Effect of Pseudomonas protegens EMM-1 Against Rhizopus oryzae in Interactions with Mexican Autochthonous Red Maize

In the present study, the strain <i>Rhizopus oryzae</i> EMM was isolated from germinated autochthonous red maize seeds, which were harvested in a region of San Diego-Buenavista, Papalotla, Tlaxcala, Mexico, where cobs with fungal infections have been observed. This fungal strain caused wilting in the maize seedlings. <i>Pseudomonas protegens</i> EMM-1 was tested for its ability to inhibit <i>R. oryzae</i> EMM, both in culture media and in association with maize plantlets. <i>P. protegens</i> EMM-1 inhibited the growth of <i>R. oryzae</i> EMM under all culture media conditions explored. The ability of <i>P. protegens</i> EMM-1 to inhibit the growth of <i>R. oryzae</i> EMM associated with plants was evaluated in both a hydroponic system and in vermiculite. In both systems, <i>P. protegens</i> EMM-1 strongly inhibited the growth of <i>R. oryzae</i> EMM. The dry weight of root plants infected with <i>R. oryzae</i> EMM and inoculated with <i>P. protegens</i> EMM-1 increased to 0.43 g, while that of plants infected only with <i>R. oryzae</i> EMM reached just 0.19 g under hydroponic conditions. However, no differences were observed under vermiculite conditions. The dry weight of the aerial region of plants infected with <i>R. oryzae</i> EMM and inoculated with <i>P. protegens</i> EMM-1 was greater than that of plants infected only with <i>R. oryzae</i> EMM, both under hydroponic and vermiculite conditions. These results indicate that <i>P. protegens</i> EMM-1 inhibits the infection caused by <i>R. oryzae</i> EMM, thereby improving plant growth. Moreover, the genome analysis of <i>P. protegens</i> EMM-1 revealed the presence of several genes that potentially encode for antimicrobial compounds, which could strengthen the potential use of <i>P. protegens</i> EMM-1 as a biocontrol agent in maize plants.