【作者】 范雪涛；

【导师】 马丹炜；

【作者基本信息】 四川师范大学 ， 细胞生物学， 2008， 硕士

【摘要】 辣子草(Galinsoga parviflora Cav.)原产南美洲,1915年在我国云南和四川等地发现,是一种危害较严重的外来入侵种。研究其在逆境条件下的生理适应机制和化感作用对于有效预警和治理该入侵种具有十分重要意义。本研究采用人工设置温度梯度和自然干旱方法,研究了在不同环境胁迫条件(温度和干旱)下辣子草抗氧化酶、脯氨酸、可溶性蛋白和丙二醛(MDA)的变化。结果表明:在10℃～30℃范围内辣子草抗氧化酶系统变化趋势不一致,脯氨酸随温度升高而升高,可溶性蛋白随温度升高降低,MDA含量未出现显著性变化;在5℃、35℃和45℃胁迫下抗氧化系统受到损伤,MDA含量显著上升;在干旱胁迫条件下,抗氧化酶系统先上升,后下降,MDA含量在干旱胁迫后期含量显著上升。应用Fuzzy方法,对辣子草抗氧化酶在2种逆境不同水平胁迫的动态进行综合评价,认为辣子草生长的最适温度在15～30℃间,对低温环境也有一定的适应能力,对干旱环境的适应性较差。采用生物测定法,研究辣子草水浸提液对水稻(Oryza sativa L.)、小麦(Triticum aestivum L.)和油菜(Brassica napus L.)种子萌发和幼苗生长以及抗氧化系统的影响,结果表明辣子草具有化感作用。辣子草水浸提液对受体植物的种子萌发和幼苗生长整体表现为抑制效应,这种抑制效应随着水浸提液浓度的升高而增大;在辣子草水浸提液作用下,油菜幼苗活性氧清除系统和细胞膜通透性遭到破坏,保护酶系统失衡,随着水浸提液的作用时间延长油菜叶片内的SOD活性和MDA含量表现为先升高后降低的趋势,POD活性的变化则是先下降后持续升高。采用蚕豆根尖细胞微核技术研究低温胁迫前后辣子草化感作用的变化,结果表明:温度胁迫改变了辣子草水浸提液对蚕豆(Vicia faba L.)根尖细胞的有丝分裂指数、微核率和畸变率的化感效应。低温胁迫前,辣子草水浸提液使蚕豆根尖细胞有丝分裂指数下降,微核率和畸变率增大;低温胁迫后,辣子草水浸提液的化感效应发生变化,对有丝分裂指数的影响表现为“低浓度促进,高浓度抑制”效应,而微核率和畸变率较胁迫前显著增大。低温打破代谢的协调性,在温度胁迫下,辣子草可能通过增加体内化感物质的数量和种类,以增加对矿物质和水分的吸收,并向环境释放化感物质,抑制和排挤周围的其他植物,增强其竞争能力。更多还原

【Abstract】 Galinsoga parviflora Cav(.gallant-soldier), native to South America, was first recorded in Yunnan and Sichuan in 1915. Now it has already become an invasive plant in China. Knowledge of the physiological response in stressful environments and allelopathy are very useful in determining the invasive mechanism of this plant.By using the artificial constitution temperature steps and natural dry method in this paper, the varieties of proline, soluble protein, antioxidant enzymes and monodehydroascorbate (MDA) in G. parviflora were studied by environmental stresses such as temperature and drought. The result showed that changes of antioxidant enzymes of G. parviflora were difference from 10℃to 30℃while MDA was found no significant changes and antioxidant enzymes were damaged and MDA contents sharply increased at 5℃,30℃and 35℃. For the drought treatments, the antioxidant enzymes increased at the beginning and decreased later, while MDA increased only at later stage. These results indicated that G.parviflora had a better adaptation to low temperature than the heat and drought stress. Using Fuzzy synthetic evaluation, we evaluated the developments of the antioxidant enzymes, finding that 15-30`C was the optimum temperature for the growth of G.parviflora.By using bioassay method, the allelopathy of aqueous extracts of the G.parviflora. to seed germination, seedling growth and antioxidant enzymes of rice (Oryza sativa L), wheat (Triticum aestivum L)and rape (Brassica napus L)were studied. The results showed the allelopathic effect of gallant-soldier. High concentration aqueous extracts inhibited evidently seed germination and the seedling growth, and this effect was concentration dependent, increasing with increase of aqueous extracts concentration. Under the effect of the aqueous extract, the active oxygen metabolism system and cell membrane permeability were destroyed, and the balance of the protective enzyme system was broken. With the action time of aqueous extracts prolong, the SOD active and the content of MDA of rape in leaf increased at the beginning and decreased later, but the POD active had an opposite tendency.The effect of low temperature stress on allelopathy of G.parviflora was studied by using micronucleus test in Vicia faba root tip cell. The results showed that allelopathic effects of the aqueous extracts of G.parviflora on mitotic index, micronucleus and aberration rates were changed under low temperature stress. Mitotic index decreased, while micronucleus and aberration rates increased by the aqueous extracts of G.parviflora before low temperature stress. After the low temperature stress, however, mitotic index changed in accordance with the concentration of the aqueous extracts of G.parviflora low aqueous extracts concentration of the weed led to mitotic index increase, and high concentration resulted in mitotic index decrease. In addition, micronucleus and aberration rates were significantly higher than those before the stress. Low temperature stress disturbed metabolic cooperation. When G. parvi- flora was stressed by low temperature, on the one hand, this species could enhance absorbing ability of root on mineral substance and water by increasing amount and type of allelopathic substance, on the other hand, it could strengthen its competitive ability by releasing allelopathic substance into the environment to inhibit and supplant other plants.更多还原