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Enhanced tomato disease resistance primed by arbuscular mycorrhizal fungus.

Song Y, Chen D, Lu K, Sun Z, Zeng R - Front Plant Sci (2015)

Bottom Line: Three tomato genotypes: a Castlemart wild-type (WT) plant, a jasmonate (JA) biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant were used to examine the role of the JA signaling pathway in AMF-primed disease defense.Pathogen infection on mycorrhizal 35S::PS plants led to higher induction of defense-related genes and enzymes relative to WT plants.However, pathogen infection did not induce these genes and enzymes in mycorrhizal spr2 mutant plants.

View Article: PubMed Central - PubMed

Affiliation: College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou China ; State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, South China Agricultural University, Guangzhou China.

ABSTRACT
Roots of most terrestrial plants form symbiotic associations (mycorrhiza) with soil- borne arbuscular mycorrhizal fungi (AMF). Many studies show that mycorrhizal colonization enhances plant resistance against pathogenic fungi. However, the mechanism of mycorrhiza-induced disease resistance remains equivocal. In this study, we found that mycorrhizal inoculation with AMF Funneliformis mosseae significantly alleviated tomato (Solanum lycopersicum Mill.) early blight disease caused by Alternaria solani Sorauer. AMF pre-inoculation led to significant increases in activities of β-1,3-glucanase, chitinase, phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX) in tomato leaves upon pathogen inoculation. Mycorrhizal inoculation alone did not influence the transcripts of most genes tested. However, pathogen attack on AMF-inoculated plants provoked strong defense responses of three genes encoding pathogenesis-related proteins, PR1, PR2, and PR3, as well as defense-related genes LOX, AOC, and PAL, in tomato leaves. The induction of defense responses in AMF pre-inoculated plants was much higher and more rapid than that in un-inoculated plants in present of pathogen infection. Three tomato genotypes: a Castlemart wild-type (WT) plant, a jasmonate (JA) biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant were used to examine the role of the JA signaling pathway in AMF-primed disease defense. Pathogen infection on mycorrhizal 35S::PS plants led to higher induction of defense-related genes and enzymes relative to WT plants. However, pathogen infection did not induce these genes and enzymes in mycorrhizal spr2 mutant plants. Bioassays showed that 35S::PS plants were more resistant and spr2 plants were more susceptible to early blight compared with WT plants. Our finding indicates that mycorrhizal colonization enhances tomato resistance to early blight by priming systemic defense response, and the JA signaling pathway is essential for mycorrhiza-primed disease resistance.

No MeSH data available.


Related in: MedlinePlus

Activity levels of defense-related enzymes in tomato leaves in response to mycorrhizal colonization and pathogen infection. The tomatoes were pre-inoculated with mycorrhizal fungus Funneliformis mosseae and later inoculated with A. solani, the causal agent of early blight disease of tomato. Four defense-related enzymes are β-1,3-glucanase (A), lipoxygenase (LOX) (B), phenylalanine ammonia-lyase (PAL) (C), and chitinase (D). Four treatments included: (1) CK: control plants without pathogen and mycorrhizal inoculation; (2) As: plants inoculated with A. solani only; (3) Fm: plants inoculated with F. mosseae only; (4) Fm+As: plants inoculated with both F. mosseae and A. solani. Values are means ± SE from three sets of independent experiments with three pots per treatment for each set of experiments. Significant differences among treatments were tested at P = 0.05 by Tukey post hoc test.
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Figure 2: Activity levels of defense-related enzymes in tomato leaves in response to mycorrhizal colonization and pathogen infection. The tomatoes were pre-inoculated with mycorrhizal fungus Funneliformis mosseae and later inoculated with A. solani, the causal agent of early blight disease of tomato. Four defense-related enzymes are β-1,3-glucanase (A), lipoxygenase (LOX) (B), phenylalanine ammonia-lyase (PAL) (C), and chitinase (D). Four treatments included: (1) CK: control plants without pathogen and mycorrhizal inoculation; (2) As: plants inoculated with A. solani only; (3) Fm: plants inoculated with F. mosseae only; (4) Fm+As: plants inoculated with both F. mosseae and A. solani. Values are means ± SE from three sets of independent experiments with three pots per treatment for each set of experiments. Significant differences among treatments were tested at P = 0.05 by Tukey post hoc test.

Mentions: To examine effects of mycorrhizal colonization on defense responses in host plants in presence of pathogen infection tomato plants were subjected to four treatments: (1) CK: control without fungal inoculation; (2) As: inoculation with A. solani; (3) Fm: inoculation with F. mosseae; (4) Fm+As: inoculation with both F. mosseae and A. solani. Four defense-related enzymes, including PAL, LOX, chitinase, and β-1,3-glucanase were analyzed in the leaves of tomato plants. Mycorrhizal pre-inoculation significantly enhanced activities of the four enzymes in the leaves upon pathogen infection (Figures 2A–D). The activities of all tested enzymes were significantly higher in treatment Fm+As after the pathogen inoculation and reached a maximum at 65 h. The activity of β-1,3-glucanase was increased by 34.7, 33.3, and 28.8%, respectively, relative to those in treatments CK, As, and Fm 65 h post the pathogen inoculation (Figure 2A). However, the activity of β-1,3-glucanase did not differ significantly between the other treatments (CK, As, and Fm) (Figure 2A).


