【作者】 李洁；

【导师】 马丹炜；

【作者基本信息】 四川师范大学 ， 细胞生物学， 2007， 硕士

【摘要】 空心莲子草(Alternanthera philoxeroides Griseb)是苋科(Amaranthaceae)莲子草属(Alternanthera)多年生宿根草本植物,是广泛分布于我国的一种恶性入侵植物,对我国的农业经济、环境及生物多样性都造成了严重危害。研究空心莲子草的化感作用和遗传毒性机理对于有效治理该入侵种具有十分重要的意义。本研究采用生物测定法研究了空心莲子草水浸提液对莴苣、小麦和油菜等受体植物的种子萌发、幼苗生长以及某些生理过程的化感效应,结果表明空心莲子草水浸提液对3种受体植物种子萌发、幼苗生长以及部分生理过程均有不同程度的化感作用。空心莲子草水浸提液对莴苣、油菜种子的最终发芽率和发芽速率均有极显著的抑制作用,对种子萌发过程的影响主要表现在延迟了发芽;空心莲子草水浸提液显著抑制莴苣幼苗地上部分的生长,但对其地下部分的生长影响不大;在低浓度水浸提液促进小麦幼苗植株的生长,高浓度地下部分水浸提液则抑制了小麦幼苗的生长;在油菜幼苗的生长过程中,空心莲子草水浸提液对油菜根和苗的生长整体表现为抑制作用;空心莲子草水浸提液使受体植物体内丙二醛含量增加,超氧化物歧酶(SOD)活性和过氧化物酶(POD)活性呈现出显著变化,表明空心莲子草水溶性化感物质使受体植物受到了氧化胁迫,在一定程度上破坏了细胞膜的透性和功能;空心莲子草水溶性化感物质使植物体内的叶绿素b和类胡萝卜素含量发生变化,进而影响了植物的光合作用;空心莲子草的化感效应随不同器官和不同浓度而异,其地下器官的化感效应大于地上器官,化感效应与浓度呈正相关;受体植物幼苗生长对空心莲子草化感作用的敏感程度,随植物种类而异,3种受体植物中,油菜敏感性最强,莴苣、小麦次之,空心莲子草地下部分的化感作用强于地上部分,并且都和浓度正相关。首次采用蚕豆根尖微核技术研究了空心莲子草水溶性化感物质对植物有丝分裂的影响。结果表明空心莲子草水溶性化感物质抑制了受体植物的有丝分裂,干扰了植物细胞DNA的正常修复,破坏了植物细胞纺锤丝的结构与功能,进而导致染色体畸变,使微核率上升,细胞中出现了染色体片断,滞后染色体,染色体桥等异常情况。本研究结果表明,空心莲子草具有较强的化感作用,通过改变植物细胞的膜透性和功能,影响植物体的光合作用过程、抑制细胞的有丝分裂、干扰DNA损伤的正常修复等,进而影响到植物的种子萌发和幼苗生长。空心莲子草的化感作用可能是其成功入侵的机制之一。更多还原

【Abstract】 A perennial herbaceous species,alligator weed(Alternanthera philoxeroides Griseb ) that is classified family Amaranthaceae belongs to Alternanthera genus. It is a invasive plant that has spread thoughout our country and has been harm to agriculture economy, entironment and biodiversity. It is important significance that studied the mechanism of the allelopathy and heredity toxicity of this species to effectively control the invasive plant.In this study, we tested the allelopathic effects of different concentrations aqueous upground organ and underground organ extracts of A. philoxeroides on seed germination, seedling growth and some physiological process of three receptor plants such as lettuce (Lactuca sactiva L.), whea(tTriticum aestivum L.)and rape (Brassica. napus L)by biassay. The result showed that the aqueous extract of A. philoxeroides observably inhibited the final germination and germination speed of lettuce and rape. The allelopathic effect of A. philoxeroide on seed germination of receptors mainly exhibited that delayed seed germination. And the aqueous extracts of A. philoxeroides markedly promoted growth the upground growth of lettuce, but have no significant effect to underground growth of lettuce. Low concentration aqueous extract of A. philoxeroides promoted seedling growth of wheat ,and high concentration aqueous underground organ extract inhibited seedling growth of wheat. The aqueous extract of A.philoxeroides commonly promoted seedling growth of rape. MDA content of receptors increased and the SOD active and POD active observably changed by aqueous extract s of A. philoxeroides showed that receptors were stressed and their structure and function of membranes were damaged in a certain extent by water-solubility allelopathic matter of A. philoxeroides. The water-solubility allelopathic matter affected the photosynthesis of receptors by influencing content of chlorophyla, chlorophylb and carotinoid. The allelopathy of A.philoxeroides was concentration dependent, increasing with the increase of concentration. The allelopathy of the underground organ was biger than that of upground organ. The sensitivity of the receptors to the allelopathy of A.philoxeroides changed with species and were rape﹥lettuce﹥wheat.The micronucleus test technique of Vicia fabra cells was first applied to study the allelopathic effect of A. philoxeroides. The results showed that t aqueous extract s of A. philoxeroides significant inhibited mitosis,disturbed the DNA repaired of receptors cells and damaged structure and function of spindle. So the rate of micronuclei rised and Bhromosome Bridge, chromosome break and chromosome lag appeared. The results of this present indicated that water-solubility Allelopathic matter of A.philoxeroides was genotoxic.As a result, A. philoxeroides had very strong allelopathy. It could influence the photosynthesis process, changed the cell membrane’s permeability and function, inhibited the mitosis and disturb the DNA repaired, more affected seed germination and seedling growth. So allelopathy of A.philoxeroides Griseb was one of potential causes of successful invasion.更多还原