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Camalexin contributes to the partial resistance of Arabidopsis thaliana to the biotrophic soilborne protist Plasmodiophora brassicae.

Lemarié S, Robert-Seilaniantz A, Lariagon C, Lemoine J, Marnet N, Levrel A, Jubault M, Manzanares-Dauleux MJ, Gravot A - Front Plant Sci (2015)

Bottom Line: This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance.The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development.Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

View Article: PubMed Central - PubMed

Affiliation: UMR1349 IGEPP, INRA Le Rheu, France.

ABSTRACT
Camalexin has been reported to play defensive functions against several pathogens in Arabidopsis. In this study, we investigated the possible role of camalexin accumulation in two Arabidopsis genotypes with different levels of basal resistance to the compatible eH strain of the clubroot agent Plasmodiophora brassicae. Camalexin biosynthesis was induced in infected roots of both Col-0 (susceptible) and Bur-0 (partially resistant) accessions during the secondary phase of infection. However, the level of accumulation was four-to-seven times higher in Bur-0 than Col-0. This was associated with the enhanced transcription of a set of camalexin biosynthetic P450 genes in Bur-0: CYP71A13, CYP71A12, and CYP79B2. This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance. Clubroot-triggered biosynthesis of camalexin may also participate in basal defense in Col-0, as gall symptoms and pathogen development were enhanced in the pad3 mutant (Col-0 genetic background), which is defective in camalexin biosynthesis. Clubroot and camalexin responses were then studied in Heterogeneous Inbred Families (HIF) lines derived from a cross between Bur-0 and Col-0. The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development. Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

No MeSH data available.


Related in: MedlinePlus

(A) Safranin and blue cotton and (B) aniline blue stained radial sections of roots infected by Plasmodiophora brassicae in the partially resistant accession Bur-0 and the susceptible accession Col-0. Roots were sampled at 17 dpi, then fixed and immobilized in resin as described in Materials and Methods part. (A,B), Histological sections were cut with a microtome and stained in cotton blue and safranin to visualize pathogen plasmodia (colored in blue in A), plant cell walls (colored in red in A), and vascular vessels colored by aniline blue in (B) respectively. White arrows indicate plasmodia structures in infected cells. For each condition, the image shown is representative of the observations performed on at least six independent root samples. Annotations: vv, vascular vessels; c, cortex. The scale bars indicate 100 μm.
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Figure 6: (A) Safranin and blue cotton and (B) aniline blue stained radial sections of roots infected by Plasmodiophora brassicae in the partially resistant accession Bur-0 and the susceptible accession Col-0. Roots were sampled at 17 dpi, then fixed and immobilized in resin as described in Materials and Methods part. (A,B), Histological sections were cut with a microtome and stained in cotton blue and safranin to visualize pathogen plasmodia (colored in blue in A), plant cell walls (colored in red in A), and vascular vessels colored by aniline blue in (B) respectively. White arrows indicate plasmodia structures in infected cells. For each condition, the image shown is representative of the observations performed on at least six independent root samples. Annotations: vv, vascular vessels; c, cortex. The scale bars indicate 100 μm.

Mentions: Intracellular secondary plasmodia of P. brassicae were visualized using cotton blue and safranin staining of sections of infected Col-0 and Bur-0 roots. At 14 dpi, the outer cortex layer in both genotypes showed enlarged and disorganized cells, which are characteristic of clubroot infection. At this time point, however, the disorganization and hypertrophy of stele cells appeared to be more pronounced in Col-0 than in Bur-0, and plasmodia in central cylinder cells were smaller in Bur-0 than in Col-0 (data not shown). At 17 dpi, infected Col-0 roots displayed maximal stele cell hypertrophy associated with a highly reduced and disorganized vascular system. In comparison, infected Bur-0 roots showed lower levels of cellular hypertrophy and weak disorganization of vascular tissues (Figures 6A,B).


