ABSTRACT
This study reports the diversity of cultivable endophytic bacteria associated with yellow iris (Iris pseudacorus L.) by using 16S rRNA gene analysis and their plant beneficial traits. The 16S rRNA sequence similarities of endophytic bacteria isolated from the leaves and roots of yellow iris showed that the isolates belonged to the genera Staphylococcus, Streptomyces, Variovorax, Pantoea, Paenibacillus, Bacillus, Janthinobacterium, Enterobacter, Brevibacterium, Agrobacterium, Rhizobium, Xanthomonas translucens, and Pseudomonas. The endophytic bacteria Pseudomonas gessardii HRT18, Brevibacterium frigoritolerans HRT8, Streptomyces atratus HRT13, and Bacillus toyonensis HST13 exhibited antimicrobial activity against five plant pathogenic fungi Fusarium, Rhizoctonia, Botrytis, Pythium, and Alternaria. They also demonstrated the capability to produce chitinase, protease, glucanase, lipase, HCN, and indole-3-acetic acid (IAA). Thirteen isolates (46%) produced IAA, and the most active IAA producers were Bacillus cereus, Agrobacterium tumefaciens, Agrobacterium vitis, Bacillus megaterium, and Bacillus aryabhattai. The IAA producing bacterial isolates stimulated root and shoot growth of garden cress. Our findings suggest that medicinal plants could be a promising source for isolating plant-beneficial bacteria that can be used to enhance the growth and protect plants against soil-borne pathogens.
ABSTRACT
The diversity of salt-tolerant cultivable endophytic bacteria associated with the halophyte New Zealand spinach (Tetragonia tetragonioides (Pall.) Kuntze) was studied, and their plant beneficial properties were evaluated. The bacteria isolated from leaves and roots belonged to Agrobacterium, Stenotrophomonas, Bacillus, Brevibacterium, Pseudomonas, Streptomyces, Pseudarthrobacter, Raoultella, Curtobacterium, and Pantoea. Isolates exhibited plant growth-promoting traits, including the production of a phytohormone (indole 3-acetic-acid), cell wall degrading enzymes, and hydrogen cyanide production. Furthermore, antifungal activity against the plant pathogenic fungi Fusarium solani, F. oxysporum, and Verticillium dahliae was detected. Ten out of twenty bacterial isolates were able to synthesize ACC deaminase, which plays a vital role in decreasing ethylene levels in plants. Regardless of the origin of isolated bacteria, root or leaf tissue, they stimulated plant root and shoot growth under 200 mM NaCl conditions. Our study suggests that halophytes such as New Zealand spinach are a promising source for isolating halotolerant plant-beneficial bacteria, which can be considered as potentially efficient biofertilizers in the bioremediation of salt-affected soils.
ABSTRACT
Hydrochar is rich in nutrients and may provide a favorable habitat or shelter for bacterial proliferation and survival. Therefore, in this study, we investigate the efficiency of a hydrochar-based rhizobial inoculant (Bradyrhizobium japonicum) on the symbiotic performance of soybean under both greenhouse and field conditions. There were positive and significant effects of hydrochar-based inoculation on the root and shoot growth of soybean as compared to uninoculated plants grown under irrigated and drought conditions. The drought stress significantly inhibited the symbiotic performance of rhizobia with soybean. Soybean inoculated with hydrochar-based B. japonicum produced twofold more nodules under drought stress conditions as compared to plants inoculated with a commercial preparation/inoculant carrier B. japonicum (HISTICK). The N concentration of inoculated plants with hydrochar-based B. japonicum was by 31% higher than that of un-inoculated plants grown in pots and by 22% for HISTICK. Furthermore, the soybean treated with hydrochar-based B. japonicum showed higher grain yield of 29% under irrigated conditions and 40% higher under rainfed condition compared to un-inoculated plants. In conclusion, the obtained results proved the potential of hydrochar-based B. japonicum inoculant for soybean in terms of increased symbiotic performance and agronomic traits, especially under rainfed conditions.
ABSTRACT
BACKGROUND: Lycopene (LYC) is a natural carotenoid with powerful reactive oxygen species (ROS) scavenging activities. The aim of this study was to investigate if lycopene has the ability to reverse ROS-mediated alterations to the motility, viability and intracellular antioxidant profile of bovine spermatozoa subjected to ferrous ascorbate (FeAA). Spermatozoa were washed out of fresh bovine semen, suspended in 2.9 % sodium citrate and subjected to LYC treatment (0.25, 0.5, 1 or 2 mmol/L) in the presence or absence of FeAA (150 µmol/L FeSO4 and 750 µmol/L ascorbic acid) during a 6 h in vitro culture. Spermatozoa motion characteristics were assessed using the SpermVision™ computer-aided sperm analysis (CASA) system. Cell viability was examined with the metabolic activity (MTT) assay, ROS generation was quantified via luminometry and the nitroblue-tetrazolium (NBT) test was applied to quantify the intracellular superoxide formation. Cell lysates were prepared at the end of the in vitro culture to investigate the intracellular activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) as well as the concentrations of glutathione (GSH) and malondialdehyde (MDA). RESULTS: FeAA treatment led to a reduced spermatozoa motility (P < 0.001), viability (P < 0.001) and a decline of the antioxidant capacity of spermatozoa (P < 0.001) but increased the ROS generation (P < 0.001), superoxide production (P < 0.001) and lipid peroxidation (P < 0.001). LYC administration resulted in a preservation of the spermatozoa motion parameters (P < 0.001), mitochondrial activity (P < 0.001) and antioxidant characteristics (P < 0.001 with respect to SOD; P < 0.01 in relation to CAT; P < 0.05 as for GPx and GSH) with a concentration range of 1 and 2 mmol/L LYC revealed to be the most effective. CONCLUSIONS: Our results suggest that LYC exhibits significant ROS-scavenging and antioxidant properties which may prevent spermatozoa alterations caused by oxidative stress, and preserve the functionality of male reproductive cells.
