Characterization of Bacterial Isolates for Sustainable Rice Blast Control

Abstract

Rice blast (Magnaporthe oryzae) limits rice (Oryza sativa) grain yields worldwide. The objective of this investigation was to morphologically, biochemically, and molecularly characterize six bacterial isolates, BRM 32109, BRM 32110, BRM 32111, BRM 32112, BRM 32113, and BRM 32114, and to determine their potential as antagonists to M. oryzae. Morphological characterization was based on colony formation and color, Gram staining, and fluorescent pigment production. Biochemical studies were based on cellulase, chitinase, phosphatase, indoleacetic acid, and siderophore production, as well as biofilm formation. The molecular identification used specific primers for PCR amplification of the 16S rRNA region, followed by sequencing. The antagonism studies involved three experiments, which had randomized designs. Two of them were conducted in laboratory conditions, pairing bacterial colonies and M. oryzae, using bacterial filtrates, and the third was conducted in greenhouse conditions. BRM 32111 and BRM 32112 were identified as Pseudomonas sp., BRM 32113 as Burkholderia sp., BRM 32114 as Serratia sp., and BRM 32110 and BRM 32109 as Bacillus spp. BRM 32112, BRM 32111, and BRM 32113 inhibited the colony of M. oryzae by 68%, 65%, and 48%, respectively. The bacterial suspensions of the BRM 32111, BRM 32112, and BRM 3212 filtrates suppressed leaf blast by 81.0, 79.2, and 66.3%, respectively. BRM 32111 and BRM 32112 were determined to be antagonists of M. oryzae and were found to solubilize phosphate, produce siderophores and cellulose, form biofilms, and suppress leaf blast. These isolates should be further investigated as potential biological control agents for leaf blast control.

Optimization of the Extraction Process and Application of Bacterial Extracts in the Control of Brown Spot and Leaf Blast in Rice Culture

“…The Bacillus sp. BRM 32110 and S. marcescens BRM32113 species under study, were isolated from the rhizosphere of upland rice by Filippi et al (2011), who performed the phenotypic, biochemical and molecular characterization, through the ampli cation of the gene encoding the 16S rRNA region (Martins et al 2020). Other works of the same research group revealed that these same isolates are growth promoters in rice, soybean and bean crops, antagonists to some phytopathogens such as M. oryzae and B. oryzae and resistance inducers.…”

“…The bacterial isolate BRM32113 was initially identi ed by Martins et al (2020), as Burkholderia pyrrocinia, analyzing the sequencing obtained from the ampli cation of the 16S rRNA gene, and the biochemical and morphological identi cation. But the analysis of the 16S rRNA gene extract from the complete genome sequencing of isolate BRM 32113 revealed that it is from the genus Serratia and species marcescens.…”

“…Among them we highlight those of the genus Bacillus and Serratia. (Filippi et al 2011;Martins 2015;Martins et al 2020). Bacteria of the genus Bacillus belong to the phylum Firmicutes, family Bacillaceae, can be found in soil, in association with plants, rivers, and estuaries and produce several metabolites of industrial interest such as enzymes, B-exotoxin, thuricin, petrobactim, bacillibactim (Bach et al 2011;Sansinenea et al 2011).…”

Desempenho Dos Métodos De Estimação Genômicos Na Identificação Da Resistência Do Arroz À Brusone

“…Mundialmente, o aumento da demanda por arroz se dá em função do crescimento constante da população. O consumo per capita global deste alimento é estimado em cerca de 57 kg/ano (NASCENTE et al, 2019) e estima-se que a demanda de arroz passará de 496 milhões de toneladas em 2020 para 555 milhões de toneladas em 2035 (MARTINS et al, 2020).…”

“…Dentre os estresses bióticos mais comuns que infectam a cultura de arroz, destaca-se a brusone. Causada por um fungo hemibiotrófico (Magnaporthe oryzae), a doença pode resultar em perdas de 100% em cultivares de arroz suscetíveis, limitando sua produtividade (MARTINS et al, 2020). De acordo com Jiang et al 2020, nas áreas tropicais e temperadas do planeta a brusone é avaliada como uma das doenças mais graves do arroz.…”