Date of Defense
6-11-2025 9:30 AM
Location
Building F3, Room 222
Document Type
Thesis Defense
Degree Name
Master of Science in Molecular Biology and Biotechnology
College
College of Science
Department
Biology
First Advisor
Prof. Synan F. AbuQamar
Keywords
Actinobacteria; Biofertilizers; Plant growth–promoting rhizobacteria; Rhizosphere competence; Salt tolerance; Sustainable agriculture.
Abstract
Plants are constantly challenged by environmental stresses that restrict their growth and productivity. In the United Arab Emirates (UAE), soil salinity is a critical barrier to agriculture, particularly for tomato (Solanum lycopersicum), which is highly sensitive to moderate salinity levels (>2.5 dS m⁻¹). This study explored the potential of plant growth–promoting rhizobacteria (PGPR), especially actinobacteria, to enhance salt tolerance in tomato. The objective was to evaluate the effeccts of rhizosphere-competent (RC) and non-rhizosphere-competent (NRC) PGPR on plant physiology and yield in saline sandy soils. Actinobacterial strains were isolated from the tomato rhizosphere were screened for the production of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) and plant growth regulators (PGRs). Greenhouse trials under salt stress (200 mM NaCl) examined morphological, physiological, and biochemical responses. Among the isolates, strain #36 (an efficient PGR-producer) and RC isolate #53 (an efficient ACCD producer) were tested individually and in combination. Inoculation with actinobacterial consortia markedly improved shoot and root growth compared with uninoculated controls, with RC consortia consistently outperforming NRC strains under both normal and saline conditions. Strain #36 enhanced growth and photosynthetic efficiency, while its combination with strain #53 provided superior stress tolerance, reducing endogenous ACC levels threefold. This study is the first to demonstrate the synergistic role of RC actinobacterial consortia in alleviating salt stress in tomato. The findings highlight their promise as bioinoculants for sustainable agriculture. By uncovering the mechanisms of PGPR-mediated salinity tolerance, the research offers valuable insights for developing bioinoculant-based strategies to strengthen food security and agricultural sustainability in the UAE.
Included in
ISOLATION AND CHARACTERIZATION OF PLANT GROWTH PROMOTING RHIZOBACTERIA FROM SOILS IN THE UAE AND THEIR EFFECT ON PLANT SALT TOLERANCE
Building F3, Room 222
Plants are constantly challenged by environmental stresses that restrict their growth and productivity. In the United Arab Emirates (UAE), soil salinity is a critical barrier to agriculture, particularly for tomato (Solanum lycopersicum), which is highly sensitive to moderate salinity levels (>2.5 dS m⁻¹). This study explored the potential of plant growth–promoting rhizobacteria (PGPR), especially actinobacteria, to enhance salt tolerance in tomato. The objective was to evaluate the effeccts of rhizosphere-competent (RC) and non-rhizosphere-competent (NRC) PGPR on plant physiology and yield in saline sandy soils. Actinobacterial strains were isolated from the tomato rhizosphere were screened for the production of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) and plant growth regulators (PGRs). Greenhouse trials under salt stress (200 mM NaCl) examined morphological, physiological, and biochemical responses. Among the isolates, strain #36 (an efficient PGR-producer) and RC isolate #53 (an efficient ACCD producer) were tested individually and in combination. Inoculation with actinobacterial consortia markedly improved shoot and root growth compared with uninoculated controls, with RC consortia consistently outperforming NRC strains under both normal and saline conditions. Strain #36 enhanced growth and photosynthetic efficiency, while its combination with strain #53 provided superior stress tolerance, reducing endogenous ACC levels threefold. This study is the first to demonstrate the synergistic role of RC actinobacterial consortia in alleviating salt stress in tomato. The findings highlight their promise as bioinoculants for sustainable agriculture. By uncovering the mechanisms of PGPR-mediated salinity tolerance, the research offers valuable insights for developing bioinoculant-based strategies to strengthen food security and agricultural sustainability in the UAE.