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Crosstalk between the circadian clock and innate immunity in Arabidopsis.

Zhang C, Xie Q, Anderson RG, Ng G, Seitz NC, Peterson T, McClung CR, McDowell JM, Kong D, Kwak JM, Lu H - PLoS Pathog. (2013)

Bottom Line: Recently, the circadian clock has been shown to affect plant responses to biotic cues.Furthermore, we found defense activation by P. syringae infection and treatment with the elicitor flg22 can feedback-regulate clock activity.Together this data strongly supports a direct role of the circadian clock in defense control and reveal for the first time crosstalk between the circadian clock and plant innate immunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, United States of America.

ABSTRACT
The circadian clock integrates temporal information with environmental cues in regulating plant development and physiology. Recently, the circadian clock has been shown to affect plant responses to biotic cues. To further examine this role of the circadian clock, we tested disease resistance in mutants disrupted in CCA1 and LHY, which act synergistically to regulate clock activity. We found that cca1 and lhy mutants also synergistically affect basal and resistance gene-mediated defense against Pseudomonas syringae and Hyaloperonospora arabidopsidis. Disrupting the circadian clock caused by overexpression of CCA1 or LHY also resulted in severe susceptibility to P. syringae. We identified a downstream target of CCA1 and LHY, GRP7, a key constituent of a slave oscillator regulated by the circadian clock and previously shown to influence plant defense and stomatal activity. We show that the defense role of CCA1 and LHY against P. syringae is at least partially through circadian control of stomatal aperture but is independent of defense mediated by salicylic acid. Furthermore, we found defense activation by P. syringae infection and treatment with the elicitor flg22 can feedback-regulate clock activity. Together this data strongly supports a direct role of the circadian clock in defense control and reveal for the first time crosstalk between the circadian clock and plant innate immunity.

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Related in: MedlinePlus

Bacterial growth in plants infiltrated with Pseudomonas syringae pv.maculicola strain DG3 (PmaDG3).(A) Time scheme used in this report. The white box indicates the light period and black boxes indicate dark periods. (B) ZT1 infection. (C) ZT13 infection. In 12 hr L/12 hr D (LD), 25-day-old plants were grown and infected by infiltration with PmaDG3 at 1×105 colony forming unit (CFU)/ml. Bacterial growth was assessed at 3 dpi. Data represent the average of bacterial numbers in six samples ± standard error. Log transformed bacterial growth was used in statistical analysis (Student's t-test). Letters indicate significant difference among the samples (P<0.05). These experiments were repeated three times with similar results.
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ppat-1003370-g002: Bacterial growth in plants infiltrated with Pseudomonas syringae pv.maculicola strain DG3 (PmaDG3).(A) Time scheme used in this report. The white box indicates the light period and black boxes indicate dark periods. (B) ZT1 infection. (C) ZT13 infection. In 12 hr L/12 hr D (LD), 25-day-old plants were grown and infected by infiltration with PmaDG3 at 1×105 colony forming unit (CFU)/ml. Bacterial growth was assessed at 3 dpi. Data represent the average of bacterial numbers in six samples ± standard error. Log transformed bacterial growth was used in statistical analysis (Student's t-test). Letters indicate significant difference among the samples (P<0.05). These experiments were repeated three times with similar results.

Mentions: To test disease resistance of cca1-1 and lhy-20 plants, we performed infection experiments at Zeitgeber Time 1 (Zeitgeber Time is the time relative to dawn; ZT1 is 1 hr after lights on) or ZT13 (1 hr after lights off), two times of day associated with drastic changes of light regime. Plant leaves were pressure-infiltrated with virulent P. syringae pv. maculicola ES4326 strain DG3 (PmaDG3) [36]. The infected plants were placed in either LD or LL. Bacterial growth assays at 3 days post infection (3 dpi) revealed no significant difference among Col-0, cca1-1, lhy-20, and cca1-1lhy-20 in either LD or LL (Figure 2 and Figure S2).


