蒜头果半寄生特性研究

Root Hemiparasitic Characteristics of Malania oleifera

蒜头果为我国特有的单种属濒危保护植物,因其种仁油脂中富含神经酸而具有很高的经济开发价值,但人工种植的成活率和保存率都很低.于2016年12月对云南省广南县天然分布区蒜头果的根系进行了调查,发现其根部具有特殊的瘤状结构,依形态特征观察判定该结构为吸器,蒜头果是一种根部半寄生植物.进一步通过对寄生结构的切片观察和配置寄主植物的共培养盆栽试验,证实了蒜头果的半寄生特性.盆栽试验发现蒜头果幼苗在无寄主植物伴生的条件下也能存活,但能与多种寄主植物形成寄生关系,对寄主种类选择的专一性不强.蒜头果自身的根系间会互相形成很多吸器,具有明显的自寄生现象.因寄主植物的不同,蒜头果在寄主植物根系上形成的吸器和自寄生吸器的数量、 平均直径、 最大直径、 自寄生吸器所占比例及苗木生物量存在显著差异,表明蒜头果对寄主植物有较明显的偏好性.蒜头果幼苗与吊兰表现出紧密的寄生关系,无论是吸器数量还是苗木生物量指标都显著优于其他各处理,在蒜头果人工种植中吊兰作为寄主植物具有一定的应用前景.本研究的结果有助于解决目前蒜头果人工种植成活率和保存率低的问题,促进这一珍稀濒危物种的保护、 繁育及利用.

Malania oleifera is an endangered monotypic species endemic to China,with promising economic value for the high content of nervonic acid in seed.However the planting of this species was seriously limited by the low survival rate in the field.In December 2016,the root system of Malania oleifera naturally growing at Guangnan county of Yunnan Province were investigated,warts were prevalently observed on the root,with the same morphological characteristics of haustorium,indicated that Malania oleifera was a hemiparasitic plant.Slice observation and pot culture experiment further verified the root hemiparasitism of Malania oleifera.In pot culture experiment,Malania oleifera could survive without host,in the treatments with host plant,Malania oleifera developed haustoria and contacted the roots of varied hosts.It was found that the haustoria contacted not only the host roots,but also the roots of its own.The number and diameter of haustorium,the number percentage of haustorium contacted its own root and its seedling biomass varied with tested host plants,showing the preference towards host plant to a certain extend.Among the tested host plants in this study,Malania oleifera developed a close parasitic relationship with Chlorophytum comosum,both haustorium index and seedling biomass were significantly higher than other treatments,indicating the prospect of Chlorophytum comosum as a host candidate in cultivation of Malania oleifera.The results of this study will contribute to solve the problem of low survival rate of Malania oleifera in field planting,and promote the conservation,propagation,cultivation and utilization of this valued tree species.