Biocontrol and plant growth promoting traits of two avocado rhizobacteria are orchestrated by the emission of diffusible and volatile compounds
Por:
Cortazar-Murillo, Elvis M., Mendez-Bravo, Alfonso, Monribot-Villanueva, Juan L., Garay-Serrano, Edith, Kiel-Martinez, Ana L., Ramirez-Vazquez, Monica, Guevara-Avendano, Edgar, Mendez-Bravo, Alejandro, Guerrero-Analco, Jose A., Reverchon, Frederique
Publicada:
3 may 2023
Resumen:
Avocado (Persea americana Mill.) is a tree crop of great social and
economic importance. However, the crop productivity is hindered by
fast-spreading diseases, which calls for the search of new biocontrol
alternatives to mitigate the impact of avocado phytopathogens. Our
objectives were to evaluate the antimicrobial activity of diffusible and
volatile organic compounds (VOCs) produced by two avocado rhizobacteria
(Bacillus A8a and HA) against phytopathogens Fusarium solani, Fusarium
kuroshium, and Phytophthora cinnamomi, and assess their plant growth
promoting effect in Arabidopsis thaliana. We found that, in vitro, VOCs
emitted by both bacterial strains inhibited mycelial growth of the
tested pathogens by at least 20%. Identification of bacterial VOCs by
gas chromatography coupled to mass spectrometry (GC-MS) showed a
predominance of ketones, alcohols and nitrogenous compounds, previously
reported for their antimicrobial activity. Bacterial organic extracts
obtained with ethyl acetate significantly reduced mycelial growth of F.
solani, F. kuroshium, and P. cinnamomi, the highest inhibition being
displayed by those from strain A8a (32, 77, and 100% inhibition,
respectively). Tentative identifications carried out by liquid
chromatography coupled to accurate mass spectrometry of diffusible
metabolites in the bacterial extracts, evidenced the presence of some
polyketides such as macrolactins and difficidin, hybrid peptides
including bacillaene, and non-ribosomal peptides such as bacilysin,
which have also been described in Bacillus spp. for antimicrobial
activities. The plant growth regulator indole-3-acetic acid was also
identified in the bacterial extracts. In vitro assays showed that VOCs
from strain HA and diffusible compounds from strain A8a modified root
development and increased fresh weight of A. thaliana. These compounds
differentially activated several hormonal signaling pathways involved in
development and defense responses in A. thaliana, such as auxin,
jasmonic acid (JA) and salicylic acid (SA); genetic analyses suggested
that developmental stimulation of the root system architecture by strain
A8a was mediated by the auxin signaling pathway. Furthermore, both
strains were able to enhance plant growth and decreased the symptoms of
Fusarium wilt in A. thaliana when soil-inoculated. Collectively, our
results evidence the potential of these two rhizobacterial strains and
their metabolites as biocontrol agents of avocado pathogens and as
biofertilizers.
Filiaciones:
Cortazar-Murillo, Elvis M.:
Inst Ecol AC, Red Estudios Mol Avanzados, Xalapa, Veracruz, Mexico
Mendez-Bravo, Alfonso:
Univ Nacl Autonoma Mexico, CONACyT Escuela Nacl Estudios Super, Unidad Morelia, Lab Nacl Anal & Sintesis Ecol, Morelia, Michoacan, Mexico
Monribot-Villanueva, Juan L.:
Inst Ecol AC, Red Estudios Mol Avanzados, Xalapa, Veracruz, Mexico
Garay-Serrano, Edith:
Inst Ecol AC, Ctr Reg Bajio, CONACyT Red Divers Biol Occidente Mexicano, Patzcuaro, Michoacan, Mexico
Kiel-Martinez, Ana L.:
Inst Ecol AC, Red Estudios Mol Avanzados, Xalapa, Veracruz, Mexico
Ramirez-Vazquez, Monica:
Inst Ecol AC, Red Estudios Mol Avanzados, Xalapa, Veracruz, Mexico
Univ Nacl Autonoma Mexico, Fac Med, Ciudad De Mexico, Mexico
Guevara-Avendano, Edgar:
Inst Ecol AC, Red Estudios Mol Avanzados, Xalapa, Veracruz, Mexico
Mendez-Bravo, Alejandro:
Univ Nacl Autonoma Mexico, Escuela Nacl Estudios Super Unidad Morelia, Lab Nacl Anal & Sintesis Ecol, Morelia, Mexico
Guerrero-Analco, Jose A.:
Inst Ecol AC, Red Estudios Mol Avanzados, Xalapa, Veracruz, Mexico
Reverchon, Frederique:
Inst Ecol AC, Ctr Reg Bajio, Red Divers Biol Occidente Mexicano, Patzcuaro, Michoacan, Mexico
gold, Gold
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