Xanthophyll Cycle and Non-Radiative Energy Dissipation in Sun and Shade Plants

There were large differences in photosynthetic rates between sun plants and shade plants under natural conditions. They had different capacities to adapt to high light stress. The light saturation rate of the former is higher than that of the later. Comparing with shade plants, sun plants generally possessed the bigger Violaxanthin (V) +Antheraxanthin (A) +Zeaxanthin (Z) pool size, while Zand Z+A contents all exceeded more than that of shade plants. Within sun plants or shade plants, the differences of Z, Z+A and V+A+Z contents in different species were relatively smaller under the same situation and the content of Ais basically consistent. Whether it was sun plant or shade plant, the contents of Z, Z+A and V+A+Z all apperently presented a positive correlation with NPQ. The more the xanthophyll content was, the higher the NPQwas.The contents of Zand Z+A were basically proportional to the V+A+Z pool size in both species. So it showed that the content of Z+A was still the major factor to affect NRDin different species. As the xanthophyll pool sizes could obviously affect the maximal contents of Z and A, so they were also regarded as important factors to limit the NRD in different species.