从木榄叶片超微结构所受的影响评估外来种拉关木的化感作用

Allelopathic effects of exotic mangrove species Laguncularia racemosa on leaf ultrastructure of Bruguiera gymnorhiza seedlings

探讨外来速生红树植物拉关木(Laguncularia racemosa)扩张过程中潜在的化感作用,为其入侵风险评估提供参考。通过室内栽培试验测定拉关木根、枝、叶、果的水浸液不同质量浓度(0.1 g·mL^(-1)、0.5 g·mL^(-1))对我国乡土红树植物木榄(Bruguiera gymnorhiza)幼苗叶片超微结构的影响。结果表明,在拉关木根、叶、果的水浸液低浓度(0.1 g·mL^(-1))处理下,木榄幼苗的叶肉细胞内的叶绿体紧密排列在细胞壁周围,线粒体结构保持完好;而在拉关木枝的水浸液低浓度(0.1 g·mL^(-1))处理下,木榄幼苗叶肉细胞内的液泡轻微皱缩,出现轻微的质壁分离现象。拉关木枝、果水浸液高浓度(0.5 g·mL^(-1))处理下,木榄幼苗叶片叶肉细胞的叶绿体内的淀粉粒变多,变大,线粒体内部结构出现降解;拉关木根的水浸液高浓度(0.5 g·mL^(-1))处理下,部分叶绿体结构受到破坏,但线粒体结构基本保持较好;而在拉关木叶的水浸液高浓度(0.5 g·mL^(-1))处理下,木榄叶片叶肉细胞的超微结构基本保持完好,表明拉关木叶水浸液对木榄幼苗的化感抑制作用弱。本研究中拉关木各器官高浓度(0.5 g·mL^(-1))水浸液对木榄幼苗叶片超微结构的化感作用强弱顺序为:枝>果>根>叶。

In order to provide a reference for the invasion risk assessment of fast-growing alien mangrove species of Laguncularia racemosa,the aqueous extracts of different concentrations(0.1mg·L-1,0.5mg·L-1)of roots,stems,leaves and fruits of L.racemosa were used to determine the allelopathic effects on the leaf ultrastructure of seedlings of Bruguiera gymnorhiza native species in China by indoor cultivation experiment.The results of this study show that when subjected to the concentration of0.1mg·L-1aqueous extracts from L.racemosa roots and fruits,the number of chloroplasts in the mesophyll cells of B.gymnorhiza seedlings increased and mitochondria were delimited by a double mitochondria membrane,as well as showed clear cristae inside an electrondense stroma;when subjected to the concentration of0.1mg·L-1aqueous extracts of L.racemosa stems,the vacuoles of the mesophyll cells in the mesophyll cells of B.gymnorhiza were slightly shrunk and a slight wall separation was observed.Whereas subjected to the concentration of0.5mg·L-1aqueous extracts from L.racemosa stems and fruits,the size and number of starch grains of chloroplast were increased,and the mitochondriawere deformed and seriously degraded.When subjected to the concentration of0.5mg·L-1aqueous extracts from L.racemosa roots,some parts of chloroplast were damaged,but the mitochondria structure basically remained intact;whereas subjected to the concentration of0.5mg·L-1aqueous extracts from L.racemosa leaves,both the chloroplast and mitochondria in mesophyll cells of B.gymnorhiza seedlings basically remained intact,which showed that the inhibitory effect of the aqueous extract of L.racemosa leaves was weak.When subjected to the concentration of0.5mg·L-1aqueous extracts from different organs of L.racemosa,the allelopathy intensity order on the ultrastructure of leaves of B.gymnorrhiza seedlings was:stem>fruit>root>leaves.