AUTHOR=Mohanty Santosh Ranjan , Mahawar Himanshu , Bajpai Apekcha , Dubey Garima , Parmar Rakesh , Atoliya Nagvanti , Devi Mayanglambam Homeshwari , Singh Amar Bahadur , Jain Devendra , Patra Ashok , Kollah Bharati 

TITLE=Methylotroph bacteria and cellular metabolite carotenoid alleviate ultraviolet radiation-driven abiotic stress in plants

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.899268

DOI=10.3389/fmicb.2022.899268

ISSN=1664-302X

ABSTRACT=<p>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 <italic>Methylobacteria</italic> 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 (o<italic>ryzae sativa</italic>). The 16S <italic>rRNA</italic> gene sequence of the bacterium was homologous to the <italic>Methylobacter sp</italic>. The isolate referred to as <italic>Methylobacter sp</italic> N39, produced beta-carotene at a rate (μg ml<sup>–1</sup> d<sup>–1</sup>) 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 <italic>y</italic> = 3.09 × incubation period + 22.151 (<italic>r</italic><sup>2</sup> = 0.90). The carotenoid extract of N39 protected <italic>E. coli</italic> from UV radiation by declining its death rate from 14.67% min<sup>–1</sup> to 4.30% min<sup>–1</sup> under UV radiation. Application of N39 cells and carotenoid extract also protected <italic>rhizobium</italic> (<italic>Bradyrhizobium japonicum</italic>) cells from UV radiation. Scanning electron microscopy indicated that the carotenoid extracts protected <italic>E. coli</italic> 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 <italic>Methylobacter sp</italic> N39 and its carotenoid extract can be explored to manage UV radiation stress in agriculture.</p>