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Systemic Resistance to Powdery Mildew in Brassica napus (AACC) and Raphanus alboglabra (RRCC) by Trichoderma harzianum TH12.

Alkooranee JT, Yin Y, Aledan TR, Jiang Y, Lu G, Wu J, Li M - PLoS ONE (2015)

Bottom Line: In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones.The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF.The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.

ABSTRACT
Trichoderma harzianum TH12 is a microbial pesticide for certain rapeseed diseases. The mechanism of systemic resistance induced by TH12 or its cell-free culture filtrate (CF) in Brassica napus (AACC) and Raphanus alboglabra (RRCC) to powdery mildew disease caused by ascomycete Erysiphe cruciferarum was investigated. In this study, we conducted the first large-scale global study on the cellular and molecular aspects of B. napus and R. alboglabra infected with E. cruciferarum. The histological study showed the resistance of R. alboglabra to powdery mildew disease. The growth of fungal colonies was not observed on R. alboglabra leaves at 1, 2, 4, 6, 8, and 10 days post-inoculation (dpi), whereas this was clearly observed on B. napus leaves after 6 dpi. In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones. The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF. The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum. However, expression levels increased when the leaves were treated with TH12. For the first time, we disclosed the nature of gene expression in B. napus and R. alboglabra to explore the resistance pathways in the leaves of both genotypes infected and non-infected by powdery mildew and inoculated or non-inoculated with elicitor factors. Results suggested that R. alboglabra exhibited resistance to powdery mildew disease, and the application of T. harzianum and its CF are a useful tool to facilitate new protection methods for resist or susceptible plants.

No MeSH data available.


Symptoms of Erysiphe cruciferarum on leaves infected of B. napus of 6 time points.Symptom images were (a1, b1, c1, d1, e1, f1) and light micrograph were (a, b, c, d, e, f) for leaves of R. alboglabra infected by pathogen were (g1, h1, i1, j1, k1, l1) and light micrograph were (g, h, i, j, k, l) for leaves of RRCC infected by pathogen at 1, 2, 4, 6, 8 and 10 days post-inoculation (dpi) respectively. Stocks indicate to colonies and the growth of pathogenic fungus. Scale bars for light micrograph at 8 and 10 dpi are 25 μm.
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pone.0142177.g003: Symptoms of Erysiphe cruciferarum on leaves infected of B. napus of 6 time points.Symptom images were (a1, b1, c1, d1, e1, f1) and light micrograph were (a, b, c, d, e, f) for leaves of R. alboglabra infected by pathogen were (g1, h1, i1, j1, k1, l1) and light micrograph were (g, h, i, j, k, l) for leaves of RRCC infected by pathogen at 1, 2, 4, 6, 8 and 10 days post-inoculation (dpi) respectively. Stocks indicate to colonies and the growth of pathogenic fungus. Scale bars for light micrograph at 8 and 10 dpi are 25 μm.

Mentions: At 6 dpi, symptoms of infection were observed in white powdery mildew on the upper surface of B. napus leaves. Symptoms can be observed with the naked eye and increased with the progress of time (Fig 3D1, 3E1, and 3F1). The observable signs of the pathogen included hyphae, conidia, conidiophores, and dead cells on the infected leaf surface, whereas visual symptoms were not observed in the R. alboglabra genotype (Fig 3G1–3I1). At 1 dpi, the structures of pathogenic fungi appeared on the securities under microscopic examination, but lower compared with B. napus (Fig 3G). Microscopic examination showed the conidia of the pathogenic fungus produced germination tubes on the leaves of both genotypes, where conidia produced primary germ tube, aspersorium, and primary hyphae at 2 dpi, followed by hyphae in B. napus and to lesser extent in R. alboglabra (Fig 3B). The rapid growth and wide spread of the pathogen and hyphae were also observed. Several conidia were observed on the upper surface of the infected leaves of B. napus. The fungus growth increased with time (Fig 3C–3F). On the contrary, the microscopic examination on R. alboglabra showed that most of the conidia produced germination tubes, but failed to format the hyphae. These conidia did not develop intensively and rapidly compared with B. napus during the same time period (Fig 3I–3l). The results also showed the presence of dead cells in B. napus, and R. alboglabra increased. However, fungus growth was densely spread and increased with time. The microscopic examination clearly emerged after 6, 8, and 10 dpi (Fig 3F and 3I). The percentage of spores that successfully germinated on the leaf surface did not differ between the genotypes and time points. However, the further development of the fungus differed during cell penetration; development was lower for R. alboglabra (5%) compared with B. napus (75%) at 2 dpi. This continued penetration resistance reached 14% successful penetration at 4 dpi compared with 68% of B. napus (Fig 3G and 3H). Thus, no or very little colonies were formed on R. alboglabra at 4, 6, 8, and 10 dpi. Finally, the histological study confirmed that the R. alboglabra genotype was excluded from infection because it was able to prevent the pathogenic fungus E. cruciferarum from penetrating the cell wall of host successfully and inhibited the growth of the pathogen at different stages. This penetration resistance was activated at 1 dpi and allowed complete resistance under certain conditions.