Enhanced tomato disease resistance primed by arbuscular mycorrhizal fungus.

Song Y, Chen D, Lu K, Sun Z, Zeng R - Front Plant Sci (2015)

Activity levels of defense-related enzymes in tomato leaves in response to mycorrhizal colonization and pathogen infection. The tomatoes were pre-inoculated with mycorrhizal fungus Funneliformis mosseae and later inoculated with A. solani, the causal agent of early blight disease of tomato. Four defense-related enzymes are β-1,3-glucanase (A), lipoxygenase (LOX) (B), phenylalanine ammonia-lyase (PAL) (C), and chitinase (D). Four treatments included: (1) CK: control plants without pathogen and mycorrhizal inoculation; (2) As: plants inoculated with A. solani only; (3) Fm: plants inoculated with F. mosseae only; (4) Fm+As: plants inoculated with both F. mosseae and A. solani. Values are means ± SE from three sets of independent experiments with three pots per treatment for each set of experiments. Significant differences among treatments were tested at P = 0.05 by Tukey post hoc test.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585261&req=5

Figure 2: Activity levels of defense-related enzymes in tomato leaves in response to mycorrhizal colonization and pathogen infection. The tomatoes were pre-inoculated with mycorrhizal fungus Funneliformis mosseae and later inoculated with A. solani, the causal agent of early blight disease of tomato. Four defense-related enzymes are β-1,3-glucanase (A), lipoxygenase (LOX) (B), phenylalanine ammonia-lyase (PAL) (C), and chitinase (D). Four treatments included: (1) CK: control plants without pathogen and mycorrhizal inoculation; (2) As: plants inoculated with A. solani only; (3) Fm: plants inoculated with F. mosseae only; (4) Fm+As: plants inoculated with both F. mosseae and A. solani. Values are means ± SE from three sets of independent experiments with three pots per treatment for each set of experiments. Significant differences among treatments were tested at P = 0.05 by Tukey post hoc test.
Mentions: To examine effects of mycorrhizal colonization on defense responses in host plants in presence of pathogen infection tomato plants were subjected to four treatments: (1) CK: control without fungal inoculation; (2) As: inoculation with A. solani; (3) Fm: inoculation with F. mosseae; (4) Fm+As: inoculation with both F. mosseae and A. solani. Four defense-related enzymes, including PAL, LOX, chitinase, and β-1,3-glucanase were analyzed in the leaves of tomato plants. Mycorrhizal pre-inoculation significantly enhanced activities of the four enzymes in the leaves upon pathogen infection (Figures 2A–D). The activities of all tested enzymes were significantly higher in treatment Fm+As after the pathogen inoculation and reached a maximum at 65 h. The activity of β-1,3-glucanase was increased by 34.7, 33.3, and 28.8%, respectively, relative to those in treatments CK, As, and Fm 65 h post the pathogen inoculation (Figure 2A). However, the activity of β-1,3-glucanase did not differ significantly between the other treatments (CK, As, and Fm) (Figure 2A).

Bottom Line: Three tomato genotypes: a Castlemart wild-type (WT) plant, a jasmonate (JA) biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant were used to examine the role of the JA signaling pathway in AMF-primed disease defense.Pathogen infection on mycorrhizal 35S::PS plants led to higher induction of defense-related genes and enzymes relative to WT plants.However, pathogen infection did not induce these genes and enzymes in mycorrhizal spr2 mutant plants.

View Article: PubMed Central - PubMed

Affiliation: College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou China ; State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, South China Agricultural University, Guangzhou China.

ABSTRACT
Roots of most terrestrial plants form symbiotic associations (mycorrhiza) with soil- borne arbuscular mycorrhizal fungi (AMF). Many studies show that mycorrhizal colonization enhances plant resistance against pathogenic fungi. However, the mechanism of mycorrhiza-induced disease resistance remains equivocal. In this study, we found that mycorrhizal inoculation with AMF Funneliformis mosseae significantly alleviated tomato (Solanum lycopersicum Mill.) early blight disease caused by Alternaria solani Sorauer. AMF pre-inoculation led to significant increases in activities of β-1,3-glucanase, chitinase, phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX) in tomato leaves upon pathogen inoculation. Mycorrhizal inoculation alone did not influence the transcripts of most genes tested. However, pathogen attack on AMF-inoculated plants provoked strong defense responses of three genes encoding pathogenesis-related proteins, PR1, PR2, and PR3, as well as defense-related genes LOX, AOC, and PAL, in tomato leaves. The induction of defense responses in AMF pre-inoculated plants was much higher and more rapid than that in un-inoculated plants in present of pathogen infection. Three tomato genotypes: a Castlemart wild-type (WT) plant, a jasmonate (JA) biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant were used to examine the role of the JA signaling pathway in AMF-primed disease defense. Pathogen infection on mycorrhizal 35S::PS plants led to higher induction of defense-related genes and enzymes relative to WT plants. However, pathogen infection did not induce these genes and enzymes in mycorrhizal spr2 mutant plants. Bioassays showed that 35S::PS plants were more resistant and spr2 plants were more susceptible to early blight compared with WT plants. Our finding indicates that mycorrhizal colonization enhances tomato resistance to early blight by priming systemic defense response, and the JA signaling pathway is essential for mycorrhiza-primed disease resistance.

No MeSH data available.


Related in: MedlinePlus