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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

Co-silencing of SlSAHHs conferred an enhanced drought stress tolerance. Ten-day-old seedlings were infiltrated with agrobacteria carrying TRV-SlSAHHa or TRV-GUS construct and drought stress was applied to the plants by withholding water at 4 weeks after agroinfiltration. (A) Growth performance and drought phenotype of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. (B) Rates of water loss in detached leaves of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (C) Root system of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (D) Dry weight of roots from the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (E) Expression patterns of drought stress-related genes in TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. Similar results were obtained in independent experiments (A,C) and data presented in (B), (D), and (E) are the means ± SD from three independent experiments and ∗ above the columns in (B), (D), and (E) indicate significant differences at p < 0.05 level between the TRV-SlSAHHa- and TRV-GUS-infiltrated plants.
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Figure 6: Co-silencing of SlSAHHs conferred an enhanced drought stress tolerance. Ten-day-old seedlings were infiltrated with agrobacteria carrying TRV-SlSAHHa or TRV-GUS construct and drought stress was applied to the plants by withholding water at 4 weeks after agroinfiltration. (A) Growth performance and drought phenotype of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. (B) Rates of water loss in detached leaves of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (C) Root system of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (D) Dry weight of roots from the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (E) Expression patterns of drought stress-related genes in TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. Similar results were obtained in independent experiments (A,C) and data presented in (B), (D), and (E) are the means ± SD from three independent experiments and ∗ above the columns in (B), (D), and (E) indicate significant differences at p < 0.05 level between the TRV-SlSAHHa- and TRV-GUS-infiltrated plants.

Mentions: During our experiments toward on the functions of SlSAHHs in disease resistance, we occasionally noted that the TRV-SlSAHHa-infiltrated plants were not easier, as compared with the TRV-GUS-infiltrated plants, to appear wilting symptom when the plants were not watered during a 3-day period, indicating a possible role for SlSAHHs in drought stress tolerance. We thus examined whether SlSAHHs play a role in drought stress tolerance by analyzing and comparing the drought tolerance of the TRV-SlSAHHa- and TRV-GUS-infiltrated plants after withholding water for 2 weeks. As shown in Figure 6A, the growth status of the TRV-SlSAHHa- and TRV-GUS-infiltrated plants was similar before withholding water although the TRV-SlSAHHa-infiltrated plants were shorter than the TRV-GUS-infiltrated plants. At 2 weeks after withholding water, leaves of the TRV-GUS-infiltrated plants became curly and drooped and the plants wilted and eventually died; however, the TRV-SlSAHHa-infiltrated still grew well and showed normal appearance without any wilted leaves (Figure 6A). To confirm this observation, we analyzed the rate of water loss in detached leaves from the TRV-SlSAHHa- and TRV-GUS-infiltrated plants. The rate of water loss in leaves from the TRV-SlSAHHa-infiltrated plants was significantly decreased, leading to ∼30% of reduction, as compared with that in leaves from the TRV-GUS-infiltrated inoculated plants during a period of 3 h after detachment (Figure 6B). We also examined whether co-silencing of SlSAHHs affected the development of root system in tomato plants. Unexpectedly, the TRV-SlSAHHa-infiltrated plants had relatively small root system (Figure 6C) and the dry weight of the roots from the TRV-SlSAHHa-infiltrated plants was significantly decreased by 32% (Figure 6D), as compared with those of the TRV-GUS-infiltrated plants. We further examined and compared the expression patterns of some known drought stress-responsive genes in TRV-GUS- and TRV-SlSAHHa-infiltrated plants. In the TRV-SlSAHHa-infiltrated plants, the expression levels of SlAREB1 (abscisic acid-responsive element bingding protein 1), SlAREB2 (abscisic acid-responsive element bingding protein 2), SlDREB (dehydration-responsive element-binding protein), SlSpUSP and SGN-U213276, which are drought stress-upregulated genes (Gong et al., 2010; Orellana et al., 2010; Li et al., 2012; Loukehaich et al., 2012), were significantly increased by 4–7 folds for SlAREB1, SlDREB, SlSpUSP and SGN-U213276 and onefold for SlAREB2, while the expression level of SGN-U214777, a drought stress-downregulated gene (Gong et al., 2010), was decreased by threefolds, as compared with those in TRV-GUS-infiltrated plants (Figure 6E). These data indicate that co-silencing of SlSAHHs led to an increased drought stress tolerance in tomato.


