Plant colonization by pink-pigmented facultative methylotrophic bacteria (PPFMs)

Abstract

Bacteria belonging to the genus Methylobacterium are characterized by being able to rely on methanol as a sole carbon and energy source and by presenting a more or less intense pink reddish pigmentation. These bacteria, also referred to as pink-pigmented methylotrophic bacteria (PPFMs), are common inhabitants of the phyllosphere and are found in many other environmental samples. Since they grow slowly they are often overlooked and their impact on phyllosphere microbial communities and on the plants harboring them is not well studied nor has their ecology been elucidated. In a survey of PPFM colonization in three different agricultural sites, PPFM populations were identified on both red clover and winter wheat, but red clover was more consistently colonized. Isolations from collected leaves showed PPFM populations to decrease from spring towards summer, but they increased again towards the end of the cropping season. Isolates from red clover readily colonized winter wheat leaves and vice versa in greenhouse experiments, but population sizes were dependent on the application procedure. Tested isolates had also good potential to colonize the rhizosphere, especially after seed inoculations. Confocal scanning laser microscopy showed gfp-tagged isolates to colonize the surface of clover leaves by forming large aggregates.

Distribution of Pink-Pigmented Facultative Methylotrophs on Leaves of Vegetables

“…Omer et al (2004) has reported that PPFMs isolated from red clover readily colonized winter wheat leaves and vice versa in greenhouse experiments, and that the tested isolates had good potential to colonize the rhizosphere, especially after seed inoculation. 8) According to Knief et al (2010), factors specific to the sites from which the plant species were collected, more than the plant species themselves, have a strong influence on the composition of the phyllospheric Methylobacterium community. 14) We found that PPFMs were highly abundant on perilla leaves, regardless of the geographic site from which they were collected.…”

“…Makino) leaves (10 5{6 CFU/g of fresh leaves). Although wide distribution and isolation of PPFMs in the phyllosphere has been reported, [5][6][7][8][9][10] PPFMs of green perilla have not been reported previously. The PPFM counts of perilla were higher than those of other taxonomically closely related species such as Plectranthus, belonging to the same family Lamiaceae (Labiatae).…”

Methylotrophic Metabolism Is Advantageous for Methylobacterium extorquens during Colonization of Medicago truncatula under Competitive Conditions

“…Recently published data suggest that the degrees of plant-Methylobacterium association vary from very strong, as exemplified by symbioses, to semitight, as exemplified by endophytic association (7,24,41,56), to loose, as exemplified by epiphytic association on plant surfaces (6,15,40). In the case of symbiosis, the benefit for the plant is evident, in contrast to the looser forms of association between methylotrophs and plants.…”

Bestowing Inducibility on the Cloned Methanol Dehydrogenase Promoter (P mxaF ) of Methylobacterium extorquens by Applying Regulatory Elements of Pseudomonas putida F1

“…Among the methylotrophs, members of the genus Methylobacterium have been described as being ubiquitous, participating in a myriad of favorable interactions with nature (24,26,27). Furthermore, Methylobacterium spp.…”