Abstract
Endophytes are usually protected from soil environment competitiveness and stress. However, the presence of heavy metals can negatively affect the structure and diversity of endophyte communities. The aim of the present study was evaluate the diversity of endophytic bacteria from ipe mirim (Tecoma stans Bignoniaceae) grown in an area of Atlantic rainforest contaminated with metals and evaluate the ability of these bacteria to promote plant growth and seed germination. Results show that endophytic bacterial density in plants was stable among sites with different level of metals; however, bacterial richness was lower in plants from sites with low level of metals. At least 28 genera were isolated, where Methylobacterium (21.32%), Bacillus (19.12%), Pseudomonas (11.03%) and Curtobacterium (7.35%) the dominant groups. Isolates were selected from Rhizobiales order and the capability of this dominant group in plant growth promotion was evaluated. Results showed that Methylobacterium spp. and Rhizobium sp. increased germination and improved seedling growth of tomato Santa Cruz Kada Gigante. Therefore, results show that the endophyte cultivable community is not influenced by the presence of low metal concentration, and plant growth promoter bacteria that can be used on tomato seedlings production were successfully selected and on future phytoremediation studies. Key words: Methylobacterium spp., Rhizobium sp., Tecoma stans, microbial diversity, metals, plant growth promoting bacteria (PGPB), tomato, growth promotion.
Highlights
The endophytic bacteria colonize the inner plant tissues without causing disease and without visible external structures (Hardoim et al, 2008, 2015)
The aim of the present study was evaluate the diversity of endophytic bacteria from ipê mirim (Tecoma stans Bignoniaceae) grown in an area of Atlantic rainforest contaminated with metals and evaluate the ability of these bacteria to promote plant growth and seed germination
Results show that endophytic bacterial density in plants was stable among sites with different level of metals; bacterial richness was lower in plants from sites with low level of metals
Summary
The endophytic bacteria colonize the inner plant tissues without causing disease and without visible external structures (Hardoim et al, 2008, 2015). This relationship can be beneficial for both plant and microorganisms; studies. The diversity of endophytic bacteria may be impacted by biotic (plant genotypes and microbial community) and abiotic (nutrients, water, temperature, pH and pollutants) factors (Hardoim et al, 2008). Endophytes are protected of stress and competitiveness from soil environment (Gans et al, 2005), the presence of heavy metals may negatively affect the structure and diversity of microbial communities. It is important to understand the factors that affect the endophytic community and its impact on the biotechnological potential of this community
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