In C4 plants, carbonic anhydrase (CA) facilitates both the chemical and isotopic equilibration of atmospheric CO2 and bicarbonate (HCO3-) in the mesophyll cytoplasm. The CA-catalyzed reaction is essential for C4 photosynthesis, and the model of carbon isotope discrimination (Delta13C) in C4 plants predicts that changes in CA activity will influence Delta13C. However, experimentally, the influen...

Greenhouse-grown plants of Xanthium strumarium L. were exposed in a growth cabinet to 10 C during days and 5 C during nights for periods of up to 120 hours. Subsequently, CO(2) exchange, transpiration, and leaf temperature were measured on attached leaves and in leaf sections at 25 or 30 C, 19 C dew point of the air, 61 milliwatts per square centimeter irradiance, and CO(2) concentrations betwe...

many phragmites-dominated wetlands have been markedly salinized and alkalinized in the songnen plain, northeastern china. agricultural wastewater with high nitrogen content has been discharged into these alkalinized-salinized wetlands. to understand the effect of salinity-alkalinity on reed (phragmites australis) seedlings at various nitrogen levels, we examined photosynthesis rate, chlorophyll...

The effects of gas phase O(2) concentration (1%, 20.5%, and 42.0%, v/v) on the quantum yield of net CO(2) fixation and fluorescence yield of chlorophyll a are examined in leaf tissue from Nicotiana tabacum at normal levels of CO(2) and 25 to 30 degrees C. Detectable decreases in nonphotochemical quenching of absorbed excitation occurred at the higher O(2) levels relative to 1% O(2) when irradia...

Photosynthesis of green plants, algae and cyanobacteria is powered by sunlight. It uses water as ultimate donor of electrons for the reduction of CO2 to yield carbohydrates. Photosystem II (PS II), a water^ plastoquinone oxidoreductase, is the key enzyme of oxygenic photosynthesis. It is an integral protein of the thylakoid membrane. PS II is functionally bipartite, its photosynthetic reaction ...

The effects of ethylene evolved from ethephon on leaf and whole plant photosynthesis in Xanthium strumarium L. were examined. Ethylene-induced epinasty reduced light interception by the leaves of ethephon treated plants by up to 60%. Gas exchange values of individual, attached leaves under identical assay conditions were not inhibited even after 36 hours of ethylene exposure, although treated l...

It has been shown recently that in spinach leaves (Spinacia oleracea) net photosynthesis and nitrate reduction are closely linked: when net photosynthesis was low because of stomatal closure, rates of nitrate reduction decreased (WM Kaiser, J Förster [1989] Plant Physiol 91: 970-974). Here we present evidence that photosynthesis regulates nitrate reduction by modulating nitrate reductase activi...