Page 18 - SESSION 1 (Graduation e-BOOK)(3 October 2023)

School of Science
FACULTY OF AGRICULTURE,
ENGINEERING & NATURAL SCIENCES

DOCTOR OF PHILOSOPHY
IN SCIENCE

CANDIDATE: MATARANYIKA Natasha P

CANDIDATE’S DISSERTATION
CHARACTERIZATION OF BACTERIAL SYMBIONTS
IN SELECTED DROUGHT-TOLERANT LEGUMES FOR
BIOFERTILISER DEVELOPMENT FOR USE IN NAMIBIA.
The doctoral study was undertaken and completed under the
supervision of Dr. Jean Damascene Uzabakiriho of the University of
Namibia as Main-Supervisor and Professor Percy Chimwamurombe
from the Namibia University of Science and Technology as Co-
Supervisor.

The candidate characterized plant-associated bacteria from five
drought-tolerant legumes grown in Namibia. Identification was done
using 16S rRNA sequencing and bioinformatics. Microbial communities
were assessed using microbiome studies. Characterization was
assessed based on several traits including drought tolerance, nutrient
availability, and fungal disease tolerance. Her study further assessed
several isolates that were found to perform well during lab tests as
bio-inoculants in pilot greenhouse studies. To meet the increasing
food demand, farmers resort to applying harmful chemical fertilizers.
However, there is increasing evidence that arid or semi-arid plant
microbiomes offer beneficial support to plants. In her work, the
candidate presented a comprehensive investigation of the plant
growth-promoting (PGP) microbiomes associated with five legume
species grown in Namibia. These legumes are Vigna unguiculata
(cowpea), V. radiata (mungbean), V. aconitifolia (mothbean),
Macrotyloma uniflorum (horsegram), and Lablab purpureus (Dolichos).
Four new bacterial strains associated with these legumes have been
described.
The results further suggested that the isolated bacteria were endowed
with diverse PGP traits essential in arid environments. Bio-inoculant trials
revealed three strains with over 50% improvement in plant growth. This
presented the first account of the identification and characterization of
beneficial plant-associated bacteria isolated from these arid climate-
tolerant legumes grown in Namibia, as well as the first metagenomic
analyses of plant-associated microbiomes of these legumes.

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