Application of Plant Growth-Promoting Bacteria from Cape Verde to Increase Maize Tolerance to Salinity

Inducing Drought Resilience in Maize Through Encapsulated Bacteria: Physiological and Biochemical Adaptations

Droughts are projected to become prevalent throughout the 21st century, endangering agricultural productivity and global food security. To address these challenges, novel strategies to enhance water management and augment plant resilience are imperative. Bacterial encapsulation has emerged as a promising approach, offering benefits such as enhanced bacterial survival, soil compatibility, and sustainable plant growth. This study evaluated the osmotolerance of bacteria from arid environments and determined their plant growth-promoting ability in drought conditions. The encapsulation of these bacteria in bio-compatible capsules led to a substantial enhancement in the performance of maize plants under drought stress. Maize plants treated with encapsulated bacteria demonstrated a 35% increase in root biomass and a 28% enhancement in shoot growth compared to untreated controls. Furthermore, significant physiological and biochemical adaptations were observed, including a 45% increase in photosynthetic pigment concentration and higher osmolyte levels, which contributed to improved drought stress tolerance. The findings of this study demonstrate the potential of encapsulated bacteria to enhance maize resilience to drought, thereby supporting robust growth under water-limited conditions. This approach presents a sustainable strategy to improve drought tolerance, and it may reduce irrigation dependency and maintain crop yields in the face of increasing climate uncertainty.

Biodegradable Microplastics from Agricultural Mulch Films: Implications for Plant Growth-Promoting Bacteria and Plant's Oxidative Stress

This study explores the interactions between biodegradable (BIO) microplastics and plant growth-promoting bacteria (PGPB), assessing their effects on soil health and crop productivity. Five bacterial strains, Bacillus, Enterobacter, Kosakonia, Rhizobium, and Pseudomonas, were exposed to BIO microplastics to examine strain-specific responses. This study revealed that while most bacteria experienced growth inhibition, Kosakonia sp. O21 was poorly affected by BIO microplastics, indicating a potential for microplastic degradation. This study further investigated the effect of these microplastics on plant growth and biochemistry. Results showed that exposure to BIO microplastics significatively reduced plant growth and caused oxidative stress, affecting membranes and proteins and inducing the activity of glutathione S-transferases (GSTs), catalase (CAT), and superoxide dismutase (SOD) as antioxidant responses. Bacterial inoculation alleviated plant oxidative stress, especially at lower concentrations of microplastics. These findings emphasize the critical role of oxidative stress in mediating the negative effects of BIO microplastics on plants and the relevance of bacterial strains that can tolerate BIO microplastics to protect plants from BIO microplastics' effects. Results also highlight the importance of extending research to assess the long-term implications of biodegradable microplastics for soil PGPBs and plant health and crop productivity. This study contributes to sustainable agricultural practices by offering insights into mitigating the risks of microplastic pollution through microbial-based interventions.

Pseudoxanthomonas sp. JBR18, a halotolerant endophytic bacterium, improves the salt tolerance of Arabidopsis seedlings

Salinization of land is globally increasing due to climate change, and salinity stress is an important abiotic stressor that adversely affects agricultural productivity. In this study, we assessed a halotolerant endophytic bacterium, Pseudoxanthomonas sp. JBR18, for its potential as a plant growth-promoting agent with multiple beneficial properties. The strain exhibited tolerance to sodium chloride concentration of up to 7.5 % in the R2A medium. In vitro evaluation revealed that strain JBR18 possessed proteolytic, protease (EC 3.4), and cellulase (EC 3.2.1.4) activities, as well as the ability to produce indole-acetic acid, proline, and exopolysaccharides. Compared with the controls, co-cultivation of Arabidopsis seedlings with the strain JBR18 improved plant growth, rosette size, shoot and root fresh weight, and chlorophyll content under salinity stress. Moreover, JBR18-inoculated seedlings showed lower levels of malondialdehyde, reactive oxygen species, and Na+ uptake into plant cells under salt stress but higher levels of K+. Additionally, seedlings inoculated with JBR18 exhibited a delayed response time and quantity of salt-responsive genes RD29A, RD29B, RD20, RD22, and KIN1 under salt stress. These multiple effects suggest that Pseudoxanthomonas sp. JBR18 is a promising candidate for mitigating the negative impacts of salinity stress on plant growth. Our findings may assist in future efforts to develop eco-friendly strategies for managing abiotic stress and enhancing plant tolerance to salt stress.