Camalexin contributes to the partial resistance of Arabidopsis thaliana to the biotrophic soilborne protist Plasmodiophora brassicae.

Lemarié S, Robert-Seilaniantz A, Lariagon C, Lemoine J, Marnet N, Levrel A, Jubault M, Manzanares-Dauleux MJ, Gravot A - Front Plant Sci (2015)

(A) Safranin and blue cotton and (B) aniline blue stained radial sections of roots infected by Plasmodiophora brassicae in the partially resistant accession Bur-0 and the susceptible accession Col-0. Roots were sampled at 17 dpi, then fixed and immobilized in resin as described in Materials and Methods part. (A,B), Histological sections were cut with a microtome and stained in cotton blue and safranin to visualize pathogen plasmodia (colored in blue in A), plant cell walls (colored in red in A), and vascular vessels colored by aniline blue in (B) respectively. White arrows indicate plasmodia structures in infected cells. For each condition, the image shown is representative of the observations performed on at least six independent root samples. Annotations: vv, vascular vessels; c, cortex. The scale bars indicate 100 μm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4508518&req=5

Figure 6: (A) Safranin and blue cotton and (B) aniline blue stained radial sections of roots infected by Plasmodiophora brassicae in the partially resistant accession Bur-0 and the susceptible accession Col-0. Roots were sampled at 17 dpi, then fixed and immobilized in resin as described in Materials and Methods part. (A,B), Histological sections were cut with a microtome and stained in cotton blue and safranin to visualize pathogen plasmodia (colored in blue in A), plant cell walls (colored in red in A), and vascular vessels colored by aniline blue in (B) respectively. White arrows indicate plasmodia structures in infected cells. For each condition, the image shown is representative of the observations performed on at least six independent root samples. Annotations: vv, vascular vessels; c, cortex. The scale bars indicate 100 μm.
Mentions: Intracellular secondary plasmodia of P. brassicae were visualized using cotton blue and safranin staining of sections of infected Col-0 and Bur-0 roots. At 14 dpi, the outer cortex layer in both genotypes showed enlarged and disorganized cells, which are characteristic of clubroot infection. At this time point, however, the disorganization and hypertrophy of stele cells appeared to be more pronounced in Col-0 than in Bur-0, and plasmodia in central cylinder cells were smaller in Bur-0 than in Col-0 (data not shown). At 17 dpi, infected Col-0 roots displayed maximal stele cell hypertrophy associated with a highly reduced and disorganized vascular system. In comparison, infected Bur-0 roots showed lower levels of cellular hypertrophy and weak disorganization of vascular tissues (Figures 6A,B).

Bottom Line: This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance.The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development.Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

View Article: PubMed Central - PubMed

Affiliation: UMR1349 IGEPP, INRA Le Rheu, France.

ABSTRACT
Camalexin has been reported to play defensive functions against several pathogens in Arabidopsis. In this study, we investigated the possible role of camalexin accumulation in two Arabidopsis genotypes with different levels of basal resistance to the compatible eH strain of the clubroot agent Plasmodiophora brassicae. Camalexin biosynthesis was induced in infected roots of both Col-0 (susceptible) and Bur-0 (partially resistant) accessions during the secondary phase of infection. However, the level of accumulation was four-to-seven times higher in Bur-0 than Col-0. This was associated with the enhanced transcription of a set of camalexin biosynthetic P450 genes in Bur-0: CYP71A13, CYP71A12, and CYP79B2. This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance. Clubroot-triggered biosynthesis of camalexin may also participate in basal defense in Col-0, as gall symptoms and pathogen development were enhanced in the pad3 mutant (Col-0 genetic background), which is defective in camalexin biosynthesis. Clubroot and camalexin responses were then studied in Heterogeneous Inbred Families (HIF) lines derived from a cross between Bur-0 and Col-0. The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development. Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

No MeSH data available.


Related in: MedlinePlus