Acclimatization of Pouteria gardeneriana Radlk micropropagated plantlets: Role of in vitro rooting and plant growth–promoting bacteria

Abstract

Pouteria gardneriana Radlk (guapeva) is a tree native to the Brazilian Cerrado with economic, ecological, and biotechnological importance. Guapeva yield is limited mainly by the seeds recalcitrance, that can be overcome by micropropagation technique and effective acclimatization. The objective of this study was to investigate the role of in vitro rooting and inoculation of plant growth–promoting bacteria (PPGPB) during acclimatization of micropropagated P. gardneriana plantlets. In the first bioassay, the presence of roots in the plantlets resulted in higher values of biometric features, such as leaf area, numbers of leaves and secondary roots, nodal segments, fresh and dry weights of leaves; when compared to plantlets without roots. Roots well established also resulted in higher levels of chlorophyll a, chlorophyll b, and total chlorophyll and a higher photosynthetic rate in micropropagated P. gardneriana plantlets. Fr the second biassay, the PGPB inoculation was done with bacteria to solubilize phosphate and phytohormone production, in addition to low pathogenic potential in the Galeria mellonella larva animal model. The inoculation of the Bac109 and BP323EB consortium in plantlets rooted in vitro had a positive effect on the root length of the plantlets during the acclimatization phase, which may favor the long-term development of the plant. This study demonstrated that both in vitro rooting and inoculation of a bacterial consortium may contribute to the growth of P. gardneriana during acclimatization, leading to higher productivity and seedling quality.