弱光胁迫对圆叶决明根系生长的影响及其生理响应机制

Effect of Low Light Stress on the Root Growth of Chamaecrista rotundifolia and Its Physiological Response Mechanism

为了研究弱光胁迫对圆叶决明根系生长的影响,通过测定不同光照强度下[自然光强(CK)、50%光强(LI 50%)、30%光强(LI 30%)、10%光强(LI 10%)]根系生理代谢相关指标,阐释弱光胁迫的影响机制。结果表明:弱光胁迫下,圆叶决明生物量、根冠比、根系活力显著降低,LI 30%、LI 10%水平下的根系Na^(+)-K^(+)-ATP酶活性显著降低。随着弱光胁迫加深,根系SOD、CAT活性呈下降趋势,各处理间的SOD活性差异显著;根系O_(2)^(-)产生速率、H_(2)O_(2)含量、MDA含量及膜透性呈现上升的趋势。与CK相比,处理LI 50%、LI 30%、LI 10%根系可溶性糖含量、淀粉含量显著降低;根系硝酸还原酶活性呈下降趋势(各处理间差异显著),同时根系蛋白酶与核糖核酸酶活性呈上升趋势(LI 30%、LI 10%差异极显著),并影响根系核酸含量极显著降低。综上所述,弱光胁迫降低了圆叶决明根系活力,破坏了根系膜系统,降低了根系碳水化合物的分配,影响了根系蛋白合成,加速了根系衰老,最终影响根系的生长。

In order to study the effect of low light stress on the root growth of Chamaecrista rotundifolia,the relevant indexes of root physiological metabolism under different light intensities,including the natural light intensity(CK),50%light intensity(LI 50%),30%light intensity(LI 30%),10%light intensity(LI 10%),were measured to explain the mechanism of low light stress.The results showed that the biomass,root-shoot ratio and root activity of Chamaecrista rotundifolia were significantly decreased under the low light stress,and the enzyme activity of Na^(+)K^(+)-ATP in roots under the levels of LI 30%and LI 10%was significantly decreased.With the deepening of low light stress,the activities of SOD and CAT in roots had a downward trend,and the difference of SOD activity among different treatments was significant.The O_(2)^(-)production rate,H_(2)O_(2) content,MDA content and membrane permeability of root system showed a increasing trend.Compared with the CK,the contents of soluble sugar and starch in roots under the treatments of LI 50%,LI 30%,and LI 10%were significantly decreased.The activity of nitrate reductase in roots showed a decreasing trend(significant difference among various treatments),while the activities of protease and ribonuclease in roots showed an increasing trend(extremely significant difference between the treatments of LI 30%and LI 10%).As a result,the nucleic acid content in roots was significantly reduced.In summary,the low light stress could reduce the root activity of Chamaecrista rotundifolia,destroy the root membrane system,reduce the distribution of root carbohydrates,affect the root protein synthesis,accelerate the root senescence,and ultimately affected the root growth.