Crosstalk between the circadian clock and innate immunity in Arabidopsis.

Zhang C, Xie Q, Anderson RG, Ng G, Seitz NC, Peterson T, McClung CR, McDowell JM, Kong D, Kwak JM, Lu H - PLoS Pathog. (2013)

Bacterial growth in plants infiltrated with Pseudomonas syringae pv.maculicola strain DG3 (PmaDG3).(A) Time scheme used in this report. The white box indicates the light period and black boxes indicate dark periods. (B) ZT1 infection. (C) ZT13 infection. In 12 hr L/12 hr D (LD), 25-day-old plants were grown and infected by infiltration with PmaDG3 at 1×105 colony forming unit (CFU)/ml. Bacterial growth was assessed at 3 dpi. Data represent the average of bacterial numbers in six samples ± standard error. Log transformed bacterial growth was used in statistical analysis (Student's t-test). Letters indicate significant difference among the samples (P<0.05). These experiments were repeated three times with similar results.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675028&req=5

ppat-1003370-g002: Bacterial growth in plants infiltrated with Pseudomonas syringae pv.maculicola strain DG3 (PmaDG3).(A) Time scheme used in this report. The white box indicates the light period and black boxes indicate dark periods. (B) ZT1 infection. (C) ZT13 infection. In 12 hr L/12 hr D (LD), 25-day-old plants were grown and infected by infiltration with PmaDG3 at 1×105 colony forming unit (CFU)/ml. Bacterial growth was assessed at 3 dpi. Data represent the average of bacterial numbers in six samples ± standard error. Log transformed bacterial growth was used in statistical analysis (Student's t-test). Letters indicate significant difference among the samples (P<0.05). These experiments were repeated three times with similar results.
Mentions: To test disease resistance of cca1-1 and lhy-20 plants, we performed infection experiments at Zeitgeber Time 1 (Zeitgeber Time is the time relative to dawn; ZT1 is 1 hr after lights on) or ZT13 (1 hr after lights off), two times of day associated with drastic changes of light regime. Plant leaves were pressure-infiltrated with virulent P. syringae pv. maculicola ES4326 strain DG3 (PmaDG3) [36]. The infected plants were placed in either LD or LL. Bacterial growth assays at 3 days post infection (3 dpi) revealed no significant difference among Col-0, cca1-1, lhy-20, and cca1-1lhy-20 in either LD or LL (Figure 2 and Figure S2).

Bottom Line: Recently, the circadian clock has been shown to affect plant responses to biotic cues.Furthermore, we found defense activation by P. syringae infection and treatment with the elicitor flg22 can feedback-regulate clock activity.Together this data strongly supports a direct role of the circadian clock in defense control and reveal for the first time crosstalk between the circadian clock and plant innate immunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, United States of America.

ABSTRACT
The circadian clock integrates temporal information with environmental cues in regulating plant development and physiology. Recently, the circadian clock has been shown to affect plant responses to biotic cues. To further examine this role of the circadian clock, we tested disease resistance in mutants disrupted in CCA1 and LHY, which act synergistically to regulate clock activity. We found that cca1 and lhy mutants also synergistically affect basal and resistance gene-mediated defense against Pseudomonas syringae and Hyaloperonospora arabidopsidis. Disrupting the circadian clock caused by overexpression of CCA1 or LHY also resulted in severe susceptibility to P. syringae. We identified a downstream target of CCA1 and LHY, GRP7, a key constituent of a slave oscillator regulated by the circadian clock and previously shown to influence plant defense and stomatal activity. We show that the defense role of CCA1 and LHY against P. syringae is at least partially through circadian control of stomatal aperture but is independent of defense mediated by salicylic acid. Furthermore, we found defense activation by P. syringae infection and treatment with the elicitor flg22 can feedback-regulate clock activity. Together this data strongly supports a direct role of the circadian clock in defense control and reveal for the first time crosstalk between the circadian clock and plant innate immunity.

Show MeSH
Related in: MedlinePlus