克隆整合和模拟沉积物淹埋对外来水生植物粉绿狐尾藻(Myriophyllum aquaticum)生长和抗氧化系统的影响

Effects of clonal integration and simulated sediment burial on the growth and antioxidant system of the introduced aquatic plant Myriophyllum aquaticum

多数外来入侵水生植物都是克隆植物,而目前关于克隆整合属性对其入侵性潜在影响的研究仍旧缺乏.本文通过研究克隆整合(匍匐茎连接)和模拟沉积物淹埋(3 cm厚基质淹埋)对外来水生植物粉绿狐尾藻(Myriophyllum aquaticum)的生长、生物量分配和抗氧化酶活性的影响,探讨了克隆整合特性对粉绿狐尾藻耐受基质淹埋的作用机制.研究发现:基质淹埋显著降低了粉绿狐尾藻的生物量、总匍匐茎长度和分枝数,而克隆整合则显著促进了受淹埋分株的这些生长指标;基质淹埋显著降低了粉绿狐尾藻分株抗氧化酶(超氧化物歧化酶、过氧化物酶和过氧化氢酶)的活性,而克隆整合显著提升了受淹埋分株的抗氧化酶活性;此外,克隆整合显著降低了受淹埋分株的冠根比.以上结果表明:克隆整合效应能显著提升粉绿狐尾藻在基质淹埋胁迫下的活性氧清除能力,从而有助于其生长;能改变受胁迫分株生物量分配,提升其资源获取能力.因此,异质性环境胁迫下,粉绿狐尾藻的入侵性可能与其克隆整合属性密切相关.

Many exotic invasive aquatic plants are clonal plants, but the investigations on the influence of clonal integration on the potential invasive effects of these plants are still limited. This study investigated clonal integration （ stolon connection） and simula- ted sedimentation burial （3 cm sediment burial） on the growth, antioxidase activity and biomass allocation of the invasive aquatic macrophyte, Myriophyllum aquaticum, to explore the clonal integration effect on the tolerance mechanism of this species. We found that： sediment burial significantly reduced the final biomass, total stolon length and branch number, whereas these growth meas- ures of the ramets buried by sediment were markedly improved by stolon connection. The antioxidase activities （ superoxide dis- mutase, peroxidase and catalase） of the buried ramets were significantly lower than that in the control group, whereas those values were remarkably enhanced by clonal integration. Moreover, clonal integration significantly reduced the shoot/root ratio of those sed- iment buried ramets. The obtained results suggest that, under the stress of the sediment burial, clonal integration can enhance the re- active oxygen species scavenging ability of M. aquaticum ramets, thus improving their growth. Moreover, clonal integration can change the biomass allocation of the ramets, allowing them to acquire more abundant resources. Therefore, we conclude that the invasiveness of the M. aquaticum may be closely related to its clonal integration characteristic under heterogeneous environmental stresses.