| Huperzia serrata is perenninal herbage of Huperziaceae family.It's an efficacious traditional Chinese medicine.It contains Huperzine A,which has a good curative effect on Alzheimers disease.With the environmental deterioration and Green House effect increase,high temperature stress has become one of the major environmental stresses that adversely affect plant growth.Study on the effects of physiological characteristic of Huperzia serrata under high temperature stress can provide theoretical basis for artificial planting of Huperzia serrata.This paper regards Huperzia serrata as experimental materials,the temperature treatments included:constant temperature at25℃, alternating temperatures at30℃,35℃,40℃, we observed the effects of the growth situation of Huperzia serrata under high temperature stress and study the biological characteristic of Huperzia serrata through observing the paraffin section which made by it's roots, stems and leaves. Meanwhile, investigated the changes of it's chloroplast ultrastructure under high temperature stress by TEM. We measured some characters of physiology such as soluble sugar content, soluble protein content, free proline content, SOD activity, POD activity, MDA content, chlorophyll (Chl) content,changes of electrical conductivity, at the same time,analyzed of these indexes, the main results as follows:1. Huperzia serrata is an old-age group of Huperziaceae family, its root only has primary structure and ectomycorrhiza, The stele of the root is protostele, thin leaves and loose arrangement of mesophyll cell, the shape and number of stomatal is as same as higher plants.2. The effects of physiological characteristic and growth situation of Huperzia serrata under30℃high temperature stress was not significant. After eight days, some of leaves appeared moderate dehydration. Begin with35℃high temperature stress,the growth situation of Huperzia serrata had been changed. Some leaves drooped and turned yellow, appeared obviously dehydration. Under40℃high temperature stress, some leaves appeared severe dehydration along with extending process time, all of the top leaves turned yellow. After eight days,the plant lost activities. 3. The changes of solute content of Huperzia serrata under high temperature stress was significant. The soluble sugar content increased at firest which was followed by a decline. There was a positive correlation between soluble sugar content and stress time under35℃and40℃high temperature stress, the correlation coefficients were0.977(*P<0.05)and0.955(*P<0.05). The free proline content showed a positive correlation with extending process time while the soluble protein content showed a negative correlation with extending process time. Under35℃and40℃high temperature stress, there was a negative correlation between soluble protein content and stress time, the correlation coefficients were-0.995and-0.987(**P<0.01). On the sixth day under40℃, The free proline content was6.4times higher than CK. There was a positive correlation between free proline content and stress time under35℃and40℃high temperature stress, the correlation coefficients were0.986(*P<0.05) and0.937(*P<0.05). The effects of soluble protein content of Huperzia serrata under high temperature stress was the most significant among the other soluble matter. There were significant difference between stress time and the changes of soluble matter content.4. High temperature stress damaged the membranous structure of Huperzia serrata cells. With the increasing of temperature and the prolonging time of high temperature stress,the electrical conductivity of leaf cells kept elevating and appeared greatest value on the eight day under40℃high temperature stress which was1.77times higher than relative CK. There was a positive correlation between the electrical conductivity and stress time under35℃and40℃high temperature stress, the correlation coefficients were0.965(*P<0.05) and0.994(*P<0.05). With the increasing of temperature, the MDA content kept elevating and the content was1.32times higher on the eight day under40℃high temperature stress. The correlation between the MDA content and stress time was positive, the correlation coefficients were0.985(*P<0.05) and0.987(*P<0.05). There were significant difference between stress time and the changes of MDA content and electrical conductivity.5. High temperature stress influenced the activity of the protecting enzymes of antioxidant system. The SOD activity increased at firest which was followed by a decline, on the fourth day of40℃, it appeared greatest value, on the sixth day, the activity declined and appeared the lowest value on the eighth day. The POD activity showed a negative kept stable under25℃and30℃, On the first two days of35℃, the POD activity increased and the declined, at last the activity kept stable but still lower than CK. The POD activity declined along with the prolonging time of40℃high temperature stress and decreased to the lowest value on the eight day under40℃high temperature stress. The correlation between the POD activity and stress time was negative, the correlation coefficients were-0.9948(**P<0.05). The result showed that the activities of protecting enzymes of antioxidant system had been damaged by the high temperature stress.6. The high temperature stress destroyed chlorophyll (Chl). The chlorophyll (Chl) content declined along with the increasing of temperature and the prolonging time of high temperature stress, especially under35℃and40℃. The chlorophyll (Chi) content declined to the lowest value on the sixth day of40℃. The high temperature stress effect influenced more on chlorophyll-a content than chlorophyll-b content. The results indicate the value chlorophyll a/b was between1.62-2.2, with the increasing of temperature and the prolonging time of high temperature stress, the ratio was on the decline and the raised slowly.7. High temperature stress damaged the chloroplast ultrastructure of Huperzia serrata. The chloroplast ultrastructure integrity under room temperature, it has bigger starch grain and fewer osmiophilic globules. The shape of chloroplast changed more and the structure of chloroplast membrane was fuzzy under35℃, the starch grain bigger than before and the number of osmiophilic globules increased more. the boundary of chloroplast envelope was indistinct Under40℃high temperature stress, the boundary of chloroplast envelope was indistinct and appeared fracture, the thylakoid arrangement became disordered, grana lamellae and stroma lamellae appeared to be obscured or even disintegrated. The result showed that the ultrastructure of chloroplasts was damaged by heat stress. |
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