Comparison of “priming” and “synergy”.

<p>(A, B) ROS generation and defense gene expression induced by simultaneous treatment with LPS and GN8, or LPS pretreatment (-120 min) and successive GN8 treatment (0 min). LPS concentration was 0.1 µg/ml and GN8 concentration was 0.08 ng/ml. (C, D) Changes in JA and JA-Ile concentration after simultaneous treatment with LPS (0.1 µg/ml) and GN8 (0.08 ng/ml). Synergistic effect was observed for the accumulation of JA but not for JA-Ile. Experimental conditions were the same to Fig. 1.</p

Synergistic enhancement of defense responses by different combination of MAMPs.

<p>(A) Synergistic induction of ROS generation by simultaneous treatment of LPS (0.1 µg/ml) and flg22 (1 ng/ml). (B) Synergistic induction of ROS generation by simultaneous treatment of GN8 (0.08 ng/ml) and flg22 (1 ng/ml). (C) Synergistic induction of defense gene expression by LPS:flg22 or GN8:flg22. (D) Comparison of ROS generation induced by simultaneous treatment with two or three MAMP elicitors. Experimental conditions were the same to Fig. 1.</p

Synergistic effect on ROS generation in rice seedlings.

<p>(A) For priming experiments, LPS (5 µg/ml) was pretreated for 120 min before <i>N-Acetylechitoheptaose</i> (GN7, 10 ng/ml = 6.9 nM) treatment. In the case of simultaneous treatment, both LPS and GN7 were added simultaneously. The increment of ROS in 20 min after GN7 treatment was used as the index of defense response. (B) ROS generation induced by simultaneous treatment of GN7 (10 ng/ml) and flg22 (10 ng/ml = 4.4 nM).</p

LPS pretreatment primed chitin-induced defense responses in rice cells.

<p>(A) Priming of GN8-induced ROS generation by the pretreatment with <i>P. aeruginosa</i> LPS. (B) Priming of GN8-induced expression of defense related genes by the pretreatment with <i>P. aeruginosa</i> LPS. Relative expression to the water control was shown. <i>RCC1</i> (AK061042), rice class 1 chitinase; <i>rBG</i> (AK058891), rice β 1,3-glucanase; <i>OsDTC2</i> (AK108710), stemar-13-ene synthase; <i>OsKSL4</i> (AK119327), 9βH-pimara-7,15-diene synthase; <i>PAL</i> (AK068993), phenylalanine anmonia lyase. (C) Confirmation of LPS as the active component for priming activity. Commercial <i>P. aeruginosa</i> LPS preparation was applied to either a polymixin B-agarose column or a sepharose CL-6B column, and eluted with distilled water. Priming activity in the commercial LPS preparation was completely recovered in the flow-through fraction from the sepharose CL-6B column. On the other hand, the flow-through fraction from polymixin B-agarose column did not show detectable priming activity. (D) Dose dependency of priming activity of <i>P. aeruginosa</i> LPS on GN8-induced ROS production. LPS concentration used for the experiments (A) to (C) was 0.1 µg/ml and GN8 concentration for the experiments (A) to (D) was 0.08 ng/ml. Rice cells were pretreated with the LPS for 120 min at 25°C and successively treated with GN8. Error bars indicate standard deviation.</p