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The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts.

Vahabi K, Sherameti I, Bakshi M, Mrozinska A, Ludwig A, Reichelt M, Oelmüller R - BMC Plant Biol. (2015)

Bottom Line: Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the number and expression level of defense/stress-related genes decreases.We propose that exudated compounds from P. indica induce stress and defense responses in the host.Root colonization results in the down-regulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress.

Results: We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the number and expression level of defense/stress-related genes decreases.

Conclusions: We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the down-regulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.

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Related in: MedlinePlus

Phytohormone levels in roots and leaves of Arabidopsis seedlings after exposure toP. indicafor two or six days. The roots and shoots of the seedlings were harvested at day 0, 2 and 6 after exposure to the P. indica plug or an agar plug without mycelium. SA, ABA, JA, cis-OPDA and JA-Ile levels were determined. The values are means ± SEs of 4 independent biological experiments with 5 replications in each experiment.
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Fig4: Phytohormone levels in roots and leaves of Arabidopsis seedlings after exposure toP. indicafor two or six days. The roots and shoots of the seedlings were harvested at day 0, 2 and 6 after exposure to the P. indica plug or an agar plug without mycelium. SA, ABA, JA, cis-OPDA and JA-Ile levels were determined. The values are means ± SEs of 4 independent biological experiments with 5 replications in each experiment.

Mentions: Beneficial plant-microbe interactions are associated with changes in phytohormone levels [15-17]. In order to test whether co-cultivation of Arabidopsis roots with P. indica affects the phytohormone levels, the amounts of jasmonic acid (JA) and its active form JA-isoleucine (JA-Ile), 12-oxo-phytodienoic acid (OPDA), abscisic acid (ABA) and salicylic acid (SA) were determined in the roots and shoots of seedlings either exposed to P. indica or mock-treated. Interestingly, we observed the strongest up-regulation of the phytohormone levels in both roots and shoots two days after co-cultivation. The phytohormone levels decreased significantly in both roots and shoots after six days of co-cultivation (Figure 4). Since the hormones are involved in various types of stress and defense responses, the results indicate that exudated compounds from the fungus induce stress hormones in the roots and systemically also in the leaves. Their level declines as soon as a physical contact between the two organisms is established.Figure 4


The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts.

Vahabi K, Sherameti I, Bakshi M, Mrozinska A, Ludwig A, Reichelt M, Oelmüller R - BMC Plant Biol. (2015)

Phytohormone levels in roots and leaves of Arabidopsis seedlings after exposure toP. indicafor two or six days. The roots and shoots of the seedlings were harvested at day 0, 2 and 6 after exposure to the P. indica plug or an agar plug without mycelium. SA, ABA, JA, cis-OPDA and JA-Ile levels were determined. The values are means ± SEs of 4 independent biological experiments with 5 replications in each experiment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4384353&req=5

Fig4: Phytohormone levels in roots and leaves of Arabidopsis seedlings after exposure toP. indicafor two or six days. The roots and shoots of the seedlings were harvested at day 0, 2 and 6 after exposure to the P. indica plug or an agar plug without mycelium. SA, ABA, JA, cis-OPDA and JA-Ile levels were determined. The values are means ± SEs of 4 independent biological experiments with 5 replications in each experiment.
Mentions: Beneficial plant-microbe interactions are associated with changes in phytohormone levels [15-17]. In order to test whether co-cultivation of Arabidopsis roots with P. indica affects the phytohormone levels, the amounts of jasmonic acid (JA) and its active form JA-isoleucine (JA-Ile), 12-oxo-phytodienoic acid (OPDA), abscisic acid (ABA) and salicylic acid (SA) were determined in the roots and shoots of seedlings either exposed to P. indica or mock-treated. Interestingly, we observed the strongest up-regulation of the phytohormone levels in both roots and shoots two days after co-cultivation. The phytohormone levels decreased significantly in both roots and shoots after six days of co-cultivation (Figure 4). Since the hormones are involved in various types of stress and defense responses, the results indicate that exudated compounds from the fungus induce stress hormones in the roots and systemically also in the leaves. Their level declines as soon as a physical contact between the two organisms is established.Figure 4

Bottom Line: Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the number and expression level of defense/stress-related genes decreases.We propose that exudated compounds from P. indica induce stress and defense responses in the host.Root colonization results in the down-regulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress.

Results: We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the number and expression level of defense/stress-related genes decreases.

Conclusions: We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the down-regulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.

Show MeSH
Related in: MedlinePlus