Systemic Resistance to Powdery Mildew in Brassica napus (AACC) and Raphanus alboglabra (RRCC) by Trichoderma harzianum TH12.

Alkooranee JT, Yin Y, Aledan TR, Jiang Y, Lu G, Wu J, Li M - PLoS ONE (2015)

Symptoms of Erysiphe cruciferarum on leaves infected of B. napus of 6 time points.Symptom images were (a1, b1, c1, d1, e1, f1) and light micrograph were (a, b, c, d, e, f) for leaves of R. alboglabra infected by pathogen were (g1, h1, i1, j1, k1, l1) and light micrograph were (g, h, i, j, k, l) for leaves of RRCC infected by pathogen at 1, 2, 4, 6, 8 and 10 days post-inoculation (dpi) respectively. Stocks indicate to colonies and the growth of pathogenic fungus. Scale bars for light micrograph at 8 and 10 dpi are 25 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4634854&req=5

pone.0142177.g003: Symptoms of Erysiphe cruciferarum on leaves infected of B. napus of 6 time points.Symptom images were (a1, b1, c1, d1, e1, f1) and light micrograph were (a, b, c, d, e, f) for leaves of R. alboglabra infected by pathogen were (g1, h1, i1, j1, k1, l1) and light micrograph were (g, h, i, j, k, l) for leaves of RRCC infected by pathogen at 1, 2, 4, 6, 8 and 10 days post-inoculation (dpi) respectively. Stocks indicate to colonies and the growth of pathogenic fungus. Scale bars for light micrograph at 8 and 10 dpi are 25 μm.
Mentions: At 6 dpi, symptoms of infection were observed in white powdery mildew on the upper surface of B. napus leaves. Symptoms can be observed with the naked eye and increased with the progress of time (Fig 3D1, 3E1, and 3F1). The observable signs of the pathogen included hyphae, conidia, conidiophores, and dead cells on the infected leaf surface, whereas visual symptoms were not observed in the R. alboglabra genotype (Fig 3G1–3I1). At 1 dpi, the structures of pathogenic fungi appeared on the securities under microscopic examination, but lower compared with B. napus (Fig 3G). Microscopic examination showed the conidia of the pathogenic fungus produced germination tubes on the leaves of both genotypes, where conidia produced primary germ tube, aspersorium, and primary hyphae at 2 dpi, followed by hyphae in B. napus and to lesser extent in R. alboglabra (Fig 3B). The rapid growth and wide spread of the pathogen and hyphae were also observed. Several conidia were observed on the upper surface of the infected leaves of B. napus. The fungus growth increased with time (Fig 3C–3F). On the contrary, the microscopic examination on R. alboglabra showed that most of the conidia produced germination tubes, but failed to format the hyphae. These conidia did not develop intensively and rapidly compared with B. napus during the same time period (Fig 3I–3l). The results also showed the presence of dead cells in B. napus, and R. alboglabra increased. However, fungus growth was densely spread and increased with time. The microscopic examination clearly emerged after 6, 8, and 10 dpi (Fig 3F and 3I). The percentage of spores that successfully germinated on the leaf surface did not differ between the genotypes and time points. However, the further development of the fungus differed during cell penetration; development was lower for R. alboglabra (5%) compared with B. napus (75%) at 2 dpi. This continued penetration resistance reached 14% successful penetration at 4 dpi compared with 68% of B. napus (Fig 3G and 3H). Thus, no or very little colonies were formed on R. alboglabra at 4, 6, 8, and 10 dpi. Finally, the histological study confirmed that the R. alboglabra genotype was excluded from infection because it was able to prevent the pathogenic fungus E. cruciferarum from penetrating the cell wall of host successfully and inhibited the growth of the pathogen at different stages. This penetration resistance was activated at 1 dpi and allowed complete resistance under certain conditions.

Bottom Line: In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones.The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF.The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.

ABSTRACT
Trichoderma harzianum TH12 is a microbial pesticide for certain rapeseed diseases. The mechanism of systemic resistance induced by TH12 or its cell-free culture filtrate (CF) in Brassica napus (AACC) and Raphanus alboglabra (RRCC) to powdery mildew disease caused by ascomycete Erysiphe cruciferarum was investigated. In this study, we conducted the first large-scale global study on the cellular and molecular aspects of B. napus and R. alboglabra infected with E. cruciferarum. The histological study showed the resistance of R. alboglabra to powdery mildew disease. The growth of fungal colonies was not observed on R. alboglabra leaves at 1, 2, 4, 6, 8, and 10 days post-inoculation (dpi), whereas this was clearly observed on B. napus leaves after 6 dpi. In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones. The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF. The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum. However, expression levels increased when the leaves were treated with TH12. For the first time, we disclosed the nature of gene expression in B. napus and R. alboglabra to explore the resistance pathways in the leaves of both genotypes infected and non-infected by powdery mildew and inoculated or non-inoculated with elicitor factors. Results suggested that R. alboglabra exhibited resistance to powdery mildew disease, and the application of T. harzianum and its CF are a useful tool to facilitate new protection methods for resist or susceptible plants.

No MeSH data available.