Understanding a relationship between microbiomes and plant diseases: evaluation of the effect of Asian Soybean Rust on leaf bacterial community

Abstract

Like animals, plants harbor complex microbial communities on the surface and inside of their tissues. Many of these microorganisms can bring benefits to the host plant, even contributing to the protection against pathogens. The plant microbiome is an emerging field of study and forms an important frontier in our knowledge of interactions between plants and microorganisms. Notably, little is yet known about how the microbiome interacts with the plant immune system or with phytopathogenic microorganisms. The study of plant microbiomes is in evidence because it is believed that in-depth knowledge and manipulation of the plant-associated microbial community, especially those of commercial interest, may offer possibilities for improving agronomic characteristics in crops. Among these characteristics, resistance to pathogens is of great relevance to agriculture. Soybean is the most important crop in Brazil, but its production is severely damaged by Asian Soybean Rust disease, caused by the fungus Phakopsora pachyrhizi. The present proposal aims to investigate how ASR disease affects soybean leaf microbiome. This will be accomplished through high-throughput sequencing of the 16S rRNA gene from bacterial communities that colonize healthy and infected soybean leaves. We hope that the infection will alter the niche found in the leaves of the plant and thus result in the selection of a different bacterial community from that found in healthy plants. We hypothesized that bacteria more efficient in competing with P. pachyrhizi fungus present greater abundance in infected plants. Thus, a collection of "soy-associated bacteria" will be constructed by isolating leaf bacteria from healthy plants and those with varying levels of disease severity. This collection will be used in a large-scale screening to find strains that may mitigate ASR development in soybean leaves. These efforts will expand our understanding of the effect of disease on plant microbiomes and may support the future development of effective biofungicides against one of Brazil's most important plant diseases. (AU)