AUTHOR=Ojuederie Omena Bernard , Babalola Olubukola Oluranti 

TITLE=Growth enhancement and extenuation of drought stress in maize inoculated with multifaceted ACC deaminase producing rhizobacteria

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=6

YEAR=2023

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2022.1076844

DOI=10.3389/fsufs.2022.1076844

ISSN=2571-581X

ABSTRACT=<sec><title>Introduction</title><p>Maize is a major staple cereal crop grown and consumed globally. However, due to climate change, extreme heat and drought stresses are greatly affecting its production especially in sub-Saharan Africa. The use of a bio-based approach to mitigate drought stress is therefore suggested using plant growth-promoting rhizobacteria (PGPR).</p></sec><sec><title>Methods</title><p>This study investigated the abilities of 1-aminocyclopropane-1-carboxylate (ACC) <italic>deaminase</italic> producing PGPR <italic>Pseudomonas</italic> sp. MRBP4, <italic>Pseudomonas</italic> sp. MRBP13 and <italic>Bacillus</italic> sp. MRBP10 isolated from maize rhizosphere soil, to ameliorate the effect of drought stress in maize genotypes MR44 and S0/8/W/I137TNW//CML550 under two water regimes; mild drought stress (50% FC) and well-watered conditions (100% FC). The rhizobacterial strains were identified by 16S rRNA sequencing and biochemical tests, and evaluated for plant growth-promoting and abiotic stress tolerance traits.</p></sec><sec><title>Results and discussion</title><p>The synergistic effect of the bacterial strains had a highly significant (<italic>p</italic> &lt; 0.001) effect on the total soluble sugar, soil moisture content and relative water content, which were enhanced under water-stress in the inoculated plants. Relative water content was significantly highest (<italic>p</italic> &lt; 0.001) in maize plants co-inoculated with <italic>Pseudomonas</italic> sp. MRBP4 + <italic>Bacillus</italic> sp. MRBP10 (60.55%). Total chlorophyll content was significantly enhanced in maize seedlings sole inoculated with <italic>Pseudomonas</italic> sp. MRBP4, <italic>Pseudomonas</italic> sp. MRBP13, and co-inoculated with <italic>Pseudomonas</italic> sp. MRBP13 + <italic>Bacillus</italic> sp. MRBP10 by 15.91%, 14.99% and 15.75% respectively, over the un-inoculated control. Soil moisture content increased by 28.67% and 30.71% compared to the un-inoculated control when plants were inoculated with <italic>Pseudomonas</italic> sp. MRBP4 + <italic>Bacillus</italic> sp. MRBP10 and <italic>Pseudomonas</italic> sp. MRBP4 + <italic>Bacillus</italic> sp. MRBP10 respectively. The interactive effect of genotype × bacteria significantly enhanced biomass production. Leaf area was highest in maize plants co-inoculated with <italic>Pseudomonas</italic> sp. MRBP4 + <italic>Pseudomonas</italic> sp. MRBP13 (212.45 ± 0.87 cm<sup>2</sup>) under drought stress. Treatment of maize seeds with <italic>Pseudomonas</italic> sp. MRBP 4 + <italic>Pseudomonas</italic> sp. MRBP13 + <italic>Bacillus</italic> sp. MRBP10 significantly increased the root length (10.32 ± 0.48 cm) which enhanced survival of the maize seedlings. Bioinoculation of maize seeds with these strains could boost maize production cultivated in arid regions.</p></sec>