Table 1.
Number of isolates and population densities of diazotrophic/N-scavenging bacteria isolated via different semisolid N-free culture media from soils under different management conditions and from unwashed roots of tomato and lulo plants grown on those soils.
Fig 1.
Qualitative and quantitative distribution of bacterial strains isolated from different sources and from soils under different management conditions according to phylogenetic positioning at the genus level (1A), relative abundance (1B) and isolation source (1C). The chart legend indicates the identified genus and respective classes. BS, soil; TR, tomato unwashed roots; LR, lulo unwashed roots; SF, secondary forest soil with no agricultural use; CH, horticulture soil under conventional management; ORG, horticulture soil under organic management.
Fig 2.
Dendrogram representing the genotype diversity and genetic relationships estimated by the cluster analysis of BOX-PCR fingerprints of diazotrophic/N-scavenging bacteria isolated from different sources and from soils under different management conditions.
Dendogram was constructed using the Jaccard coefficient (2% tolerance in terms of band size) with the UPGMA algorithm. Isolation sources: BS (soil); LR (lulo unwashed roots), TR (tomato unwashed roots). Soil management conditions: CH (horticulture under conventional management); ORG (horticulture under organic management); SF (secondary forest with no agricultural use).
Fig 3.
Qualitative representation of plant growth-promoting traits observed for diazotrophic/N-scavenging bacteria isolated from different sources and from soils under different management conditions.
(A) Venn diagram showing unique and shared plant growth-promoting (PGP) traits detected for the bacterial strains studied. (B) Quantitative distribution of bacterial strains according to isolation source and PGP traits. (C) Quantitative distribution of bacterial strains according to phylogenetic position at the genus level and PGP traits.
Fig 4.
Accumulation of biomass of the root system or aerial tissues of lulo and tomato plants grown under N-limiting conditions in response to the inoculation of 101 different diazotrophic/N-scavenging bacteria.
(A, C) Root dry weight (g plant-1) of tomato (S. lycopersicum) and lulo (S. quitoense) plants, respectively. (B, D) Shoot dry weight (g plant-1) of tomato (S. lycopersicum) and lulo (S. quitoense) plants, respectively. The mean values plotted in the same color represent groups that do not significantly differ at p < 0.05 according to the Scott-Knott algorithm. The bars refer to the maximum and minimum values for each plot. RDW, root dry weight; SDW, shoot dry weight.
Table 2.
Rank position and arbitrary values converted from the percentage (%) between the absolute value and the mean trait value (in vitro and in vivo determinations) for diazotroph/N scavenger bacterial strains considered to have high biotechnological potential to promote the growth of Solanum (rank greater than or equal to 10) according to the bonitur scale.