Effect of bicarbonate treatment on photosynthetic assimilation of inorganic carbon in two plant species of Moraceae

Abstract

Excessive levels of bicarbonate adversely affect the growth and metabolism of plants. Broussonetia papyrifera (L.) Vent. and Morus alba L., belonging to family Moraceae, possess the favorable characteristics of rapid growth and adaptability to adverse environments. We examined the response of these two plant species to bicarbonate stress in terms of photosynthetic assimilation of inorganic carbon. They were exposed to 10 mM sodium bicarbonate in the culture solution for 20 days. The photosynthetic response was determined by measuring the net photosynthetic rate of the leaf, water-use efficiency, and chlorophyll fluorescence on days 10 and 20. The bicarbonate-use capacity of the plants was studied by measuring the carbonic anhydrase activity and the compositions of the stable carbon and hydrogen isotopes. The photosynthetic response to high concentration of bicarbonate varied with plant species and treatment durations. High concentrations of bicarbonate decreased the photosynthetic assimilation of inorganic carbon in the two plant species to half that in the control plants on day 10. Bicarbonate treatment did not cause any damage to the reaction centers of photosystem II in Morus alba; it, however, caused a decline in the quantum efficiency of photosystem II in B. papyrifera on day 20. Moreover, B. papyrifera had a greater bicarbonate-use capacity than M. alba because carbonic anhydrase converted bicarbonate to CO 2 and H 2 O to a greater extent in B. papyrifera. This study showed that the effect of bicarbonate on photosynthetic carbon metabolism in plants was dual. Therefore, the concentration of bicarbonate in the soil should first be considered during afforestation and ecological restoration in karst areas.

Beneficial Effects of Potassium on Growth, Water Relations, Mineral Accumulation and Oxidative Damage of Beta vulgaris in Sodic-alkaline Condition

“…Therefore, K + plays a crucial role in NaHCO 3 -and Na 2 CO 3 -treated Swiss chard. At the same time, excessive CO 3 2-has its own toxic effect on plant growth because of adverse effects on protein synthesis, respiration, and the absorption of nutrients (Wu and Xing, 2012). High contents of HCO 3 -strongly affect the availability of several micronutrients, especially Fe, and it is often considered to be the primary factor inducing Fe chlorosis in leaves (Colla et al, 2010).…”

Biomass Production of Three Biofuel Energy Plants’ Use of a New Carbon Resource by Carbonic Anhydrase in Simulated Karst Soils: Mechanism and Capacity

“…CA activity (WAU g −1 (FW)) of the leaf tissue was determined every seven days during the stress phase using the method reported previously [11]. The fourth youngest fully expanded leaf from the top of the plant was used.…”

“…Although these factors adversely affect the survival and growth of plants, the growth of some plants was improved by the regulation of carbonic anhydrase (CA, EC 4.2.1.1) gene expression, including pH regulation, ion exchange, respiration, CO 2 transfer, and photosynthetic CO 2 fixation. These plants are classified as karst-adapted and can grow across the karst regions in limestone soils [9,11].…”

“…The resulting CO 2 and H 2 O are used in photosynthesis. Additionally, in the guard cells of plant leaves, CA effectively regulates gas exchange between plants and the atmosphere [11,[13][14][15]. Both lower plants and higher plants, CA has been attracting attention in the biomass field.…”

“…To distinguish between atmospheric CO 2 and exogenous bicarbonate sources of carbon, a stable carbon isotope technique was successfully used to trace the metabolism of inorganic carbon sources during photosynthesis [22]. Using a method based on stable carbon isotopes, we quantified the proportion of bicarbonate use by plants [11]. Although the conversion to biomass from bicarbonate by the activity of CA has been proposed in studies of plant biomass production for energy [17,18,20], the mechanism and the capacity for bicarbonate use in plants in karst habitats are not fully understood.…”