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The effects of glucosinolates and their breakdown products on necrotrophic fungi.

Buxdorf K, Yaffe H, Barda O, Levy M - PLoS ONE (2013)

Bottom Line: We also found that B. cinerea stimulates the accumulation of glucosinolates to a greater extent than A. brassicicola.In our work with A. brassicicola, we found that the type of glucosinolate-breakdown product is more important than the type of glucosinolate from which that product was derived, as demonstrated by the sensitivity of the Ler background and the sensitivity gained in Col-0 plants expressing epithiospecifier protein both of which accumulate simple nitrile and epithionitriles, but not isothiocyanates.Furthermore, in vivo, hydrolysis products of indole glucosinolates were found to be involved in defense against B. cinerea, but not in the host response to A. brassicicola.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.

ABSTRACT
Glucosinolates are a diverse class of S- and N-containing secondary metabolites that play a variety of roles in plant defense. In this study, we used Arabidopsis thaliana mutants that contain different amounts of glucosinolates and glucosinolate-breakdown products to study the effects of these phytochemicals on phytopathogenic fungi. We compared the fungus Botrytis cinerea, which infects a variety of hosts, with the Brassicaceae-specific fungus Alternaria brassicicola. B. cinerea isolates showed variable composition-dependent sensitivity to glucosinolates and their hydrolysis products, while A. brassicicola was more strongly affected by aliphatic glucosinolates and isothiocyanates as decomposition products. We also found that B. cinerea stimulates the accumulation of glucosinolates to a greater extent than A. brassicicola. In our work with A. brassicicola, we found that the type of glucosinolate-breakdown product is more important than the type of glucosinolate from which that product was derived, as demonstrated by the sensitivity of the Ler background and the sensitivity gained in Col-0 plants expressing epithiospecifier protein both of which accumulate simple nitrile and epithionitriles, but not isothiocyanates. Furthermore, in vivo, hydrolysis products of indole glucosinolates were found to be involved in defense against B. cinerea, but not in the host response to A. brassicicola. We suggest that the Brassicaceae-specialist A. brassicicola has adapted to the presence of indolic glucosinolates and can cope with their hydrolysis products. In contrast, some isolates of the generalist B. cinerea are more sensitive to these phytochemicals.

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Effects of indole glucosinolate and camalexin on fungal pathogenicity.Arabidopsis mutants cyp79B2/B3 and pad3, which have altered total glucosinolate and/or camalexin content, and their corresponding wild-type background (Col-0) were inoculated with B. cinerea (B05.10 or grape isolate) or A. brassicicola. Lesion size was measured 72 h after inoculation (upper and middle panels) with B. cinerea and 120 to 192 h after inoculation with A. brassicicola (lower panel). Average lesion sizes from 30 leaves of each genotype are presented along with and the standard error of each average. All numbers are presented as the relative percentage to their corresponding background wild-type. Different letters above the columns indicate statistically significant differences at P<0.05, as determined using the Kruskal-Wallis test and Dunn’s test.
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pone-0070771-g002: Effects of indole glucosinolate and camalexin on fungal pathogenicity.Arabidopsis mutants cyp79B2/B3 and pad3, which have altered total glucosinolate and/or camalexin content, and their corresponding wild-type background (Col-0) were inoculated with B. cinerea (B05.10 or grape isolate) or A. brassicicola. Lesion size was measured 72 h after inoculation (upper and middle panels) with B. cinerea and 120 to 192 h after inoculation with A. brassicicola (lower panel). Average lesion sizes from 30 leaves of each genotype are presented along with and the standard error of each average. All numbers are presented as the relative percentage to their corresponding background wild-type. Different letters above the columns indicate statistically significant differences at P<0.05, as determined using the Kruskal-Wallis test and Dunn’s test.

Mentions: To determine whether indolic glucosinolates affect fungal pathogenesis we used the Arabidopsis cyp79B2 cyp79B3 (cyp79B2/B3) double mutant with a Col-0 background, which does not accumulate indolic glucosinolates or camalexin and whose aliphatic glucosinolates levels are 50% or less than the aliphatic glucosinolates levels observed in the wild-type [49], [50]. This double mutant exhibited enhanced sensitivity to A. brassicicola (Figure 2, lower panel), and a moderately higher (although not always significant so) levels of sensitivity to the B05.10 B. cinerea isolate and to the grape isolate as compared with wild-type plants (Figure 2, upper and middle panels). In the plants in which this mutation was expressed against the Ws-0 background, the same pattern of resistance was observed for interactions with A. brassicicola and the B05.10 isolate of B. cinerea (Figure S2). Since the cyp79B2/B3 double mutant also has impaired camalexin accumulation [41], we compared its sensitivity to that of the camalexin-deficient mutant pad3[44], [51]. As shown in Figure 2, pad3 plants were more sensitive than the wild-type to A. brassicicola and B. cinerea. However, the sensitivities of the pad3 plants did not differ from those of the cyp79B2/B3 mutant.


