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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

Levels of defense-related enzymes in leaves of tomatoes with mycorrhizal colonization and pathogen infection. Wild-type (WT) and mutant plants (35S::PS and spr2) of tomato 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), LOX (B), PAL (C), and chitinase (D). Enzymatic activities were analyzed 18 (a), 65 (b), 100 (c) and 140 h (d) after pathogen inoculation. 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. Three tomato genotypes included: (1) WT: wild type plant; (2) 35S::PS: Prosystemin-overexpressing 35S::PS plant; (3) spr2: JA biosynthesis mutant plant. 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 4: Levels of defense-related enzymes in leaves of tomatoes with mycorrhizal colonization and pathogen infection. Wild-type (WT) and mutant plants (35S::PS and spr2) of tomato 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), LOX (B), PAL (C), and chitinase (D). Enzymatic activities were analyzed 18 (a), 65 (b), 100 (c) and 140 h (d) after pathogen inoculation. 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. Three tomato genotypes included: (1) WT: wild type plant; (2) 35S::PS: Prosystemin-overexpressing 35S::PS plant; (3) spr2: JA biosynthesis mutant plant. 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: Three tomato genotypes: a WT plant, a JA biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant, were used to identify the role of the JA signaling pathway in mycorrhiza-induced disease resistance against A. solani. The plants of the three genotypes were subjected to the same four treatments as above. There was no significant difference in activities of the four defense-related enzymes in control plants of the three genotypes (Figures 4A–D). However, the three genotypes showed large differences in activities of the four defense-related enzymes in response to pathogen infection (As) and dual inoculation with the pathogen and mycorrhizal fungus (Fm+As). The 35S::PS plants showed higher induction of enzymatic activities in A. solani-inoculated plants compared to the other two genotypes. Most importantly, mycorrhizal pre-inoculated 35S::PS plants showed the highest induction of enzymatic activities (Figures 4A–D). β-1,3-Glucanase activity in treatment Fm+As was increased by 1083.7, 291.3, and 495.5% at 100 h post pathogen inoculation compared with that in treatments CK, As, and Fm, respectively (Figure 4Ac). Similarly, chitinase activity in treatment Fm+As was increased by 795.2, 161.5, and 498.8% at 65 h compared with the other three treatments (Figure 4Db). Similar trends were observed for LOX and PAL activities (Figures 4B,C). The LOX and PAL activities were increased in mycorrhizal pre-inoculated 35S::PS and WT plants after pathogen inoculation, but 35S::PS plants exhibited significantly higher LOX and PAL activities as compared to WT plants (Figures 4B,C). The 35S::PS plants showed 48.5, 125.0, 56.0, and 111.4% higher PAL activity in treatment Fm+As than that of WT plants 18, 65, 100, and 140 h after pathogen inoculation, respectively (Figure 4Ca–d). In contrast, the four tested enzymes were not induced in the spr2 plants in response to pathogen inoculation (As) and dual inoculation (Fm+As) (Figures 4A–D).


Enhanced tomato disease resistance primed by arbuscular mycorrhizal fungus.

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

Levels of defense-related enzymes in leaves of tomatoes with mycorrhizal colonization and pathogen infection. Wild-type (WT) and mutant plants (35S::PS and spr2) of tomato 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), LOX (B), PAL (C), and chitinase (D). Enzymatic activities were analyzed 18 (a), 65 (b), 100 (c) and 140 h (d) after pathogen inoculation. 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. Three tomato genotypes included: (1) WT: wild type plant; (2) 35S::PS: Prosystemin-overexpressing 35S::PS plant; (3) spr2: JA biosynthesis mutant plant. 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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Related In: Results  -  Collection

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Figure 4: Levels of defense-related enzymes in leaves of tomatoes with mycorrhizal colonization and pathogen infection. Wild-type (WT) and mutant plants (35S::PS and spr2) of tomato 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), LOX (B), PAL (C), and chitinase (D). Enzymatic activities were analyzed 18 (a), 65 (b), 100 (c) and 140 h (d) after pathogen inoculation. 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. Three tomato genotypes included: (1) WT: wild type plant; (2) 35S::PS: Prosystemin-overexpressing 35S::PS plant; (3) spr2: JA biosynthesis mutant plant. 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: Three tomato genotypes: a WT plant, a JA biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant, were used to identify the role of the JA signaling pathway in mycorrhiza-induced disease resistance against A. solani. The plants of the three genotypes were subjected to the same four treatments as above. There was no significant difference in activities of the four defense-related enzymes in control plants of the three genotypes (Figures 4A–D). However, the three genotypes showed large differences in activities of the four defense-related enzymes in response to pathogen infection (As) and dual inoculation with the pathogen and mycorrhizal fungus (Fm+As). The 35S::PS plants showed higher induction of enzymatic activities in A. solani-inoculated plants compared to the other two genotypes. Most importantly, mycorrhizal pre-inoculated 35S::PS plants showed the highest induction of enzymatic activities (Figures 4A–D). β-1,3-Glucanase activity in treatment Fm+As was increased by 1083.7, 291.3, and 495.5% at 100 h post pathogen inoculation compared with that in treatments CK, As, and Fm, respectively (Figure 4Ac). Similarly, chitinase activity in treatment Fm+As was increased by 795.2, 161.5, and 498.8% at 65 h compared with the other three treatments (Figure 4Db). Similar trends were observed for LOX and PAL activities (Figures 4B,C). The LOX and PAL activities were increased in mycorrhizal pre-inoculated 35S::PS and WT plants after pathogen inoculation, but 35S::PS plants exhibited significantly higher LOX and PAL activities as compared to WT plants (Figures 4B,C). The 35S::PS plants showed 48.5, 125.0, 56.0, and 111.4% higher PAL activity in treatment Fm+As than that of WT plants 18, 65, 100, and 140 h after pathogen inoculation, respectively (Figure 4Ca–d). In contrast, the four tested enzymes were not induced in the spr2 plants in response to pathogen inoculation (As) and dual inoculation (Fm+As) (Figures 4A–D).

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