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Abscisic acid negatively interferes with basal defence of barley against Magnaporthe oryzae.

Ulferts S, Delventhal R, Splivallo R, Karlovsky P, Schaffrath U - BMC Plant Biol. (2015)

Bottom Line: Interestingly, endogenous ABA concentrations did not significantly change after infection of barley with M. oryzae.Our results revealed that elevated ABA levels led to a higher disease severity on barley leaves to M. oryzae.This supports earlier reports on the role of ABA in enhancing susceptibility of rice to the same pathogen and thereby demonstrates a host plant-independent function of this phytohormone in pathogenicity of monocotyledonous plants against M. oryzae.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Physiology, RWTH Aachen University, 52056, Aachen, Germany. sylvia.ulferts@gmx.de.

ABSTRACT

Background: Plant hormones are well known regulators which balance plant responses to abiotic and biotic stresses. We investigated the role of abscisic acid (ABA) in resistance of barley (Hordeum vulgare L.) against the plant pathogenic fungus Magnaporthe oryzae.

Results: Exogenous application of ABA prior to inoculation with M. oryzae led to more disease symptoms on barley leaves. This result contrasted the finding that ABA application enhances resistance of barley against the powdery mildew fungus. Microscopic analysis identified diminished penetration resistance as cause for enhanced susceptibility. Consistently, the barley mutant Az34, impaired in ABA biosynthesis, was less susceptible to infection by M. oryzae and displayed elevated penetration resistance as compared to the isogenic wild type cultivar Steptoe. Chemical complementation of Az34 mutant plants by exogenous application of ABA re-established disease severity to the wild type level. The role of ABA in susceptibility of barley against M. oryzae was corroborated by showing that ABA application led to increased disease severity in all barley cultivars under investigation except for the most susceptible cultivar Pallas. Interestingly, endogenous ABA concentrations did not significantly change after infection of barley with M. oryzae.

Conclusion: Our results revealed that elevated ABA levels led to a higher disease severity on barley leaves to M. oryzae. This supports earlier reports on the role of ABA in enhancing susceptibility of rice to the same pathogen and thereby demonstrates a host plant-independent function of this phytohormone in pathogenicity of monocotyledonous plants against M. oryzae.

No MeSH data available.


Related in: MedlinePlus

Abscisic acid and salicylic acid level in different barley genotypes. Seven-day-old primary barley leaves were harvested from cultivar Ingrid, Himalaya, Steptoe, the backcross line BCIngridmlo5, and the mutant Az34, respectively. Samples consisting of five leaves were analysed by HPLC-MS-MS for ABA (A) or SA (B) content. Means and standard deviations for three samples harvested in a single experiment are shown. The experiment was repeated twice for ABA and once for SA determination with similar results.
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Fig7: Abscisic acid and salicylic acid level in different barley genotypes. Seven-day-old primary barley leaves were harvested from cultivar Ingrid, Himalaya, Steptoe, the backcross line BCIngridmlo5, and the mutant Az34, respectively. Samples consisting of five leaves were analysed by HPLC-MS-MS for ABA (A) or SA (B) content. Means and standard deviations for three samples harvested in a single experiment are shown. The experiment was repeated twice for ABA and once for SA determination with similar results.

Mentions: We verified our finding that the reduced ABA-content in Az34 mutant plants was the cause for a lower degree of susceptibility against M. oryzae by chemical complementation. Therefore mutant plants were sprayed with a 20 μM solution of ABA prior to inoculation. Indeed, exogenous application of ABA slightly but significantly increased the number of lesions on Az34 mutant plants to a level as observed on wild type plants (Figure 6). Interestingly, the number of disease symptoms on chemically complemented Az34 mutant plants was still lower than observed for ABA-treated Steptoe wild type plants. Endogenous ABA-levels were 3.2 ng per g fresh weight for the cultivar Steptoe and approximately half of that for the Az34 mutant (Figure 7), indicating that ABA-biosynthesis was compromised rather than completely abolished in the mutant.Figure 6


Abscisic acid negatively interferes with basal defence of barley against Magnaporthe oryzae.

