Characterization of bacterial diversity between two coastal regions with heterogeneous soil texture.

Studying microbial diversity and the effects of external factors on the microbiome could expand our understanding of environmental alterations. Silt and sand are mineral particles that form soil texture and even though most of the soils on earth contain a fraction of them and some other soils form almost by them, their effects on the microbiome remained to elucidate. In this study, the bacterial biodiversity of sand and silt clay soils was investigated. Furthermore, their effects on plant growth have been determined. Our data showed that biodiversity and biomass of microbiome are higher in silt-based soil. It is interesting that the pseudomonas genera only exist in silt-based soil while it is in the absence of sand-based soil. In contrast, B. thuringiensis could be found in sand-based soil while it is not found in silt texture. Our data also demonstrated that there are no significant changes in stress response between the two groups however, differential physiological changes in plants inoculated with silt and sand based bacterial isolates have been observed. This data could indicate that smaller size particles could contain more bacteria with higher biodiversity due to providing more surfaces for bacteria to grow.

Bacterial diversity changes in response to an altitudinal gradient in arid and semi-arid regions and their effects on crops growth.

The microbiome of soil has a fundamental role in maintaining the health of soil and plants. While the diversity of microbes is one of the most important factors in the environment, little is known about the effects of elevation on the microbiome and the impact of the affected microbiome on plants. The main goal of this study is to expand our knowledge of what happens to the soil bacterial community along an altitudinal gradient and investigate their possibly different impacts on plant growth. Bacteria from soils at various altitudes have been isolated, characterized, and identified by Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) to determine the effects of an elevational gradient on the microbiome and plant growth. Furthermore, their effects have been investigated by isolates assessment on maize, wheat, and canola. Based on our results, higher altitude results in a higher diversity of the microbiome and lower bacteria biomass. Bacillus cereus is found in abundance in arid and semi-arid samples. Interestingly, enhanced diversity in higher altitudes shows similarity in response to environmental stress and tolerates these factors well. Furthermore, the inoculation of these bacteria could enhance the overall growth of plants. We prove that bacterial communities could change their biomass and diversity in response to altitude changes. These indicate evolutionary pressure as these bacteria could tolerate stress factors well and have a better relationship with plants.

Maize growth response to different Bacillus strains isolated from a salt-marshland area under salinity stress.

Maize (Zea mays) growth performance has been hindered due to the high soil salinity. Salinity is one of the most severe abiotic stresses that has led to growth imbalance and profitability of harvests in arid and semi-arid regions. Plants have taken advantage of salt-tolerant bacteria as plant growth-promoters to enhance growth and reduce the adverse effects of salinity through the regulation of some biochemical, physiological, and molecular features. Preferences for non-chemical, eco-friendly, and economical approaches have caused the inquiry of the Bacillus genus as a joint group of plant growth-promoting rhizobacteria known to alleviate salt-stress impacts. In the present study, halotolerant Bacillus strains were isolated from salt-marshland soil and characterized for their physiological, molecular, and biochemical properties. Twenty-four bacterial isolates collected from high saline fields of salt marshland were analyzed by MALDI-TOF MS proteome analysis, which confirmed the taxonomic affiliation with Bacillus cereus, Bacillus subtilis, Bacillus atrophaeus, and Bacillus thorngiensis. Applying the isolates on maize plants as bio-inoculant bacteria obviously increased the growth parameters (P < 0.01). Pot experiments showed that isolates 74 and 90 were the most prominent strains to minimize the harmful effects of salinity. Its effects are heightening the potassium/sodium ratio and K-Na selectivity in shoots and roots measured by flame atomic absorption photometry (AAS). Accordingly, Bacillus cereus isolate 74 showed a maximum increase in dry weights of the shoot (133.89%), root (237.08%), length of the shoot (125%), and root (119.44%) compared to the control condition. Our findings suggest that bacteria isolated from marshland may be an economical and simple means to increase plant growth and resistance to high salinity soil conditions.

Energy Flow from Root to Shoot: A Comprehensive In silico Analysis.

BACKGROUND: Root to shoot connection and transfer of information seems to be taken place mostly via the transmissions of signal molecules, secondary metabolites, amino acids, hormones and proteins, through xylem sap. Examination of earlier reports is indicative of relatively high levels of conservation in xylem sap protein compositions. Apparently these protein molecules are being synthesized in roots in response to environmental changes and get transported to aerial plant parts after secretion into xylem sap. OBJECTIVES: In order to comprehend this so-called passive signaling, some questions need to be answered: 1) Do these proteins have the capability to act as signals? 2) How much energy does root spend for the biosynthesis of the secreted proteins? How similar is the amount of energy that root cells spent for the biosynthesis of intra- and extra-cellular proteins? MATERIALS AND METHODS: Reported xylem sap proteins curated from Arabidopsis, maize and soybean. Their sequences were put under scrutiny in terms of considering their mobility, and physical and chemical properties. Metabolic energy required for their biosynthesis along with the energy hidden in their peptide bonds were calculated and compared with random non-xylem sap proteins as control. RESULTS: Xylem sap proteins were significantly smaller than the root proteins, while they were bigger in size when compared to the leaf group. Xylem protein pIs were significantly higher than the control proteins in different plants. Similarly, the protein stability was higher for xylem sap proteins in comparison with roots and leaves in all analyzed plants, except for soybean that the stability was indifferent between xylem and root. The data were suggestive a significantly lower energy consumption for the synthesis of xylem sap proteins. CONCLUSIONS: Lower energy consumption may suggest an economical route of communication between roots and shoots in plants that mainly rely on symplastic signaling.

Optimizing micropropagation of drought resistant Pyrus boissieriana Buhse.

The present study concentrated on introducing a micropropagation protocol for a drought resistant genotype from Pyrus boissieriana, which is the second most naturally widespread pear species in Iran with proper physiological and medicinal properties. Proliferating microshoot cultures were obtained by placing nodal segments on MS medium supplemented with BAP and IBA or NAA. The highest number of shoots (27 shoots per explant) were obtained with 1.5 mg l-1 BAP and 0.05 mg l-1 IBA, but this combination did not produce shoots of desirable length (>1.7 cm). Combination of 1.75 mg l-1 BAP and 0.07 mg l-1 IBA was the best for the shoot multiplication in P. boissieriana with a sufficient number of shoot production (22.33 shoots per explant) and relatively more appropriate shoot length. The larger and greenish leaves were obtained when PG was added to the best multiplication treatment. Microshoot elongation was carried out in 1/2 and 1/4 MS medium containing 50-100 mg l-1 PG with different concentrations of IBA or NAA at intervals of 30-60 days. Significant increase in shoot length was detected after 45-60 days of culture in the presence of PG. The highest shoot length (8 cm) was recorded on 1/2 MS medium supplemented with 0.5 mg l-1 IBA and 100 mg l-1 PG. GA3 negatively affected number and length of shoots and generally caused generation of red leaves. The highest percentage of root induction (100%) and root length (9 cm) were obtained on 1/6 strength MS medium supplemented with 0.005 mg l-1 IBA. All plantlets were hardened when transferred to ex vitro conditions through a period of 25-30 days. The results suggest axillary shoot proliferation of P. boissieriana could successfully be employed for propagation of candidate drought resistant seedling.