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Co-silencing of tomato S-adenosylhomocysteine hydrolase genes confers increased immunity against Pseudomonas syringae pv. tomato DC3000 and enhanced tolerance to drought stress.

Li X, Huang L, Hong Y, Zhang Y, Liu S, Li D, Zhang H, Song F - Front Plant Sci (2015)

Bottom Line: Virus-induced gene silencing-based knockdown of individual SlSAHH gene did not affect the growth performance and the response to Pst DC3000.The SlSAHH-co-silenced plants displayed increased resistance to Pst DC3000 but did not alter the resistance to B. cinerea.Co-silencing of SlSAHHs resulted in constitutively activated defense responses including elevated SA level, upregulated expression of defense-related and PAMP-triggered immunity marker genes and increased callose deposition and H2O2 accumulation.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University Hangzhou, China.

ABSTRACT
S-adenosylhomocysteine hydrolase (SAHH), catalyzing the reversible hydrolysis of S-adenosylhomocysteine (SAH) to adenosine and homocysteine, is a key enzyme that maintain the cellular methylation potential in all organisms. We report here the biological functions of tomato SlSAHHs in stress response. The tomato genome contains three SlSAHH genes that encode SlSAHH proteins with high level of sequence identity. qRT-PCR analysis revealed that SlSAHHs responded with distinct expression induction patterns to Pseudomonas syringae pv. tomato (Pst) DC3000 and Botrytis cinerea as well as to defense signaling hormones such as salicylic acid, jasmonic acid and a precursor of ethylene. Virus-induced gene silencing-based knockdown of individual SlSAHH gene did not affect the growth performance and the response to Pst DC3000. However, co-silencing of three SlSAHH genes using a conserved sequence led to significant inhibition of vegetable growth. The SlSAHH-co-silenced plants displayed increased resistance to Pst DC3000 but did not alter the resistance to B. cinerea. Co-silencing of SlSAHHs resulted in constitutively activated defense responses including elevated SA level, upregulated expression of defense-related and PAMP-triggered immunity marker genes and increased callose deposition and H2O2 accumulation. Furthermore, the SlSAHH-co-silenced plants also exhibited enhanced drought stress tolerance although they had relatively small roots. These data demonstrate that, in addition to the functions in growth and development, SAHHs also play important roles in regulating biotic and abiotic stress responses in plants.

No MeSH data available.


Related in: MedlinePlus

Expression patterns of SlSAHHs in response to pathogens and defense hormones. Four-week old plants were inoculated by vacuum infiltration with Pseudomonas syringae pv. tomato DC3000 (OD600 = 0.0002) (A), foliar spraying with spore suspension (2 × 105 spores/mL) of B. cinerea(B) or with similar volumes of the same solution as mock-inoculation controls. Four-week-old plants were treated by foliar spraying with 100 μM SA, 100 μM MeJA, 100 μM ACC or solution as a control (C). Leaf samples were collected at indicated time points after inoculation or treatment. Expression data were normalized with the value of reference Actin gene and relative expression levels were shown as folds of the Actin expression level. Data presented are the means ± SD from three independent experiments and ∗ above the columns indicate significant differences at p < 0.05 level between the pathogen-inoculated or hormone-treated plants and the mock-inoculated/treated plants.
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Figure 1: Expression patterns of SlSAHHs in response to pathogens and defense hormones. Four-week old plants were inoculated by vacuum infiltration with Pseudomonas syringae pv. tomato DC3000 (OD600 = 0.0002) (A), foliar spraying with spore suspension (2 × 105 spores/mL) of B. cinerea(B) or with similar volumes of the same solution as mock-inoculation controls. Four-week-old plants were treated by foliar spraying with 100 μM SA, 100 μM MeJA, 100 μM ACC or solution as a control (C). Leaf samples were collected at indicated time points after inoculation or treatment. Expression data were normalized with the value of reference Actin gene and relative expression levels were shown as folds of the Actin expression level. Data presented are the means ± SD from three independent experiments and ∗ above the columns indicate significant differences at p < 0.05 level between the pathogen-inoculated or hormone-treated plants and the mock-inoculated/treated plants.

Mentions: To explore the possible role of SlSAHHs in disease resistance, we analyzed the expression changes of SlSAHHs in response to infection by Pst DC3000 and B. cinerea as well as to treatments with three well-known defense signaling hormones such as SA, JA and ACC (a precursor or ET). In Pst DC3000-inoculated plants, the expression level of SlSAHH1 was decreased significantly at 24 h after inoculation, whereas the expression of SlSAHH2 and SlSAHH3 was not affected (Figure 1A). By contrast, the expression of SlSAHH2 and SlSAHH3 in B. cinerea-inoculated plants were markedly induced, leading to 4.4 and 1.6 folds of increases over those in mock-inoculated control plants, respectively; however, the expression of SlSAHH1 was not changed (Figure 1B). Meanwhile, we also analyzed the expression changes of SlSAHHs in response to different defense signaling hormones. As shown in Figure 1C, the expression of SlSAHH1 and SlSAHH3 was induced by SA at 6 h after treatment, but the expression of SlSAHH2 was not affected. The expression of SlSAHH1 and SlSAHH2 was induced by JA and ACC at 6 h after treatment, but the expression of SlSAHH3 was not affected (Figure 1C). These data indicate that SlSAHHs respond with distinct expression induction patterns to different pathogens and defense signaling hormones, suggesting possible involvements of SlSAHHs in defense response of tomato plants against pathogen infection.


