Chilling Tolerance Modulates Low Temperature Induced Photosynthesis Changes in Zizania latifolia Turcz

Resumo

Zizania latifolia Turcz is a delicious aquatic vegetable cultivated in southern and eastern Asian. This study aimed at providing the mechanisms underlying chilling tolerance inZizania latifolia Turcz using two well-known cultivars: "Longjiao 2" and "911", which are chilling tolerant and sensitive, respectively. Plants were harvested at different time points and analyzed by physiological methods. We found that severe cold stress induced photosynthesis inhibition (5 ℃) resulted from non-stomatal factors. However, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of the cultivar "Longjiao 2" were higher than that of "911" with more gradual variations. Six parameters of chlorophyll fluorescence including latent activity of PSII (Fv/F0), efficiency of primary photochemistry (Fv/Fm), photochemical quenching (qP), non-photochemical quenching (qN), quantum yield of electric transport (Yield) and the ratio of electric transport at PSII (ERT) were analyzed in the two Zizania latifolia T. varieties. We found that "Longjiao 2" had higher Fv/Fm and qN than “911” while qP values were only slightly different for the two lines. In our experiments, Yield and ERT changed in the same fashion in both "Longjiao 2" and "911. In addition, the ability of heat dissipation of "Longjiao 2" was higher than that found in "911". These data suggest that Zizania latifoliaTurcz induces chilling tolerance by modulating critical pathways including photosynthesis and energy dissipation.