Pectin-Rich Amendment Enhances Soybean Growth Promotion and Nodulation Mediated by Bacillus Velezensis Strains

Abstract

Plant growth-promoting rhizobacteria (PGPR) are increasingly used in crops worldwide. While selected PGPR strains can reproducibly promote plant growth under controlled greenhouse conditions, their efficacy in the field is often more variable. Our overall aim was to determine if pectin or orange peel (OP) amendments to Bacillus velezensis (Bv) PGPR strains could increase soybean growth and nodulation by Bradyrhizobium japonicum in greenhouse and field experiments to reduce variability. The treatments included untreated soybean seeds planted in field soil that contained Bv PGPR strains and non-inoculated controls with and without 0.1% (w/v) pectin or (1 or 10 mg/200 μL) orange peel (OP) amendment. In greenhouse and field tests, 35 and 55 days after planting (DAP), the plants were removed from pots, washed, and analyzed for treatment effects. In greenhouse trials, the rhizobial inoculant was not added with Bv strains and pectin or OP amendment, but in the field trial, a commercial B. japonicum inoculant was used with Bv strains and pectin amendment. In the greenhouse tests, soybean seeds inoculated with Bv AP193 and pectin had significantly increased soybean shoot length, dry weight, and nodulation by indigenous Bradyrhizobium compared to AP193 without pectin. In the field trial, pectin with Bv AP193 significantly increased the shoot length, dry weight, and nodulation of a commercial Bradyrhizobium japonicum compared to Bv AP193 without pectin. In greenhouse tests, OP amendment with AP193 at 10 mg significantly increased the dry weight of shoots and roots compared to AP193 without OP amendment. The results demonstrate that pectin-rich amendments can enhance Bv-mediated soybean growth promotion and nodulation by indigenous and inoculated B. japonicum.

Plant Growth Promotion Abilities of Phylogenetically Diverse Mesorhizobium Strains: Effect in the Root Colonization and Development of Tomato Seedlings

“…The plant growth promoting rhizobacteria (PGPR), also named plant probiotic bacteria, are promising biofertilizers for sustainable and environmentally friendly agriculture since they allow the total or partial substitution of chemical fertilizers added to the crops alone or together with organic amendments [1][2][3]. These bacteria take part in the plant microbiome and can live in the rhizosphere or endosphere of plants [4,5].…”

Sustaining the growth of Pinaceae trees under nutrient-limited edaphic conditions via plant-beneficial bacteria

“…Plant-growth-promoting bacteria have been studied widely in agricultural and horticultural crops for decades [13][14][15][16] and several agro-tech companies have made PGPB inoculants commercially available for farmers as an alternative to chemical fertilizers and pesticides [17,18]. However, the use of such inoculants in natural boreal and temperate forest stands to promote regeneration of coniferous trees is less common, primarily because the association of conifers with PGPB and the underlying mechanisms of tree growth promotion are understudied [19].…”

Plant Polysaccharides Modulate Biofilm Formation and Insecticidal Activities of Bacillus thuringiensis Strains

“…Pectin-rich amendment enhances soybean growth promotion and modulation mediated by Bacillus velezensis ( Hassan et al, 2019 ). In this study, pectin can promote the biocontrol activities of biofilms formed by the logarithmic growth phase or lysis phase of Bt cells.…”