Systemic Signaling in the Photosynthetic Induction Phase of Calamagrostis angustifolia on the Sanjiang Plain Wetland of Northeast China

Deyeuxia angustifolia was grown in the Sanjiang plain wetland The treatments with different light intensities on the different leaf area at different positions, effects of illumination on the photosynthetic induction process of the leaves without preillumination (target leaves) was studied systematically. The possible mechanism and the signal transduction pathway of the systemic regulation were explored. The results showed that illumination of systemic leaves significantly increased the photosynthetic induction rate of target leaves. The time for reaching 50% of the maximum photosynthetic rate in the target leaves was reduced by about 19%, and the time for reaching 90% by about 27%. Either one or multiple systemic leaves were pre-illuminated and the photosynthetic induction rates of target leaves were all significantly accelerated. No significant difference was detected on the extent of the promotion effects of photosynthetic induction rates in target leaves. When the systemic leaves were illuminated with a Photosynthetic Photon Flux Density (PPFD) of 30 mu mol m(-2) s(-1), the photosynthetic induction rate of target leaves was not significantly enhanced. When the systemic leaves were illuminated with PPFDs of 100, 600 or 1300 mu mol m(-2) s(-1), photosynthetic induction rates of target leaves were significantly increased for all values; however, no significant differences were found on the extents of the enhancement effects on the photosynthetic induction rates of the target leaves when the systemic leaves were treated with more than these three light intensities. An effective systemic signaling could only be produced when the systemic leaves were illuminated with a light intensity above a certain threshold, and as soon the illumination exceeded this threshold, the strength of the systemic signaling did not increase with further increase in the light intensity. (C) 2020 Friends Science Publishers