薇甘菊可溶性蛋白和抗氧化酶活性对田野菟丝子不同寄生密度的响应

Responses of Mikania micrantha to parasitization of Cuscuta campestris in total soluble protein content and activities of antioxidant enzymes

关键词:  生物防治  入侵杂草  寄生植物  抗氧化酶

Key words:  biological control  invasive weed  parasitic plant  antioxidant enzymes

摘要:

为探求利用寄生植物田野菟丝子对入侵杂草薇甘菊进行生物控制的有效措施，研究了薇甘菊对0、1、2、4和8棵田野菟丝子幼苗寄生在可溶性蛋白和一些抗氧化酶活性方面的响应。寄生后30 d，1棵田野菟丝子/株薇甘菊（以下简称棵/株）以上的寄生密度导致薇甘菊可溶性蛋白含量显著降低。和对照相比，在寄生密度为1棵/株时，超氧物歧化酶（SOD）和过氧化物酶（POD）活性显著增强；但随着寄生密度的加大而下降，而且在寄生密度为4棵/株时，SOD和POD分别等于和小于对照，在8棵/株时均显著小于对照。在各寄生密度下，寄主的过氧化氢酶（CAT）活性均小于对照，而SOD/CAT，SOD/POD和SOD/（CAT+POD）比率均大于对照。这些结果表明，田野菟丝子的寄生对薇甘菊可溶性蛋白和抗氧化酶活性的影响依赖于寄生密度，在野外利用田野菟丝子控制薇甘菊的最理想寄生密度是4棵/株，从而可为野外利用田野菟丝子控制薇甘菊的技术体系提供参考。

Abstract:

To develop efficient biocontrol techniques for the invasive weed Mikania micrantha，the use of the obligate parasitic plant，Cuscuta campestris Yuncker as a biological control was investigated. In this experiment，whether the impacts of the parasite on host soluble protein content and activities of some antioxidant enzymes were affected by the density of the parasite was tested. The responses of M.micrantha to parasitic densities of 0，1，2，4 and 8 individual seedlings of C.campestris per host plant were examined.On the 30th day of parasitization，infection with more than 1 C.campestris seedling significantly lowered soluble protein content. Compared with control，activities of superoxide dismutase (SOD) and peroxidase (POD) significantly increased at parasitic density of 1 parasite per host plant；but as parasitic density increased，both SOD and POD activities decreased.Moreover，SOD activity was not changed but POD activity was significantly decreased at parasitic density of 4 parasites per host，and both SOD and POD activities were significantly decreased at parasitic density of 8 parasites per host，compared with control. The infected plants had significantly lower catalase (CAT) activity but higher SOD/CAT，SOD/POD and SOD/ (CAT+POD) ratios than the control at all parasitic densities. The results indicated that the effects of C.campestris infection on M.micrantha were density dependent，which provided a basis for refining this strategy for biological control of M.micrantha. The optimal cost effective number of parasites to control M.micrantha was 4 per host plant in the field.