Multifunctional characteristics of Acinetobacter lwoffii Bac109 for growth promotion and colonization in micropropagated sugarcane

Características multifuncionais de Acinetobacter lwoffii Bac109 para promoção de crescimento e colonização em cana-de-açúcar micropropagada

ABSTRACT

Endophytic bacteria with multifunctional characteristics can benefit plants through different mechanisms, as well as promoting growth in an efficient, low-cost and ecofriendly way. This study analyzed the potential of the multifunctional endophytic isolate Acinetobacter lwoffii Bac109 in promoting the early in vitro growth of sugarcane seedlings. The Bac109 strain showed potential to solubilize phosphate in a solid medium (solubilization index: 3.73). In addition, the bacterium was an efficient biocontrol agent against the phytopathogenic fungi Rhizoctonia sp., Fusarium oxysporum, Phoma sp. and Bipolaris papendorfii, showing a performance equal to or better than the commercial antifungal hygromycin B. An in vitro assay confirmed the biofilm production, which increased in the presence of sugarcane root extract. Additionally, A. lwoffii Bac109 showed a strong adhesion to the sugarcane roots. The inoculation of this bacterium in micropropagated sugarcane seedlings increased the shoot length (35 %) and regulated the nonphotochemical energy dissipation after 28 days of cultivation. At the end of the experiment, the bacterium showed a great potential for survival, with 5.72 × 107 CFU mL^-1 recovered from the substrate, what is crucial for plant interaction. The results showed the potential of the biotechnology application for A. lwoffii Bac109 by evaluating multifunctional traits of plant growth promotion and by specific interactions with sugarcane, which may help to improve micropropagation protocols for this crop.

KEYWORDS:
Saccharum sp; biofilm; biocontrol; cross-inoculation; plant growth promoting bacteria