Ulferts S, Delventhal R, Splivallo R, Karlovsky P, Schaffrath U - BMC Plant Biol. (2015)

Abscisic acid and salicylic acid level in different barley genotypes. Seven-day-old primary barley leaves were harvested from cultivar Ingrid, Himalaya, Steptoe, the backcross line BCIngridmlo5, and the mutant Az34, respectively. Samples consisting of five leaves were analysed by HPLC-MS-MS for ABA (A) or SA (B) content. Means and standard deviations for three samples harvested in a single experiment are shown. The experiment was repeated twice for ABA and once for SA determination with similar results.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307682&req=5

Fig7: Abscisic acid and salicylic acid level in different barley genotypes. Seven-day-old primary barley leaves were harvested from cultivar Ingrid, Himalaya, Steptoe, the backcross line BCIngridmlo5, and the mutant Az34, respectively. Samples consisting of five leaves were analysed by HPLC-MS-MS for ABA (A) or SA (B) content. Means and standard deviations for three samples harvested in a single experiment are shown. The experiment was repeated twice for ABA and once for SA determination with similar results.
Mentions: We verified our finding that the reduced ABA-content in Az34 mutant plants was the cause for a lower degree of susceptibility against M. oryzae by chemical complementation. Therefore mutant plants were sprayed with a 20 μM solution of ABA prior to inoculation. Indeed, exogenous application of ABA slightly but significantly increased the number of lesions on Az34 mutant plants to a level as observed on wild type plants (Figure 6). Interestingly, the number of disease symptoms on chemically complemented Az34 mutant plants was still lower than observed for ABA-treated Steptoe wild type plants. Endogenous ABA-levels were 3.2 ng per g fresh weight for the cultivar Steptoe and approximately half of that for the Az34 mutant (Figure 7), indicating that ABA-biosynthesis was compromised rather than completely abolished in the mutant.Figure 6

Bottom Line: Interestingly, endogenous ABA concentrations did not significantly change after infection of barley with M. oryzae.Our results revealed that elevated ABA levels led to a higher disease severity on barley leaves to M. oryzae.This supports earlier reports on the role of ABA in enhancing susceptibility of rice to the same pathogen and thereby demonstrates a host plant-independent function of this phytohormone in pathogenicity of monocotyledonous plants against M. oryzae.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Physiology, RWTH Aachen University, 52056, Aachen, Germany. sylvia.ulferts@gmx.de.

ABSTRACT

Background: Plant hormones are well known regulators which balance plant responses to abiotic and biotic stresses. We investigated the role of abscisic acid (ABA) in resistance of barley (Hordeum vulgare L.) against the plant pathogenic fungus Magnaporthe oryzae.

Results: Exogenous application of ABA prior to inoculation with M. oryzae led to more disease symptoms on barley leaves. This result contrasted the finding that ABA application enhances resistance of barley against the powdery mildew fungus. Microscopic analysis identified diminished penetration resistance as cause for enhanced susceptibility. Consistently, the barley mutant Az34, impaired in ABA biosynthesis, was less susceptible to infection by M. oryzae and displayed elevated penetration resistance as compared to the isogenic wild type cultivar Steptoe. Chemical complementation of Az34 mutant plants by exogenous application of ABA re-established disease severity to the wild type level. The role of ABA in susceptibility of barley against M. oryzae was corroborated by showing that ABA application led to increased disease severity in all barley cultivars under investigation except for the most susceptible cultivar Pallas. Interestingly, endogenous ABA concentrations did not significantly change after infection of barley with M. oryzae.

Conclusion: Our results revealed that elevated ABA levels led to a higher disease severity on barley leaves to M. oryzae. This supports earlier reports on the role of ABA in enhancing susceptibility of rice to the same pathogen and thereby demonstrates a host plant-independent function of this phytohormone in pathogenicity of monocotyledonous plants against M. oryzae.

No MeSH data available.


Related in: MedlinePlus