虎杖叶片两种次生代谢物含量的纬度变异及影响因子

Latitudinal Variation and Influencing Factors of Two Secondary Metabolites in Reynoutria japonica Leaves

叶片次生代谢物质含量是植物响应外界环境变异的重要性状,与植物适应策略与生态系统过程紧密相关。以往研究认为,物种内次生代谢物质含量的纬度变异受到叶片草食作用、气候和土壤因子的综合影响,但不同因素的相对贡献尚未得到一致性结论。为此,本研究对广泛分布于我国的药用植物虎杖(Reynoutria japonica Houtt.)进行了野外调查,探讨了虎杖叶片中两种酚类次生代谢物质含量的纬度变异格局,并结合草食作用与非生物环境因子分析了影响其含量变异的关键因素及相对重要性。结果表明,虎杖叶片中白藜芦醇含量随纬度增加而显著降低,总单宁含量随纬度变化未呈现显著变异。多元回归结果显示,两种次生代谢物的含量均与生境温度的季节性呈显著正相关,叶片白藜芦醇含量还与年降水量、太阳辐射年较差和叶片草食作用显著负相关。由此可见,虎杖叶片中两种酚类次生代谢物质的含量是以温度季节性为主的多种环境因子综合影响的结果,暗示不同次生代谢物质可能具有多种不同的生态功能。本研究结果加深了对植物叶片次生代谢物质的纬度变异格局及其成因的认识,同时对虎杖资源的开发利用也具有一定参考价值。

Plant secondary metabolites are an essential functional trait in response to the varying environments,which are of great importance for plant adaptative strategies and ecosystem processes.Previous studies have shown that the concentration of secondary metabolites is associated with variations of herbivore pressure,climate and soil nutrient availability.However,the relative contributions of different factors to the concentration of secondary metabolites remain unclear.In this study,we conducted a field survey for a widely distributed plant species,Japanese knotweed(Reynoutria japonica Houtt.),along a latitudinal transect across central and southeast China.We measured the concentration of two phenolic compounds(resveratrol and total tannins)in leaves from different R.japonica populations,and tested whether the variation of herbivore pressure,climate and soil nutrient contributed to the content variation of both phenolic compounds.We found that resveratrol concentration decreased with increasing latitude,but no significant latitudinal variation was detected in total tannin content.The contents of both metabolites were positively correlated with temperature seasonality,and the resveratrol content was also negatively correlated with the gradients of annual precipitation,solar radiation annual range and herbivore pressure.The concentrations of both phenolic compounds in R.japonica leaves were influenced mainly by temperature seasonality,and less influenced by the other environmental factors.Our results indicate that different secondary metabolites may have different ecological functions.Future studies need to consider multiple influencing factors on the concentration of secondary metabolites,and should pay more attention to the internal relationship between secondary metabolites and other leaf functional traits.