Co-silencing of tomato S-adenosylhomocysteine hydrolase genes confers increased immunity against Pseudomonas syringae pv. tomato DC3000 and enhanced tolerance to drought stress.

Li X, Huang L, Hong Y, Zhang Y, Liu S, Li D, Zhang H, Song F - Front Plant Sci (2015)

Expression patterns of SlSAHHs in response to pathogens and defense hormones. Four-week old plants were inoculated by vacuum infiltration with Pseudomonas syringae pv. tomato DC3000 (OD600 = 0.0002) (A), foliar spraying with spore suspension (2 × 105 spores/mL) of B. cinerea(B) or with similar volumes of the same solution as mock-inoculation controls. Four-week-old plants were treated by foliar spraying with 100 μM SA, 100 μM MeJA, 100 μM ACC or solution as a control (C). Leaf samples were collected at indicated time points after inoculation or treatment. Expression data were normalized with the value of reference Actin gene and relative expression levels were shown as folds of the Actin expression level. Data presented are the means ± SD from three independent experiments and ∗ above the columns indicate significant differences at p < 0.05 level between the pathogen-inoculated or hormone-treated plants and the mock-inoculated/treated plants.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561804&req=5

Figure 1: Expression patterns of SlSAHHs in response to pathogens and defense hormones. Four-week old plants were inoculated by vacuum infiltration with Pseudomonas syringae pv. tomato DC3000 (OD600 = 0.0002) (A), foliar spraying with spore suspension (2 × 105 spores/mL) of B. cinerea(B) or with similar volumes of the same solution as mock-inoculation controls. Four-week-old plants were treated by foliar spraying with 100 μM SA, 100 μM MeJA, 100 μM ACC or solution as a control (C). Leaf samples were collected at indicated time points after inoculation or treatment. Expression data were normalized with the value of reference Actin gene and relative expression levels were shown as folds of the Actin expression level. Data presented are the means ± SD from three independent experiments and ∗ above the columns indicate significant differences at p < 0.05 level between the pathogen-inoculated or hormone-treated plants and the mock-inoculated/treated plants.
Mentions: To explore the possible role of SlSAHHs in disease resistance, we analyzed the expression changes of SlSAHHs in response to infection by Pst DC3000 and B. cinerea as well as to treatments with three well-known defense signaling hormones such as SA, JA and ACC (a precursor or ET). In Pst DC3000-inoculated plants, the expression level of SlSAHH1 was decreased significantly at 24 h after inoculation, whereas the expression of SlSAHH2 and SlSAHH3 was not affected (Figure 1A). By contrast, the expression of SlSAHH2 and SlSAHH3 in B. cinerea-inoculated plants were markedly induced, leading to 4.4 and 1.6 folds of increases over those in mock-inoculated control plants, respectively; however, the expression of SlSAHH1 was not changed (Figure 1B). Meanwhile, we also analyzed the expression changes of SlSAHHs in response to different defense signaling hormones. As shown in Figure 1C, the expression of SlSAHH1 and SlSAHH3 was induced by SA at 6 h after treatment, but the expression of SlSAHH2 was not affected. The expression of SlSAHH1 and SlSAHH2 was induced by JA and ACC at 6 h after treatment, but the expression of SlSAHH3 was not affected (Figure 1C). These data indicate that SlSAHHs respond with distinct expression induction patterns to different pathogens and defense signaling hormones, suggesting possible involvements of SlSAHHs in defense response of tomato plants against pathogen infection.

Bottom Line: Virus-induced gene silencing-based knockdown of individual SlSAHH gene did not affect the growth performance and the response to Pst DC3000.The SlSAHH-co-silenced plants displayed increased resistance to Pst DC3000 but did not alter the resistance to B. cinerea.Co-silencing of SlSAHHs resulted in constitutively activated defense responses including elevated SA level, upregulated expression of defense-related and PAMP-triggered immunity marker genes and increased callose deposition and H2O2 accumulation.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University Hangzhou, China.

ABSTRACT
S-adenosylhomocysteine hydrolase (SAHH), catalyzing the reversible hydrolysis of S-adenosylhomocysteine (SAH) to adenosine and homocysteine, is a key enzyme that maintain the cellular methylation potential in all organisms. We report here the biological functions of tomato SlSAHHs in stress response. The tomato genome contains three SlSAHH genes that encode SlSAHH proteins with high level of sequence identity. qRT-PCR analysis revealed that SlSAHHs responded with distinct expression induction patterns to Pseudomonas syringae pv. tomato (Pst) DC3000 and Botrytis cinerea as well as to defense signaling hormones such as salicylic acid, jasmonic acid and a precursor of ethylene. Virus-induced gene silencing-based knockdown of individual SlSAHH gene did not affect the growth performance and the response to Pst DC3000. However, co-silencing of three SlSAHH genes using a conserved sequence led to significant inhibition of vegetable growth. The SlSAHH-co-silenced plants displayed increased resistance to Pst DC3000 but did not alter the resistance to B. cinerea. Co-silencing of SlSAHHs resulted in constitutively activated defense responses including elevated SA level, upregulated expression of defense-related and PAMP-triggered immunity marker genes and increased callose deposition and H2O2 accumulation. Furthermore, the SlSAHH-co-silenced plants also exhibited enhanced drought stress tolerance although they had relatively small roots. These data demonstrate that, in addition to the functions in growth and development, SAHHs also play important roles in regulating biotic and abiotic stress responses in plants.

No MeSH data available.


Related in: MedlinePlus