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Exocarp Properties and Transcriptomic Analysis of Cucumber (Cucumis sativus) Fruit Expressing Age-Related Resistance to Phytophthora capsici.

Ando K, Carr KM, Colle M, Mansfeld BN, Grumet R - PLoS ONE (2015)

Bottom Line: The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown.Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions.Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways.

View Article: PubMed Central - PubMed

Affiliation: Program in Plant Breeding, Genetics and Biotechnology, Michigan State University, East Lansing, MI, 48824, United States of America.

ABSTRACT
Very young cucumber (Cucumis sativus) fruit are highly susceptible to infection by the oomycete pathogen, Phytophthora capsici. As the fruit complete exponential growth, at approximately 10-12 days post pollination (dpp), they transition to resistance. The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown. Peel sections from cucumber fruit harvested at 8 dpp (susceptible) and 16 dpp (resistant) showed equivalent responses to inoculation as did whole fruit, indicating that the fruit surface plays an important role in defense against P. capsici. Exocarp from 16 dpp fruit had thicker cuticles, and methanolic extracts of peel tissue inhibited growth of P. capsici in vitro, suggesting physical or chemical components to the ARR. Transcripts specifically expressed in the peel vs. pericarp showed functional differentiation. Transcripts predominantly expressed in the peel were consistent with fruit surface associated functions including photosynthesis, cuticle production, response to the environment, and defense. Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions. Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways. The developmentally regulated changes in gene expression between peels from susceptible- and resistant- age fruits suggest programming for increased defense as the organ reaches full size.

No MeSH data available.


Related in: MedlinePlus

Expression analysis of putative defense related genes.(A) qRT-PCR verification of potential pathogen defense-related genes with elevated expression in 16 days post pollination (dpp) peels. (B) Relative expression of SYP121/SNAP33 co-expressed genes in 8 and 16 dpp pericarp and peel samples as assessed by 454 pyrosequencing. Genes shown are in the order listed in Table 4. (C) Expression of CsFM01 as assessed by 454 pyrosequencing (left) and qRT-PCR analysis (right). 8 = 8 dpp pericarp; 8p = 8 dpp peel; 16 = 16 dpp pericarp; 16p = 16 dpp peel.
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pone.0142133.g004: Expression analysis of putative defense related genes.(A) qRT-PCR verification of potential pathogen defense-related genes with elevated expression in 16 days post pollination (dpp) peels. (B) Relative expression of SYP121/SNAP33 co-expressed genes in 8 and 16 dpp pericarp and peel samples as assessed by 454 pyrosequencing. Genes shown are in the order listed in Table 4. (C) Expression of CsFM01 as assessed by 454 pyrosequencing (left) and qRT-PCR analysis (right). 8 = 8 dpp pericarp; 8p = 8 dpp peel; 16 = 16 dpp pericarp; 16p = 16 dpp peel.

Mentions: Greater than 40% of the 16 dpp peel-enriched genes were potentially associated with pathogen defense based on annotations from other systems (Table 3). A subset of 20 putative defense-related genes whose transcriptome patterns showed elevated expression in 16 dpp peel samples was selected for verification of expression by qRT-PCR analysis of pericarp and peel samples from 8 dpp and 16 dpp fruit (Fig 4A). The qRT-PCR results mirrored those of the 454 analysis, substantiating the 454 analysis, and also demonstrating reproducibility of gene expression patterns across experiments grown at different times in the greenhouse. Predominant expression was observed in 16 dpp peel tissue, although for a few genes (EDS1, NUDT7, SYP121), the difference between 8 dpp peel and 16 dpp peel was less pronounced in the qRT-PCR analysis than from the transcriptome data.


Exocarp Properties and Transcriptomic Analysis of Cucumber (Cucumis sativus) Fruit Expressing Age-Related Resistance to Phytophthora capsici.

Ando K, Carr KM, Colle M, Mansfeld BN, Grumet R - PLoS ONE (2015)

Expression analysis of putative defense related genes.(A) qRT-PCR verification of potential pathogen defense-related genes with elevated expression in 16 days post pollination (dpp) peels. (B) Relative expression of SYP121/SNAP33 co-expressed genes in 8 and 16 dpp pericarp and peel samples as assessed by 454 pyrosequencing. Genes shown are in the order listed in Table 4. (C) Expression of CsFM01 as assessed by 454 pyrosequencing (left) and qRT-PCR analysis (right). 8 = 8 dpp pericarp; 8p = 8 dpp peel; 16 = 16 dpp pericarp; 16p = 16 dpp peel.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4631441&req=5

pone.0142133.g004: Expression analysis of putative defense related genes.(A) qRT-PCR verification of potential pathogen defense-related genes with elevated expression in 16 days post pollination (dpp) peels. (B) Relative expression of SYP121/SNAP33 co-expressed genes in 8 and 16 dpp pericarp and peel samples as assessed by 454 pyrosequencing. Genes shown are in the order listed in Table 4. (C) Expression of CsFM01 as assessed by 454 pyrosequencing (left) and qRT-PCR analysis (right). 8 = 8 dpp pericarp; 8p = 8 dpp peel; 16 = 16 dpp pericarp; 16p = 16 dpp peel.
Mentions: Greater than 40% of the 16 dpp peel-enriched genes were potentially associated with pathogen defense based on annotations from other systems (Table 3). A subset of 20 putative defense-related genes whose transcriptome patterns showed elevated expression in 16 dpp peel samples was selected for verification of expression by qRT-PCR analysis of pericarp and peel samples from 8 dpp and 16 dpp fruit (Fig 4A). The qRT-PCR results mirrored those of the 454 analysis, substantiating the 454 analysis, and also demonstrating reproducibility of gene expression patterns across experiments grown at different times in the greenhouse. Predominant expression was observed in 16 dpp peel tissue, although for a few genes (EDS1, NUDT7, SYP121), the difference between 8 dpp peel and 16 dpp peel was less pronounced in the qRT-PCR analysis than from the transcriptome data.

Bottom Line: The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown.Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions.Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways.

View Article: PubMed Central - PubMed

Affiliation: Program in Plant Breeding, Genetics and Biotechnology, Michigan State University, East Lansing, MI, 48824, United States of America.

ABSTRACT
Very young cucumber (Cucumis sativus) fruit are highly susceptible to infection by the oomycete pathogen, Phytophthora capsici. As the fruit complete exponential growth, at approximately 10-12 days post pollination (dpp), they transition to resistance. The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown. Peel sections from cucumber fruit harvested at 8 dpp (susceptible) and 16 dpp (resistant) showed equivalent responses to inoculation as did whole fruit, indicating that the fruit surface plays an important role in defense against P. capsici. Exocarp from 16 dpp fruit had thicker cuticles, and methanolic extracts of peel tissue inhibited growth of P. capsici in vitro, suggesting physical or chemical components to the ARR. Transcripts specifically expressed in the peel vs. pericarp showed functional differentiation. Transcripts predominantly expressed in the peel were consistent with fruit surface associated functions including photosynthesis, cuticle production, response to the environment, and defense. Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions. Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways. The developmentally regulated changes in gene expression between peels from susceptible- and resistant- age fruits suggest programming for increased defense as the organ reaches full size.

No MeSH data available.


Related in: MedlinePlus