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Induced systemic resistance responses in perennial ryegrass against Magnaporthe oryzae elicited by semi-purified surfactin lipopeptides and live cells of Bacillus amyloliquefaciens.

ABSTRACT: The suppressive ability of several strains of cyclic lipopeptide-producing Bacillus rhizobacteria to grey leaf spot disease caused by Magnaporthe oryzae has been documented previously; however, the underlying mechanism(s) involved in the induced systemic resistance (ISR) activity in perennial ryegrass (Lolium perenne L.) remains unknown. Root-drench application of solid-phase extraction (SPE)-enriched surfactin and live cells of mutant Bacillus amyloliquefaciens strain FZB42-AK3 (produces surfactin, but not bacillomycin D and fengycin) significantly reduced disease incidence and severity on perennial ryegrass. The application of the treatments revealed a pronounced multilayered ISR defence response activation via timely and enhanced accumulation of hydrogen peroxide (H2O2), elevated cell wall/apoplastic peroxidase activity, and deposition of callose and phenolic/polyphenolic compounds underneath the fungal appressoria in naïve leaves, which was significantly more intense in treated plants than in mock-treated controls. Moreover, a hypersensitive response (HR)-type reaction and enhanced expression of LpPrx (Prx, peroxidase), LpOXO4 (OXO, oxalate oxidase), LpPAL (PAL, phenylalanine ammonia lyase), LpLOXa (LOX, lipoxygenase), LpTHb (putative defensin) and LpDEFa (DEFa, putative defensin) in perennial ryegrass were associated with SPE-enriched surfactin and live AK3 cell treatments, acting as a second layer of defence when pre-invasive defence responses failed. The results indicate that ISR activity following surfactin perception may sensitize H2O2 -mediated defence responses, thereby providing perennial ryegrass with enhanced protection against M.?oryzae.

SUBMITTER: Rahman A

PROVIDER: S-EPMC6638512 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Induced systemic resistance responses in perennial ryegrass against Magnaporthe oryzae elicited by semi-purified surfactin lipopeptides and live cells of Bacillus amyloliquefaciens.

Rahman Alamgir A Uddin Wakar W Wenner Nancy G NG

Molecular plant pathology 20150123 6

The suppressive ability of several strains of cyclic lipopeptide-producing Bacillus rhizobacteria to grey leaf spot disease caused by Magnaporthe oryzae has been documented previously; however, the underlying mechanism(s) involved in the induced systemic resistance (ISR) activity in perennial ryegrass (Lolium perenne L.) remains unknown. Root-drench application of solid-phase extraction (SPE)-enriched surfactin and live cells of mutant Bacillus amyloliquefaciens strain FZB42-AK3 (produces surfac ...[more]

PMID: 25285593

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Project description:BACKGROUND: Perennial ryegrass (Lolium perenne L.) is one of the most important forage and turf grass species of temperate regions worldwide. Its mitochondrial genome is inherited maternally and contains genes that can influence traits of agricultural importance. Moreover, the DNA sequence of mitochondrial genomes has been established and compared for a large number of species in order to characterize evolutionary relationships. Therefore, it is crucial to understand the organization of the mitochondrial genome and how it varies between and within species. Here, we report the first de novo assembly and annotation of the complete mitochondrial genome from perennial ryegrass. RESULTS: Intact mitochondria from perennial ryegrass leaves were isolated and used for mtDNA extraction. The mitochondrial genome was sequenced to a 167-fold coverage using the Roche 454 GS-FLX Titanium platform, and assembled into a circular master molecule of 678,580 bp. A total of 34 proteins, 14 tRNAs and 3 rRNAs are encoded by the mitochondrial genome, giving a total gene space of 48,723 bp (7.2%). Moreover, we identified 149 open reading frames larger than 300 bp and covering 67,410 bp (9.93%), 250 SSRs, 29 tandem repeats, 5 pairs of large repeats, and 96 pairs of short inverted repeats. The genes encoding subunits of the respiratory complexes - nad1 to nad9, cob, cox1 to cox3 and atp1 to atp9 - all showed high expression levels both in absolute numbers and after normalization. CONCLUSIONS: The circular master molecule of the mitochondrial genome from perennial ryegrass presented here constitutes an important tool for future attempts to compare mitochondrial genomes within and between grass species. Our results also demonstrate that mitochondria of perennial ryegrass contain genes crucial for energy production that are well conserved in the mitochondrial genome of monocotyledonous species. The expression analysis gave us first insights into the transcriptome of these mitochondrial genes in perennial ryegrass.

Project description:The lipopeptides produced by Streptomyces bikiniensis have a significant inhibitory effect on Magnaporthe oryzae, but the low yield limits its application. In this study, the anti-M. oryzae activity of the broth of S. bikiniensis HD-087 co-cultured with M. oryzae Guy11 mycelium has risen by 41.22% compared with pure culture, and under induction conditions of adding Guy11-inducer (cell-free supernatant of M. oryzae Guy11), the activity of strain HD-087 improved 61.76%. The result proved that the enhancement effect of Guy11 on the antimicrobial activity of HD-087 was mainly related to metabolites but mycelium cells. Under optimum induction conditions, NRPS gene expression levels of HD-087 were significantly increased by induction with Guy11-inducer, the biomass of HD-087 had no significant change, but crude extract of lipopeptide (CEL) production was 107.4% higher than pure culture, and TLC result under acid hydrolysis showed that the induced culture has one component more than pure culture. To clarify the regulation mechanism of improving lipopeptide production of HD-087 with Guy11-inducer, transcriptomic analysis was performed using RNAseq to compare the induced culture and pure culture. In the induced culture, 943 genes were up-regulated, while 590 genes were down-regulated in DEGs (differentially expressed genes). KEGG results showed that the expression of genes related to amino acid synthesis, fatty acid metabolism, TCA cycle and pyruvate metabolism pathway were significantly increased. The increased expression of genes related to these metabolic pathways provided sufficient precursors for lipopeptide synthesis. Accordingly, key enzyme genes responsible for the synthesis of lipopeptides Srf and NRPS was significantly increased. Quorum sensing related genes OppA and MppA were significantly up-regulated, and then ComP was activated and promoted lipopeptide synthesis. These results provided a scientific basis for using M. oryzae to induce the increase of the production of Streptomyces lipopeptides, and also laid a foundation for further exploring the co-culture mechanisms among different genera.

Dataset Information

Induced systemic resistance responses in perennial ryegrass against Magnaporthe oryzae elicited by semi-purified surfactin lipopeptides and live cells of Bacillus amyloliquefaciens.

Publications

Induced systemic resistance responses in perennial ryegrass against Magnaporthe oryzae elicited by semi-purified surfactin lipopeptides and live cells of Bacillus amyloliquefaciens.

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