oryza sativa L.) initiative project was launched in 2009 in response to the global rice crisis in 2008. The objective of this initiative in Ghana was to increase rice productivity in order to improve food security. Project activities included seed fairs, dissemination of information on improved production technologies using videos and rural radios, training of agro-input dealers,extension officers and farmers as well as promotion of best-bet practices through field demonstrations.The project made progress in strengthening the ability of agro-input dealers to create business linkages with input suppliers and extend their retail networks to rice farmers. Overall, 34 agro-input dealers were trained, in collaboration with the Ghana Agro-dealer Development project, on agro-input business management, product knowledge and rice production. Thirteen agro-input dealers were assisted to access credit for business development. Better financed, trained agro-dealers were then able to provide over 12,600 rice farmers with improved seed, mineral fertilizers, technical advice on agro-input use and the promotion of improved agronomic practices through field demonstrations. Some agro-input dealers even provided free inputs for the conduct of demonstrations on new products and good agronomic practices. On average, fertilizer application in demonstration trials increased paddy yields by 68 to 80%over the farmer practice of no fertilizer application. For the participating farmers, there were significant increases in rice paddy yields, reductions in the cost of operations and improvements in the contribution of rice to household incomes. The results suggest that a holistic and multi-stakeholder partnership is an efficient way to improve the access by small-holder resource-poor farmers to agro-inputs and technology and also an effective way to grow the rural agro-input marke