低温胁迫下鹿蹄草生理响应变化分析

[目的]探寻低温胁迫对鹿蹄草的影响机制。[方法]以鹿蹄草叶片为材料,测定不同冷处理条件下叶片各种保护酶(SOD、POD、CAT)、丙二醛、叶片相对电导率、脯氨酸、可溶性蛋白和可溶性糖等含量变化情况。[结果]叶片的SOD酶与POD酶均呈现先升后降的趋势,但变化幅度不尽相同;CAT酶则呈现先降后升的趋势,但变化幅度不大。丙二醛的积累与叶片相对电导率均呈现上升趋势。脯氨酸、可溶性蛋白质和可溶性糖含量随胁迫时间增加呈现出明显的相关性。[结论]该方法研究了低温胁迫对鹿蹄草的影响,为鹿蹄草的合理利用提供了依据。

Degeneration of photosynthetic capacity in mixotrophic plants, Chimaphila japonica and Pyrola decorata (Ericaceae)

The evolution of photosynthesis is an important feature of mixotrophic plants.Previous inferences proposed that mixotrophic taxa tend to retain most genes relating to photosynthetic functions but vary in plastid gene content.However,no sequence data are available to test this hypothesis in Ericaceae.To investigate changes in plastid genomes that may result from a transition from autotrophy to mixotrophy,the plastomes of two mixotrophic plants,Pyrola decorata and Chimaphila japonica,were sequenced at Illumina's Genome Analyzer and compared to the published plastome of the autotrophic plant Rhododendron simsii,which also belongs to Ericaceae.The greatest discrepancy between mixotrophic and autotrophic plants was that ndh genes for both P.decorata and C.japonica plastomes have nearly all become pseudogenes.P.decorata and C.japonica also retained all genes directly involved in photosynthesis under strong selection.The calculated rate of nonsynonymous nucleotide substitutions and synonymous substitutions of protein-coding genes(dN/dS) showed that substitution rates in shade plants were apparently higher than those in sunlight plants.The two mixotrophic plastomes were generally very similar to that of non-parasitic plants,although ndh genes were largely pseudogenized.Photosynthesis genes under strong selection were retained in the two mixotrophs,however,with greatly increased substitution rates.Further research is needed to gain a clearer understanding of the evolution of autotrophy and mixotrophy in Ericaceae.

Effect of Endophytic Fungus on Pyrola calliantha H. Andr Responsed to Cold Stress

This study measured the antioxidant enzyme activities of Pyrola under cold and endophytic fungal infection conditions[i.e.,peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)],and the contents of malondialdehyde(MDA),soluble sugar and soluble protein.In addition,the changes in the anatomical structure of Pyrola vegetable organ during cold stress upon inoculation with a synergistic endophytic fungus were also analyzed.It was found that the soluble sugar and soluble protein contents and POD,SOD and CAT activies of Pyrola all increased,when the plants were exposed to temperature of-5℃.In particular,the MDA contents and the POD activies significantly increased compared with those of the control.In addition,the soluble sugar and soluble protein contents increased during the treatment,which involved in both inoculation with an endophytic fungus and low temperature;however,with a reduction in the concentration of endophytic fungus,those two indicators decreased.The optimal concentration of endophytic fungus was 5×10^(7) cfu·mL^(-1).From the anatomical structure of Pyrola root,endophytic fungi were found to improve the health of.Pyrola in cold weather.These results showed that endophytic fungi played a vital role in the growth of Pyrola,which was an evergreen plant that could survive exposure to low temperature.