Abstract
A number of pink-pigmented facultative methylotrophs (PPFMs) belonging to Methylobacterium spp. isolated from living plant samples were found to require B vitamins for their growth in minimal medium, and most B vitamin-auxotrophic PPFMs required pantothenate (vitamin B5). Further investigation of pantothenate auxotrophy using the representative strain Methylobacterium sp. OR01 demonstrated that this strain cannot synthesize β-alanine, one of the precursors of pantothenate. β-alanine and several precursors of pantothenate restored the growth of Methylobacterium sp. OR01 in minimal medium. Furthermore, this strain could colonize leaves of Arabidopsis thaliana cultivated in medium without pantothenate or its precursors. Pantothenate, β-alanine and several precursors were detected in the suspension of A. thaliana leaves. These results suggest that pantothenate-auxotrophic PPFMs can symbiotically colonize the surface of plant leaves by acquiring β-alanine and other precursors, in addition to pantothenate. Finally, the fitness advantage of B vitamin auxotrophy of PPFMs in the phyllosphere environment is discussed.
Highlights
These results suggest that pantothenate-auxotrophic pink-pigmented facultative methylotrophs (PPFMs) can symbiotically colonize the surface of plant leaves by acquiring β-alanine and other precursors, in addition to pantothenate
We found that many PPFMs isolated from living plant samples exhibit B-vitamin auxotrophy, especially pantothenate auxotrophy, and the representative Methylobacterium sp
Pantothenate auxotrophy of PPFMs isolated from living plant samples
Summary
Methylobacterium sp. strain was used for comparison (Table 1). leaves inoculated with Methylobacterium sp. Was shown to utilize pantothenate or its precursors from the leaf surface environment of Arabidopsis (Figure 4(a) and Table 2). OR01 could colonize Arabidopsis leaves cultivated on plant medium which did not contain pantothenate or its precursors (Figure 4(a)) and that pantothenate, β-alanine, and several precursor compounds were present on Arabidopsis leaves (Table 2). 100-fold higher than that of pantothenate and other precursors (Table 2) and that the minimum concentrations of pantothenate and β-alanine necessary to support the growth of Methylobacterium sp. OR01, which is a dominant colonizer on plant leaves and can be directly transmitted from seeds to leaves [25], might have increased fitness by acquiring pantothenate and β-alanine, which are present in the phyllosphere, saving energy costs for biosynthesis of these compounds, and by possessing multiple pathways for β-alanine biosynthesis from several precursors available in the phyllosphere.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
