Effect Of Ustilago Esculenta Infection On Photosynthetic Gas Exchange And Chlorophyll Fluorescence In Zizania Latifolia

A smut fungus Ustilago esculenta plays a vital role in the enlargement of infected culm of Zizania latifolia. An experiment was conducted to analyze the effects of infection of this smut fungus on plant growth, total chlorophyll content, photosynthetic gas exchange and chlorophyll fluorescence to determine which processes determining photosynthesis are affected by this taxon. Our results showed that plants infected with U. esculenta displayed decreased plant growth in terms of plant height, leaf width and leaf length, but a significant increase in above-ground biomass production was observed as compared with U. esculenta-free plants.Results revealed total chlorophyll content was greatly increased in infected Z. latifolia compared with U. esculenta-free plants. And net photosynthetic rate (Pn), transpiration (Tr) and stomatal conductance (Gs) were often higher than U. esculenta-free plants, but intercellular CO2concentration (Ci) was slightly lower in infected plants compared with control plants. Infected Z. latifolia showed a higher light saturation point and had promoted net photosynthetic rate at higher light intensities (over1200umol m-2-1). Meanwhile, infected plants had higher net photosynthesis rate at higher CO2concentrations (over800μmol m-2s-1). Maximum carboxylation rate of Rubisco (Vc, max) and maximum rates of RuBP regeneration (Jmax) were also elevated by U. esculenta infection. For the chlorophyll fluorescence parameters, the infected plants often showed relatively higher values in the quantum efficiency of photosystem Ⅱ photochemistry (OPSⅡ), electron transport rate (ETR) and photochemical quenching (qP) than control plants, but no marked difference was observed in non-photochemical quenching (NPQ). The above results suggested that photosynthetic capacity in infected Z. latifolia are promoted by U. esculenta infection.