https://hdl.handle.net/10646/195 2026-04-10T07:56:44Z 2026-04-10T07:56:44Z Kamutando, Casper N Magorokosho, Cosmos Dari, Shorai https://hdl.handle.net/10646/4764 2025-11-14T01:15:43Z 2018-02-15T00:00:00Z

Combining ability for grain yield performance among CIMMYT germplasm adapted to the mid-altitude conditions Kamutando, Casper N; Magorokosho, Cosmos; Dari, Shorai The International Centre for Maize and Wheat Improvement (CIMMYT) develops maize (Zea mays L.) inbred lines and hybrids yearly that have several breeding and commercial attributes. However, no genetic analysis has been done on the recently developed inbred lines for yield performance under drought and low-N stress. The objectives of this study were to identify lines with positive general combining ability (GCA) effects for grain yield under stress environments and to identify the best single-cross hybrids with the highest specific combining ability (SCA) effects. Analysis of variance combined across sites showed significant mean squares for genotypes, locations and genotype by environment interaction (GEI) for grain yield. GCAlines, SCA and components of interaction effects were significant across sites. Additive genetic variance was more important than dominance variance in determining yield performance across locations indicating that selection based on grain yield under drought and low-N stress can be effective. Average grain yield across the eight locations ranged from 1.61 t ha-1 to 10.63 t ha-1 while narrow sense heritability for grain yield was 52.6% across sites and was slightly lower under managed drought and low-N stress. The testers CL115807 and CL106622 showed positive and significant GCA effects for yield performance under drought and low-N stress respectively. The best tester across all sites was CL115793 and line CZL0713 had consistently positive GCA effects for grain yield across sites. CML536 × CL115802 and CML312 × CL106508 were the best single crosses under low nitrogen stress sites while hybrid CML312 × C323-45 showed the highest positive SCA effects across sites. In conclusion, our results show that CIMMYT has new lines that have desirable adaptive attributes when grown under drought and low nitrogen stress environments in the mid-altitude region; hence these can be adopted for hybrid, synthetic and OPV formation.

2018-02-15T00:00:00Z Le Roux, Johannes, J. Crous, Padro, W. Kamutando, Casper, Nyaradzai Richardson, David, M. Strasberg, Dominique Wingfield, Michael, J. Wright, Mark, G. Valverde, Angel https://hdl.handle.net/10646/4610 2023-12-13T01:12:23Z 2021-09-01T00:00:00Z

A core of rhizosphere bacterial taxa associates with two of the world’s most isolated plant congeners. Le Roux, Johannes, J.; Crous, Padro, W.; Kamutando, Casper, Nyaradzai; Richardson, David, M.; Strasberg, Dominique; Wingfield, Michael, J.; Wright, Mark, G.; Valverde, Angel Understanding the contributions of abiotic and biotic conditions to soil microbial diversity, structure, and function, remains a central focus in soil biology and biogeochemistry. Here we aim to determine how geography and host plant identity influence these different components of rhizosphere bacterial communities and endosymbionts associated with Acacia heterophylla on Réunion island (Mascarene archipelago, Indian Ocean) and A. koa in the Hawaiian Islands (Hawaiian archipelago, Pacific Ocean). These two tree species are remarkable: they are each other’s closest living relatives despite their habitats being more than 16 000 km apart.

2021-09-01T00:00:00Z Kamutando, Casper, Nyaradzai Surendra, Vikram Nkuekam, Gilbert, Kamgan Makhalanyane, Thulani, P. Greve, Johannes, J. Richardson, David, M. Cowan, David, M. Valverde, Angel https://hdl.handle.net/10646/4609 2023-12-13T01:12:23Z 2019-01-01T00:00:00Z

The functional potential of the rhizospheric microbiome of an invasive tree species, acacia dealbata. Kamutando, Casper, Nyaradzai; Surendra, Vikram; Nkuekam, Gilbert, Kamgan; Makhalanyane, Thulani, P.; Greve, Johannes, J.; Richardson, David, M.; Cowan, David, M.; Valverde, Angel Plant-microbe interactions mediate both the invasiveness of introduced plant species and the impacts that they have in invaded ecosystems. Although the phylogenetic composition of the rhizospheric microbiome of Acacia dealbata (an invasive Australian tree species) has been investigated, little is known about the functional potential of the constituents of these altered microbial communities. We used shotgun DNA sequencing to better understand the link between bacterial community composition and functional capacity in the rhizospheric microbiomes associated with invasive A. dealbata populations in South Africa. Our analysis showed that several genes associated with plant growth-promoting (PGP) traits were significantly overrepresented in the rhizospheric metagenomes compared to neighbouring bulk soils collected away from A. dealbata stands. The majority of these genes are involved in the metabolism of nitrogen, carbohydrates and vitamins, and in various membrane transport systems. Overrepresented genes were linked to a limited number of bacterial taxa, mostly Bradyrhizobium species, the preferred N-fixing rhizobial symbiont of Australian acacias. Overall, these findings suggest that A. dealbata enriches rhizosphere soils with potentially beneficial microbial taxa, and that members of the genus Bradyrhizobium may play an integral role in mediating PGP processes that may influence the success of this invader when colonizing novel environments

2019-01-01T00:00:00Z Kamutando, Casper N Nkuekam, Gilbert, Kamgan Surendra, Vikram Makhalanyane, Thulani, P. Greve, Michelle Le Roux, Johannes, J. Richardson, David, M. Cowan, Don https://hdl.handle.net/10646/4558 2023-05-29T01:11:59Z 2017-07-26T00:00:00Z

Soil nutritional status and biogeography influence rhizosphere microbial communities associated with the invasive tree Acacia dealbata Kamutando, Casper N; Nkuekam, Gilbert, Kamgan; Surendra, Vikram; Makhalanyane, Thulani, P.; Greve, Michelle; Le Roux, Johannes, J.; Richardson, David, M.; Cowan, Don Invasiveness and the impacts of introduced plants are known to be mediated by plant-microbe interactions. Yet, the microbial communities associated with invasive plants are generally poorly understood. Here we report on the first comprehensive investigation of the bacterial and fungal communities inhabiting the rhizosphere and the surrounding bulk soil of a widespread invasive tree, Acacia dealbata. Amplicon sequencing data indicated that rhizospheric microbial communities differed significantly in structure and composition from those of the bulk soil. Two bacterial (Alphaproteobacteria and Gammaproteobacteria) and two fungal (Pezizomycetes and Agaricomycetes) classes were enriched in the rhizosphere compared with bulk soils. Changes in nutritional status, possibly induced by A. dealbata, primarily shaped rhizosphere soil communities. Despite a high degree of geographic invasive tree. dealbata populations shared a core of bacterial and fungal taxa, some of which are known to be involved in N and P cycling, while others are regarded as plant pathogens. I also showed that several functional genes related to plant growth promotion were overrepresented in the rhizospheres of A. dealbata. Overall, results suggest that rhizosphere microbes may contribute to the widespread success of this invader in novel environments.

2017-07-26T00:00:00Z