The effects of glucosinolates and their breakdown products on necrotrophic fungi.

Buxdorf K, Yaffe H, Barda O, Levy M - PLoS ONE (2013)

Effects of indole glucosinolate and camalexin on fungal pathogenicity.Arabidopsis mutants cyp79B2/B3 and pad3, which have altered total glucosinolate and/or camalexin content, and their corresponding wild-type background (Col-0) were inoculated with B. cinerea (B05.10 or grape isolate) or A. brassicicola. Lesion size was measured 72 h after inoculation (upper and middle panels) with B. cinerea and 120 to 192 h after inoculation with A. brassicicola (lower panel). Average lesion sizes from 30 leaves of each genotype are presented along with and the standard error of each average. All numbers are presented as the relative percentage to their corresponding background wild-type. Different letters above the columns indicate statistically significant differences at P<0.05, as determined using the Kruskal-Wallis test and Dunn’s test.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3733641&req=5

pone-0070771-g002: Effects of indole glucosinolate and camalexin on fungal pathogenicity.Arabidopsis mutants cyp79B2/B3 and pad3, which have altered total glucosinolate and/or camalexin content, and their corresponding wild-type background (Col-0) were inoculated with B. cinerea (B05.10 or grape isolate) or A. brassicicola. Lesion size was measured 72 h after inoculation (upper and middle panels) with B. cinerea and 120 to 192 h after inoculation with A. brassicicola (lower panel). Average lesion sizes from 30 leaves of each genotype are presented along with and the standard error of each average. All numbers are presented as the relative percentage to their corresponding background wild-type. Different letters above the columns indicate statistically significant differences at P<0.05, as determined using the Kruskal-Wallis test and Dunn’s test.
Mentions: To determine whether indolic glucosinolates affect fungal pathogenesis we used the Arabidopsis cyp79B2 cyp79B3 (cyp79B2/B3) double mutant with a Col-0 background, which does not accumulate indolic glucosinolates or camalexin and whose aliphatic glucosinolates levels are 50% or less than the aliphatic glucosinolates levels observed in the wild-type [49], [50]. This double mutant exhibited enhanced sensitivity to A. brassicicola (Figure 2, lower panel), and a moderately higher (although not always significant so) levels of sensitivity to the B05.10 B. cinerea isolate and to the grape isolate as compared with wild-type plants (Figure 2, upper and middle panels). In the plants in which this mutation was expressed against the Ws-0 background, the same pattern of resistance was observed for interactions with A. brassicicola and the B05.10 isolate of B. cinerea (Figure S2). Since the cyp79B2/B3 double mutant also has impaired camalexin accumulation [41], we compared its sensitivity to that of the camalexin-deficient mutant pad3[44], [51]. As shown in Figure 2, pad3 plants were more sensitive than the wild-type to A. brassicicola and B. cinerea. However, the sensitivities of the pad3 plants did not differ from those of the cyp79B2/B3 mutant.

Bottom Line: We also found that B. cinerea stimulates the accumulation of glucosinolates to a greater extent than A. brassicicola.In our work with A. brassicicola, we found that the type of glucosinolate-breakdown product is more important than the type of glucosinolate from which that product was derived, as demonstrated by the sensitivity of the Ler background and the sensitivity gained in Col-0 plants expressing epithiospecifier protein both of which accumulate simple nitrile and epithionitriles, but not isothiocyanates.Furthermore, in vivo, hydrolysis products of indole glucosinolates were found to be involved in defense against B. cinerea, but not in the host response to A. brassicicola.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.

ABSTRACT
Glucosinolates are a diverse class of S- and N-containing secondary metabolites that play a variety of roles in plant defense. In this study, we used Arabidopsis thaliana mutants that contain different amounts of glucosinolates and glucosinolate-breakdown products to study the effects of these phytochemicals on phytopathogenic fungi. We compared the fungus Botrytis cinerea, which infects a variety of hosts, with the Brassicaceae-specific fungus Alternaria brassicicola. B. cinerea isolates showed variable composition-dependent sensitivity to glucosinolates and their hydrolysis products, while A. brassicicola was more strongly affected by aliphatic glucosinolates and isothiocyanates as decomposition products. We also found that B. cinerea stimulates the accumulation of glucosinolates to a greater extent than A. brassicicola. In our work with A. brassicicola, we found that the type of glucosinolate-breakdown product is more important than the type of glucosinolate from which that product was derived, as demonstrated by the sensitivity of the Ler background and the sensitivity gained in Col-0 plants expressing epithiospecifier protein both of which accumulate simple nitrile and epithionitriles, but not isothiocyanates. Furthermore, in vivo, hydrolysis products of indole glucosinolates were found to be involved in defense against B. cinerea, but not in the host response to A. brassicicola. We suggest that the Brassicaceae-specialist A. brassicicola has adapted to the presence of indolic glucosinolates and can cope with their hydrolysis products. In contrast, some isolates of the generalist B. cinerea are more sensitive to these phytochemicals.

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