Plant growth and photosynthetic performance of Zizania latifolia are altered by endophytic Ustilago esculenta infection

An experiment was conducted to determine how photosynthesis was affected in Zizania latifolia Turcz. plants by infection of the endophytic smut fungus Ustilago esculenta. The results showed that U. esculenta infection induced a decreased plant height, but significantly increased above-ground biomass production as compared to control plants. Infected plants also exhibited higher Pn and chlorophyll content. In U. esculenta mycelia-sporidial infected plants, Pn, Gs and E generally were higher than those in sporidial infected plants. Compared to control plants, infected plants showed a higher light saturation point (LSP), apparent quantum yield (AQY) but a lower light compensation point (LCP). All leaves at different positions in infected plants showed higher Pn than control plants. The highest Pn was observed in the 4th leaf of infected plants, while it was the 3rd leaf in control plants. Infected plants generally showed relatively higher chlorophyll a fluorescence parameters in ΦPSII, ETR and qP than control plants. Maximum carboxylation rate of Rubisco (Vc, max) and maximum rate of RuBP regeneration (Jmax) were also elevated during U. esculenta infection. Our results revealed that promotion of photosynthetic efficiency was therefore probably mainly due to effects on non-stomatal processes by U. esculenta infection.