The modulation of sugarcane growth and nutritional profile under aluminum stress is dependent on beneficial endophytic bacteria and plantlet origin

Plant growth-promoting bacteria (PGPB) are claimed to not only improve plant fitness but also alleviate plant stress. In this study, we evaluated the effect of five PGPB strains on plantlet growth and nutrient and aluminum (Al) uptake under acid soil conditions characterized by low P and K nutrient availability and high metal and aluminum (Al) bioavailability, which may represent a stress condition for crop plants. The PGPB strains were inoculated in sugarcane plantlets produced by meristem tissue culture (MCPs) or one-bud stalks (O-BSPs) and cultivated in soil at 37% Al saturation and pH 4.0. Biomass accumulation and Al and nutrient content in roots and shoots were determined after 30 days of growth. Bacterial inoculation increased root and shoot biomass. However, the magnitudes of these increases were dependent on bacterial strain and plantlet origin. The inoculated plantlets exhibited increased Al content and shifts in Al allocation and calcium (Ca) and boron (B) content among different plant parts (root or shoot), and these changes also depended on plantlet origin and the inoculated strain. The higher Ca uptake of inoculated MCPs and higher B uptake of inoculated O-BSPs may have contributed to reducing the damage caused by excessive Al content. The beneficial microbes also caused changes in plant uptake of micronutrients and slightly reduced macronutrient content. Pseudomonas fluorescens (IAC/BECa 141), Kosakonia radicincitans (IAC/BECa 95), Paraburkholderia tropica (IAC/BECa 135) and Herbaspirillum frisingense (IAC/BECa 152) showed potential for alleviating Al stress in sugarcane plantlets.