| Congresso Brasileiro de Microbiologia 2023 | Resumo: 297-1 | ||||
Resumo:Rice (Oryza sativa L.) is a highly relevant cereal to Brazilian culture and has great economic
relevance, with approximately 2 million tons exported in 2022. Rice crops are usually cultivated
in upland or lowland systems, the latter representing more than 85% of Brazil’s total rice
production. Like other crops, rice is susceptible to phytopathologies during all its development,
with rice blast disease being one of the main causes of economic losses to farmers. This disease
is caused by the fungus Pyricularia oryzae (PO), which can infect different organs of the plant
(nodes, leaves, seeds, and panicles), block the transport of sap in the plant’s vessels and lead to
total loss of the crop. The main control employed for rice blast disease is the use of chemical
agents that, after numerous applications in rice crops, facilitate the selection of resistance genes
in PO. Currently, there is no rice cultivar totally resistant to blast disease, but the usage of
biological control agents, such as plant growth-promoting bacteria (PGPB), has been shown to
be a key alternative to control the spread of the disease. In a previous study developed by our
group, strains of Paenibacillus brasilensis (PB) isolated from different kinds of soil showed
nitrogen fixating capacities and antimicrobial substance production, making them potential
candidates for the biocontrol of PO. To explore the antifungal action against PO and the plant
growth-promoting potential that PB presents in vitro, to offer other alternatives to farmers for the
control of rice blast disease and to increase rice crop productivity, this study aims to 1) perform in
vitro antagonism tests between PB and PO strains; 2) analyze the potential of PB strains to
promote rice growth; and 3) analyze the capacity of PB strains to inhibit and/or reduce rice blast
disease development in vivo. For the in vitro antagonism tests, three PB strains were used, PB24,
PB177, and SA3, and showed positive results by inhibiting PO growth. Thereafter, plant growth
promotion tests were performed on rice seeds using the three PB strains. For each of the three
strains, germination chamber assays were conducted using 2 treatments (n=9 for each): T1 -
seeds inoculated with the PB strains and T2 - seeds inoculated with 0.85% saline solution
(control). In this assay, the germination rate was higher in the PB24 (77.8%) and PB177 (88.9%)
treatments than in the control (66.7%). In the next assay, we will inoculate both PB and PO strains
in rice seeds to analyze PB’s performance against PO in vivo and rice blast disease symptoms
and plant development (aerial, roots and plant biomass) will be analyzed, along with the
evaluation of the treatment impact on the rice microbiome through 16S and 18S gene
metabarcoding. In the future, we intend to develop a microbial inoculant with PB to offer effective
alternatives to the biocontrol of rice blast disease. Palavras-chave: Paenibacillus brasilensis, rice blast disease, Pyricularia oryzae, biological control, Oryza sativa L Agência de fomento:CNPq, FAPERJ, CAPES and EMBRAPA | |||||