模拟干旱胁迫对诸葛菜无机碳利用的影响

为研究喀斯特适生植物的碳酸酐酶应对岩溶干旱机制,本实验以诸葛菜为研究对象,以聚乙二醇(polyethyleneglycol,PEG)浓度为控制因子,已知δ13 C值的NaHCO3为无机碳源模拟喀斯特干旱逆境,测定分析不同浓度PEG下诸葛菜叶片的碳酸酐酶活力、稳定碳同位素组成、净光合速率和叶绿素荧光等指标。结果表明,诸葛菜的碳酸酐酶活力在PEG胁迫浓度低于40g·L-1时显著性增高;碳酸氢根离子利用份额随PEG浓度变化不同,10g·L-1时利用份额最多,20g·L-1时诸葛菜的碳酸氢根离子利用份额与对照相比无显著性差异;净光合速率随着PEG浓度的增加而下降,且下降趋势成非线性关系;PEG浓度低于40g·L-1时,荧光参数显示光合系统未受到损坏。适当的渗透逆境胁迫下,诸葛菜表现出高碳酸酐酶活力应对逆境。诸葛菜可凭借碳酸酐酶作用交替利用碳酸氢根离子和大气中的二氧化碳,补充诸葛菜因渗透胁迫造成的水分和二氧化碳的不足,保护光合系统,减缓净光合速率的下降。

The Effect of Simulating Drought Stress on Inorganic Carbon Used by Orychophragmus Violaceus

This paper dealt with the contribution of carbonic anhydrase in karst-adaptable plants on the mechanism of resistance against karst drought. Orychophragmus violaceus was cultivated under nutrient solutions with different concentrations of polyethyleneglycol (PEG) and sodium bicarbonate of known stable carbon isotopic composition. Carbonic anhydrase activity, stable isotopic composition, net photosynthesis, and chlorophyll fluorescence characteristics in leaves of Orychophragmus violaceus were studied and compared. The results showed that carbonic anhydrase activity increased significantly with increasing PEG when the concentration was less than 40 g·L^-1. The HCO₃^- use proportion varied with PEG concentrations. The highest HCO₃^- use proportion was the treatment under 10 g·L^-1 PEG level. Compared to the control, there was no significant difference in the HCO₃^- use proportion under 20 g·L^-1 PEG level. With the increase of PEG concentrations, net photosynthetic rate reduced in a nonlinear relationship. Fluorescent parameters showed that the photosynthetic system was not damaged when PEG concentrations were less than 40 g·L^-1. Under a certain strength of osmotic stress, Orychophragmus violaceus showed high carbonic anhydrase activity to resist adversity. By means of carbonic anhydrase, Orychophragmus violaceus can alternatively use bicarbonate as inorganic carbon sources, supplement the deficiency of moisture and carbon dioxide, protect photosynthetic system, and slow down the decline of net photosynthetic rate.