No abstract

Tomatoes are an important agricultural product because they contain high concentrations of bioactive substances, such as folate, ascorbate, polyphenols, and carotenoids, as well as many other essential elements. As a result, tomatoes are thought to be extremely beneficial to human health. Chemical fertilizers and insecticides are routinely utilized to maximize tomato production. In this context, microbial inoculations, particularly those containing PGPR, may be utilized in place of chemical fertilizers and pesticides. In this study, we investigated the effects of PGPR (Bacillus subtilis, and Bacillus amyloliquefaciens) and cyanobacteria when utilized alone, and in conjunction with each other, on the growth, quality, and yield of fresh fruits of tomato plants. The results showed that the inoculation significantly increased all measured parameters of tomato plants compared with the control. Combined use of B. subtilis and B. amyloliquefaciens had a positive impact on tomato yield, increasing fruit yield. Moreover, leaflet anatomical characteristics were altered, with increased thickness of the upper epidermis, lower epidermis, palisade tissue, spongy tissue, and vascular bundles. Tomato fruit quality was improved, as measured by an increased number of fruit per plant (76% increase), fruit weight (g; 33% increase), fruit height (cm; 50% increase), fruit diameter (cm; 50%), total soluble solids (TSS; 26% increase), and ascorbic acid (mg/100 g F.W.; 75% increase), relative to the control, in the first season. In addition, fruit chemical contents (N, P, and K) were increased with inoculation. The results suggest that inoculation with B. subtilis and B. amyloliquefaciens could be successfully used to enhance tomato plant growth and yield.

Gamma rays are known to induce random mutations, which are used to enhance the production of biofilms in bacteria. Therefore, to improve the activity of biofilm formation in wild Bacillus amyloliquefaciens (HM6), this bacterial strain was mutated using five doses of gamma irradiation. Sixteen mutants and their wild strain B. amyloliquefaciens (HM6) were tested for biofilm formation under two different (250 and 350 mM) NaCl concentrations. Only six mutants exhibited a significant increase in biofilm formation under 350 mM NaCl. Inoculation of salt-stressed Giza123 barley seedlings with the two mutants (M1 and M7), which showed distinguishable rep-PCR patterns, and their wild strain significantly decreased MDA content. In addition, such inoculation inhibited POX and CAT activities, while AsA content was increased. The lowest POX and CAT activities, as well as the highest AsA content, were recorded with mutant M7. The full length cDNA of Giza123 APX1 was cloned, sequenced, and submitted to GenBank under accession number MF804856. In BLASTX analysis, its sequence exhibited 99% homology with the Hordeum vulgare peroxisome type ascorbate peroxidase. RT-PCR revealed variable APX1 expression levels in the stressed and nonstressed Giza123 seedlings. Salt stress upregulated the APX1 expression level in uninoculated-stressed seedlings compared to the uninoculated-unstressed ones. On the other hand, inoculation with M1 and M7 mutants and their wild strain modified the APX1 expression level, where the wild and the M1 mutant downregulated the APX1 expression level, while mutant M7 upregulated its expression level under salt stress.

Integrated biofertilizers such as Plant Growth-Promoting Rhizobacteria (PGPRs), cyanobacteria, and yeast can considerably improve the growth, integrity, and overall health of crops, including cowpea. In this study, we assess the benefits of applying microbial fertilizers as an eco-friendly approach to partially substitute chemical fertilizers while maintaining growth and yield characteristics in cowpea plants. We investigated the role of the three microorganisms, Bacillus amyloliquefacien (B), Nostoc mucorum (C), and Saccharomyces cerevisiae (Y), individually and in four possible combinations (B + C, B + Y, C + Y, and B + C + Y) as integrated bio-fertilizers on the microbial enzyme activities, plant growth parameters, and yield characteristics of cowpea. Plants inoculated with B + C + Y mixture resulted in significant improvement in dehydrogenase enzyme activity by 390%, chlorophyll by 180%, plant dry weight by 130%, and in the pod length and dry weight by 68% and 190%, respectively, compared to non-inoculated plants. The grain total carbohydrates increased by 170% over the control due to treatment with B + C + Y. The B + C + Y treatment also positively influenced the anatomy of the terminal leaflet with a 16.6% higher thickness of the midrib zone, 22.6% increase in vascular bundle length, and 42.4% and 33.5% increases in upper and lower epidermal leaf layers, respectively. Additionally, palisade and spongy tissues increased by 36.9% and 26.5%, respectively, compared to the control. An integrated nutrient management program using biofertilizers is recommended for achieving higher yields and environmentally safe cowpea production.