Increasing UV radiation in the atmosphere due to the depletion of ozone layer is emerging abiotic stress for agriculture. Although plants have evolved to adapt to UV radiation through different mechanisms, but the role of phyllosphere microorganisms in counteracting UV radiation is not well studied. The current experiment was undertaken to evaluate the role of phyllosphere Methylobacteria and its metabolite in the alleviation of abiotic stress rendered by ultraviolet (UV) radiation. A potential pink pigmenting methylotroph bacterium was isolated from the phylloplane of the rice plant (oryzae sativa). The 16S rRNA gene sequence of the bacterium was homologous to the Methylobacter sp. The isolate referred to as Methylobacter sp N39, produced beta-carotene at a rate (μg ml^–1 d^–1) of 0.45–3.09. Biosynthesis of beta-carotene was stimulated by brief exposure to UV for 10 min per 2 days. Carotenoid biosynthesis was predicted as y = 3.09 × incubation period + 22.151 (r² = 0.90). The carotenoid extract of N39 protected E. coli from UV radiation by declining its death rate from 14.67% min^–1 to 4.30% min^–1 under UV radiation. Application of N39 cells and carotenoid extract also protected rhizobium (Bradyrhizobium japonicum) cells from UV radiation. Scanning electron microscopy indicated that the carotenoid extracts protected E. coli cells from UV radiation. Foliar application of either N39 cells or carotenoid extract enhanced the plant’s (Pigeon pea) resistance to UV irradiation. This study highlight that Methylobacter sp N39 and its carotenoid extract can be explored to manage UV radiation stress in agriculture.

Experiments were carried out to elucidate linkage between methane consumption and mineralization of phosphorous (P) from different P sources. The treatments were (i) no CH₄ + no P amendment (absolute control), (ii) with CH₄ + no P amendment (control), (iii) with CH₄ + inorganic P as Ca₃(PO₄)₂, and (iv) with CH₄ + organic P as sodium phytate. P sources were added at 25 µg P·(g soil)⁻¹. Soils were incubated to undergo three repeated CH₄ feeding cycles, referred to as feeding cycle I, feeding cycle II, and feeding cycle III. CH₄ consumption rate k (µg CH₄ consumed·(g soil)⁻¹·day⁻¹) was 0.297 ± 0.028 in no P amendment control, 0.457 ± 0.016 in Ca₃(PO₄)₂, and 0.627 ± 0.013 in sodium phytate. Rate k was stimulated by 2 to 6 times over CH₄ feeding cycles and followed the trend of sodium phytate > Ca₃(PO₄)₂ > no P amendment control. CH₄ consumption stimulated P solubilization from Ca₃(PO₄)₂ by a factor of 2.86. Acid phosphatase (µg paranitrophenol released·(g soil)⁻¹·h⁻¹) was higher in sodium phytate than the no P amendment control. Abundance of 16S rRNA and pmoA genes increased with CH₄ consumption rates. The results of the study suggested that CH₄ consumption drives mineralization of unavailable inorganic and organic P sources in the soil ecosystem.

Background: Both endophytes, microorganisms that reside within plants, and methylotrophs, which grow using methanol produced from plant leaves, play key roles in protecting plants against biotic and abiotic stresses. However, the source of endophytes and the mechanisms of their selection in plants are poorly understood. Therefore, experiments were carried out to identify wheat seed methylotrophic endophytes and evaluate their partitioning in root, stem and leaf of aseptic-controlled plants cultivated from surface-sterilized seeds. Results: The counts of endophytic methanol utilizers were higher in leaf tissue than in stem, root and seed, as estimated using viable counts and qPCR targeting rrn gene. The methanol dehydrogenase subunit mxaF gene was PCR-detected in all pink-coloured isolates that grew using methanol or succinate. These pink-pigmented facultative methylotrophs (PPFM) were dominant in shoot tissue. Using mass spectrometry for alkaloid content analysis, peganine was detected as a peak 16.6% higher in root than shoot. Root extracts and peganine alone inhibited the growth of PPFM. Conclusions: PPFM transmitted from seed are more abundant in shoot than root. How plant compounds such as peganine are involved in the methylotrophic endo-phytomicrobiome dynamics remains to be better characterized.

Crop residue incorporation to the soil is an essential strategy to improve soil quality and crop productivity in order to attain sustainable development goals. Experiments were conducted to evaluate the differential effect of crop residues on CH₄production and consumption in a tropical vertisol. Soils were incubated with residues of cereals (maize and wheat) and legumes (chickpea and soybean) at 1% w/w, under non-flooded and flooded conditions to estimate CH₄consumption and CH₄production rates, respectively. Rates of CH₄production (ng CH₄produced g/soil/day) varied from 0.068 to 0.107 with lowest in chickpea residue and highest in wheat straw amended soil. CH₄consumption rates (ng CH₄consumed g/soil/day) was highest (0.79) in wheat straw amended soil and lowest (0.53) in chickpea residue amended soil. Organic carbon (%) and available NO₃⁻(mM) contents increased significantly (P> 0.05) in residue amended soils over control under both flooded (methanogenic) and non-flooded (methane consuming) conditions. Abundance of methanogens and methanotrophs was estimated as mcr and pmoA gene copies g⁻¹soil, indicated that both the microbial groups were stimulated significantly due to the amendment of crop residues. Linear models exhibited significant correlation among CH₄production and consumption with organic carbon, available nitrate and microbial abundance. The study highlights that crop residues incorporation influences both CH₄consumption and production potential of soil and this effect is more pronounced with biomass of cereals than legumes.