强光胁迫对茅苍术生长、生理生化及关键酶基因表达的影响

目的:探究不同梯度的强光胁迫对茅苍术生长、生理生化及关键酶基因表达的影响,为规范化栽培茅苍术提供科学依据。方法:以两年生茅苍术种苗为实验材料,杨树林下(透光率18.26%~36.04%)作为对照组(ck),采用不同密度的遮荫网于7月下旬模拟不同程度(51.10%,80.73%,100%)的强光进行胁迫。观察茅苍术生长状态,于第0,5,10,15,20天测定茅苍术叶片的生理生化指标丙二醛(MDA)含量、细胞膜透性、脯氨酸(Pro)含量、抗氧化酶活性及叶绿素含量。通过实时荧光定量聚合酶链式反应(Real-time PCR)技术测定强光胁迫后茅苍术叶片中3-羟基-3-甲基戊二酸单酰辅酶A还原酶(3-hydroxy-3-methylglutaryl coenzyme A,HMGR)和法呢基焦磷酸合酶基因(farnesyl pyrophosphate synthase,FPPS)的相对表达量。结果:经过强光胁迫后,茅苍术叶片颜色由深绿色变为浅绿、黄绿色,叶片灼伤越来越严重;MDA含量、电导率及Pro含量随光强的增加总体呈上升趋势;过氧化物酶(POD),超氧化物歧化酶(SOD)和过氧化氢酶(CAT)均呈先升高再降低的趋势;叶绿素含量随光强的增加呈下降趋势;茅苍术叶片中HMGR相对表达量随光强的增加呈下降趋势而FPPS表达量呈先升后降的趋势。结论:实验结果表明在一定的强光胁迫下,茅苍术可通过提高抗氧化酶活性及调节渗透压物质含量以缓解强光胁迫的抑制作用;过高的强光胁迫则会导致茅苍术代谢机制失调,严重抑制植株生长。

Effect of Strong Light Stress on Growth,Physiological and Biochemical and Gene Expression of Key Enzymes in Atractylodes lancea

Objective: To explore the effect of strong light stress on the growth,physiological and biochemical and key enzyme gene expression of the Atractylodes lancea,in order to provide the scientific basis for the standardized cultivation of the A. lancea. Method: The two-year-old A. lancea seedlings were taken as experimental materials. Poplar forest (light transmittance between 18.26%-36.04%) was taken as control group(ck). Different density shading networks were used to simulate different degrees of high light stress (51.10%,80.73%,100%) in late July. The growth state of A. lancea was observed. On the 0^th,5^th,10^th,15^th,20^th days,the physiological and biochemical indexes of malondialdehyde (MDA) content,cell membrane permeability,proline (Pro) content,antioxidant enzyme activity and chlorophyll content in the leaves of A. lancea were measured. The relative expression levels of 3-hydroxy-3-methylglutarate monoacyl coenzyme A reductase (3-hydroxy-3-methylglutaryl coenzyme A,HMGR) and farnesyl pyrophosphate synthase gene (farnesyl pyrophosphate synthase,FPPS) in leaves of A. lancea under intense light stress were determined by real-time fluorescence quantitative PCR(Real-time PCR). Result: After strong light stress,the color of the leaves of A. lancea changed from dark green to light green and yellowish green,and the burn of leaves became more and more serious. The contents of MDA,conductivity and Pro showed an upward trend with the increase of transmittance. Peroxidase (POD),superoxide dismutase (SOD) and catalase (CAT) tended to increase first and then decrease. The chlorophyll content decreased with the increase of light transmittance. The relative expression of HMGR in leaves of A. lancea decreased with the increase of light transmittance,while FPPS increased first and then decreased. Conclusion: The results showed that A. lanceaa could alleviate the inhibition of strong light stress by increasing the activity of antioxidant enzymes and regulating the content of osmotic pressure under certain strong light stress. Excessively strong intensity light stress leads to disequilibrium of metabolic mechanism of A. lancea,and seriously inhibits the plant growth.