Microenvironmental interplay predominated by beneficial Aspergillus abates fungal pathogen incidence in paddy environment.

Microenvironmental interplay predominated by beneficial Aspergillus abates fungal pathogen incidence in paddy environment.

Environ Sci Technol. 2019 Oct 20;:

Authors: Fan X, Matsumoto H, Wang Y, Hu Y, Liu Y, Fang H, Nitkiewicz B, Lau SYL, Wang Q, Fang H, Wang M

Abstract
Rice fungal pathogens-responsible severe rice yield loss and biotoxin contamination cause increasing concerns on environmental safety and public health. In paddy environment, we observed that the asymptomatic rice phyllosphere microenvironment was dominated by an indigenous fungus, Aspergillus cvjetkovicii, which positively correlated with alleviated incidence of Magnaporthe oryzae, one of the most aggressive plant pathogens. Through the comparative metabolic profiling for rice phyllosphere microenvironment, two metabolites were assigned as exclusively-enriched metabolic markers in asymptomatic phyllosphere and increased remarkably in a population-dependent manner with A. cvjetkovicii. These two metabolites evidenced to be produced by A. cvjetkovicii in either phyllosphere microenvironment or artificial media, were purified and identified as 2(3H)-benzofuranone and azulene, respectively by GC-QqQ-MS/MS and NMR analyses. Combining with bioassay analysis in vivo and in vitro, we found 2(3H)-benzofuranone and azulene exerted dissimilar actions at the stage of infection-related development of M. oryzae. A. cvjetkovicii produced 2(3H)-benzofuranone at the early stage to suppress MoPer1 gene expression leading to inhibited mycelial growth, while azulene produced lately was involved in block of appressorium formation by down-regulation of MgRac1. More profoundly, the microenvironmental interplay dominated by A. cvjetkovicii significantly blocked M. oryzae epidemics in paddy environment from 54.7% to 68.5% (p < 0.05). Our study first demonstrated implication of the microenvironmental interplay dominated by indigenous and beneficial fungus to ecological balance and safety of paddy environment.

PMID: 31631659 [PubMed – as supplied by publisher]

Source: Industry