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)

Co-silencing of SlSAHHs conferred an enhanced drought stress tolerance. Ten-day-old seedlings were infiltrated with agrobacteria carrying TRV-SlSAHHa or TRV-GUS construct and drought stress was applied to the plants by withholding water at 4 weeks after agroinfiltration. (A) Growth performance and drought phenotype of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. (B) Rates of water loss in detached leaves of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (C) Root system of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (D) Dry weight of roots from the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (E) Expression patterns of drought stress-related genes in TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. Similar results were obtained in independent experiments (A,C) and data presented in (B), (D), and (E) are the means ± SD from three independent experiments and ∗ above the columns in (B), (D), and (E) indicate significant differences at p < 0.05 level between the TRV-SlSAHHa- and TRV-GUS-infiltrated plants.
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Figure 6: Co-silencing of SlSAHHs conferred an enhanced drought stress tolerance. Ten-day-old seedlings were infiltrated with agrobacteria carrying TRV-SlSAHHa or TRV-GUS construct and drought stress was applied to the plants by withholding water at 4 weeks after agroinfiltration. (A) Growth performance and drought phenotype of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. (B) Rates of water loss in detached leaves of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (C) Root system of the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (D) Dry weight of roots from the TRV-GUS- and TRV-SlSAHHa-infiltrated plants. (E) Expression patterns of drought stress-related genes in TRV-GUS- and TRV-SlSAHHa-infiltrated plants before and after drought stress treatment. Similar results were obtained in independent experiments (A,C) and data presented in (B), (D), and (E) are the means ± SD from three independent experiments and ∗ above the columns in (B), (D), and (E) indicate significant differences at p < 0.05 level between the TRV-SlSAHHa- and TRV-GUS-infiltrated plants.
Mentions: During our experiments toward on the functions of SlSAHHs in disease resistance, we occasionally noted that the TRV-SlSAHHa-infiltrated plants were not easier, as compared with the TRV-GUS-infiltrated plants, to appear wilting symptom when the plants were not watered during a 3-day period, indicating a possible role for SlSAHHs in drought stress tolerance. We thus examined whether SlSAHHs play a role in drought stress tolerance by analyzing and comparing the drought tolerance of the TRV-SlSAHHa- and TRV-GUS-infiltrated plants after withholding water for 2 weeks. As shown in Figure 6A, the growth status of the TRV-SlSAHHa- and TRV-GUS-infiltrated plants was similar before withholding water although the TRV-SlSAHHa-infiltrated plants were shorter than the TRV-GUS-infiltrated plants. At 2 weeks after withholding water, leaves of the TRV-GUS-infiltrated plants became curly and drooped and the plants wilted and eventually died; however, the TRV-SlSAHHa-infiltrated still grew well and showed normal appearance without any wilted leaves (Figure 6A). To confirm this observation, we analyzed the rate of water loss in detached leaves from the TRV-SlSAHHa- and TRV-GUS-infiltrated plants. The rate of water loss in leaves from the TRV-SlSAHHa-infiltrated plants was significantly decreased, leading to ∼30% of reduction, as compared with that in leaves from the TRV-GUS-infiltrated inoculated plants during a period of 3 h after detachment (Figure 6B). We also examined whether co-silencing of SlSAHHs affected the development of root system in tomato plants. Unexpectedly, the TRV-SlSAHHa-infiltrated plants had relatively small root system (Figure 6C) and the dry weight of the roots from the TRV-SlSAHHa-infiltrated plants was significantly decreased by 32% (Figure 6D), as compared with those of the TRV-GUS-infiltrated plants. We further examined and compared the expression patterns of some known drought stress-responsive genes in TRV-GUS- and TRV-SlSAHHa-infiltrated plants. In the TRV-SlSAHHa-infiltrated plants, the expression levels of SlAREB1 (abscisic acid-responsive element bingding protein 1), SlAREB2 (abscisic acid-responsive element bingding protein 2), SlDREB (dehydration-responsive element-binding protein), SlSpUSP and SGN-U213276, which are drought stress-upregulated genes (Gong et al., 2010; Orellana et al., 2010; Li et al., 2012; Loukehaich et al., 2012), were significantly increased by 4–7 folds for SlAREB1, SlDREB, SlSpUSP and SGN-U213276 and onefold for SlAREB2, while the expression level of SGN-U214777, a drought stress-downregulated gene (Gong et al., 2010), was decreased by threefolds, as compared with those in TRV-GUS-infiltrated plants (Figure 6E). These data indicate that co-silencing of SlSAHHs led to an increased drought stress tolerance in tomato.

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