Diversity and functional characterization of endophyticMethylobacteriumisolated from banana cultivars of South India and its impact on early growth of tissue culture banana plantlets

Abstract

Aims: This study aimed at determining the distribution, colonization and growth promoting nature of Methylobacterium spp. in tissue culture banana plantlets. Methods and Results: Leaf samples from different field grown banana cultivars were used for Methylobacterium spp., isolation. Metabolic profile and functional characterization for plant growth-promoting traits of the isolates were assessed. The isolates were confirmed using 16S rRNA gene sequencing analysis, which resulted in six distinct species of Methylobacterium namely M. radiotolerans, M. salsuginis, M. thiocyanatum, M. rhodesianum, M. rhodinum and M. populi. Methylobacterium spp. inoculation experiment was conducted under hydroponic system in tissue culture banana plantlets (germ free) with eight selected isolates. A significant increase in growth parameters of Methylobacterium treated plantlets compared to uninoculated control was observed. Methylobacterium salsuginis TNMB03-gfp29 was developed and colonization micrograph was obtained using confocal laser scanning microscopy (CLSM) and scanning electron microscopy in different parts of banana plantlets (root, stem and leaves). Conclusion: Field grown banana plants found to harbour diverse endophytic Methylobacterium population. Our finding suggests that endophytic Methylobacterium species may provide significant plant growth promoting compounds/nutrients to the banana plants. The experimental results demonstrated the efficacy of Methylobacterium spp. as a potential bioinoculant and can be exploited as a phyllosphere and rhizosphere based bioinoculant for the initial establishment and growth of tissue culture banana plantlets. Significance and Impact of the Study: This study extended our knowledge on the distribution of Methylobacterium spp. in banana plants and endophytic colonization nature of this particular genus in plants. In addition, efficient isolate (M. salsuginis TNMB03) identified in this study may be promoted as bio-inoculants for banana plants after field evaluation.

Impact of Glyphosate and Glyphosate-Based Herbicides on Phyllospheric Methylobacterium

“…Combined with the results presented herein, the relevant literature supports our theory that GBH's may increase crop susceptibility to infections by selectively attenuating the protective effects of Methylobacteria colonization. This is supported by the fact that, in addition to soybean, the genus of Methylobacteria comprises a major part of the phyllosphere in several of the same food crop systems that exhibit increased susceptibility to infectious disease when exposed to GBH's including: apple [130,131], wheat [61, 132,133], tomato [134,135,136], hemp [137], cotton [138,139], and banana [140,141,142,143]. Importantly, the application of glyphosate has also been previously found to decrease host phytoalexin levels, even when attempting to elicit an immune response through deliberate pathogen challenge [144,145].…”

Methane Oxidation Potentials of Rice-associated Plant Growth Promoting Methylobacterium Species

“…The PCR reaction mixture consisted of a 2 μL template colony mixture, 2 μL of F and R primers each, 10 μL Taq Mix (Dong Sheng Biotech, South Korea) with 2X PCR buffer, 0.4 mM dNTPs, 0.25 U μ L -1 Taq DNA polymerase, and made up to 20 μL using sterile water. The PCR reactions were carried out in a Thermocycler (ThermalCycler, BIO-RAD, USA) with conditions: 95°C for 5 min, 35 cycles consisting of 95°C for 30 sec denaturation, 59°C for 30 sec annealing, and 72°C for 1 min extension with a final extension of 72°C for 15…”

“…Although they can grow on a wide range of multi-carbon substrates, they are known to utilize single carbon compounds such as formate, formaldehyde or methanol, and methylamine [10]. Several Methylobacterial species are plant growth promoting bacteria (PGP) through the production of ACC (1-aminocyclopropane 1-carboxylate) deaminase, indole acetic acid, cytokinin, acids to release insoluble phosphate, siderophore, nitrogen fixation and pathogen antagonism [11][12][13][14][15][16]. Some novel species of Methylobacterium can survive using CH 4 as the sole source of carbon and energy source [17].…”