外来入侵植物喜旱莲子草在水淹逆境中的氧获取机制研究

喜旱莲子草是在我国有广泛分布的外来入侵植物，具有很强水淹耐受能力，其高耐淹性极大提高了喜旱莲子草的环境适应能力和入侵能力。在水淹环境中低氧胁迫是所有受淹植物无法避免的问题，喜旱莲子草具有优良耐淹能力提示其在水淹逆境中可能具有有效的氧获取机制。植物在水淹环境中有两种可能的获氧方式，一是通过自体的光合组织光合产氧，二是从环境中获取氧。本项目拟对处于水淹环境中的喜旱莲子草的叶和茎水下光合特性、不定根发生空间格局及其吸氧效率、叶和茎表面气膜形成及其对氧获取的影响、非连续髓腔通气组织输氧能力进行研究，以阐明受淹喜旱莲子草是否可以通过水下光合作用自身产氧和从环境中获取氧来提高体内氧含量水平以抵御水淹低氧胁迫，明确喜旱莲子草在水淹逆境中的氧获取途径和机制。本研究有助于揭示喜旱莲子草具高耐淹能力和入侵能力的内在原因，为入侵植物入侵机理研究和入侵植物控制提供科学依据，并有助于深化植物水淹耐受理论研究。

Alternanthera philoxeroides is an alien invasive plant species growing extensively in China. The species is highly tolerant of flooding and submergence, which enhances its environment adaptability and invasiveness. All plants have to confront hypoxia stress when they are submerged, the high submergence tolerance possessed by A. philoxeroides implies that this species likely have effective pathways to acquire oxygen. Upon submergence, plants have two possible ways to get oxygen, the first is to get the oxygen produced by submerged photosynthetic tissues in underwater photosynthesis, the second is to obtain oxygen from the surrounding environments. In this project, the underwater photosynthetic capacity of submerged leaves/stems, spatial pattern of adventitious roots formation and its effects on oxygen acquisition, gas films formation on leaf/stem surfaces and its effects on oxygen acquisition, oxygen transport capacity of discontinuous pith cavity are to be investigated, so as to unravel whether submerged A. philoxeroides can acquire oxygen from its surrounding environments and from underwater tissue photosynthesis to resist hypoxia stress, and to reveal the oxygen acquisition mechanisms of A. philoxeroides upon submergence. The study will help to elucidate why A. philoxeroides has high flooding/submergence tolerance and invasiveness, and help to deepen our understanding on the mechanisms of plant flooding/submergence tolerance.