Seed Endophyte Microbiome of Crotalaria pumila Unpeeled: Identification of Plant-Beneficial Methylobacteria

Abstract

Metal contaminated soils are increasing worldwide. Metal-tolerant plants growing on metalliferous soils are fascinating genetic and microbial resources. Seeds can vertically transmit endophytic microorganisms that can assist next generations to cope with environmental stresses, through yet poorly understood mechanisms. The aims of this study were to identify the core seed endophyte microbiome of the pioneer metallophyte Crotalaria pumila throughout three generations, and to better understand the plant colonisation of the seed endophyte Methylobacterium sp. Cp3. Strain Cp3 was detected in C. pumila seeds across three successive generations and showed the most dominant community member. When inoculated in the soil at the time of flowering, strain Cp3 migrated from soil to seeds. Using confocal microscopy, Cp3-mCherry was demonstrated to colonise the root cortex cells and xylem vessels of the stem under metal stress. Moreover, strain Cp3 showed genetic and in planta potential to promote seed germination and seedling development. We revealed, for the first time, that the seed microbiome of a pioneer plant growing in its natural environment, and the colonisation behaviour of an important plant growth promoting systemic seed endophyte. Future characterization of seed microbiota will lead to a better understanding of their functional contribution and the potential use for seed-fortification applications.

Responses of the Endophytic Bacterial Communities of Juncus acutus to Pollution With Metals, Emerging Organic Pollutants and to Bioaugmentation With Indigenous Strains

“…Strains were tagged with fluorescent proteins as previously described ( Sánchez-López et al, 2018 ) in order to monitor their colonization to the host plant under similar experimental conditions. The labeled strains were inoculated (10 9 cells mL -1 ) to plants with and without addition of pollutants.…”

“…The labeled strains were inoculated (10 9 cells mL -1 ) to plants with and without addition of pollutants. Their colonization efficiency was investigated with a confocal laser microscope Ultra VIEW VoX, PerkinElmer (Zaventem, Belgium) using an excitation wavelength of 561 nm (red) for mCherry, and 405 (Dapi) for plant cell walls while the confocal pictures were analyzed using ImageJ software and Amira 3D visualization software version 6.1.0 (FEI Visualization Sciences Group, Hillsboro, OR, United States) as previously described ( Sánchez-López et al, 2018 ).…”

Core Microbiome of Medicinal Plant Salvia miltiorrhiza Seed: A Rich Reservoir of Beneficial Microbes for Secondary Metabolism?

“…Some studies have shown that seed core microbiome is specific for terroir and emergence [ 15 , 16 ]. Seed microbiomes have diverse seed–microbe interactions, and properties, such as being fast-growing, use as bio-fertilizer, antagonistic properties, and ability to cope with environmental stress [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ], and are predicted to be an important biological resource for sustainable agriculture [ 24 ].…”

Differential niche occupation and the biotechnological potential of Methylobacterium species associated with sugarcane plants

“…authors described that the association must be a very specific and strong plant microbe interaction, considering that the plant exudes specific toxic methylated compounds such as pyrrolizidine alkaloids (Wink and Mohamed, 2003) to select specific and high specialized microbes, in order to prompt the plant development (Sánchez-López et al, 2018). Therefore, the plant"s selection of crucial symbiotic microorganisms is based on the methylotrophic abilities of the Methylobacterium spp., which might detoxify these compounds and use them as a source of nutrients (Sy et al, 2001).…”