Beneficial bacteria improve seedling growth and nutrition and promote biological control of coffee diseases

Abstract

Aim: We investigated the effects of plant growth-promoting bacteria (PGPB) on the growth and nutrition of coffee seedlings and the biological control of coffee leaf rust (Hemileia vastatrix), brown eye spot (Cercospora coffeicola), and leaf blight (Boeremia coffeae). Methods and results: In the first part of the study, 19 PGPB strains, obtained in the phyllosphere, endosphere, and rhizosphere of coffee and other hosts, produced varied metabolites related to plant growth and biological control. Two coffee cultivars were treated with the bacterial strains, but cultivar Catuaí Amarelo IAC 62 was less responsive to the treatments. Five rhizospheric strains, from different genera, Bacillus cereus (Rb1), Pseudomonas koreensis (Rb2b), Enterobacter mori (Mn2), Bacillus safensis (Ob3a), Enterobacter cloacae (RBca5), and two endophytic strains, Enterobacter hormaechei (EOb1) and Paraburkholderia caribensis (Beca88) enhanced seed germination, plant biomass, and nutrient accumulation in cultivar Catuaí VermelhoIAC144 seedlings. In the second part of the study, three strains, the phyllospheric Pseudomonas gozinkensis (Mn1F), the endophytic P. caribensis (BEca88), and the rhizospheric E. cloacae (RBca5) reduced the severity of coffee leaf rust, brown eye spot, and leaf blight. Conclusions: PGPB from different genera, obtained in varied hosts and habitats, showed positive effect, improving plant fitness and controlling important coffee diseases, standing out the strains P. gozinkensis (Mn1F), P. caribensis (IAC-BEca-088), and E. cloacae (IAC-RBca5).