接种根瘤菌对台湾相思生长和抗旱能力的影响

Inoculation of Rhizobia Strains Enhance the Growth and Drought Tolerance of Acacia confusa

干热河谷地区是西南地区生态环境最脆弱的地区之一,而豆科树种是该地区能天然更新的少数树种之一,共生的根瘤菌及其与树种耐旱性的关系值得研究。本研究选取能进行共生固氮的台湾相思树种与野外分离到的相思树种根瘤菌进行共生结瘤试验,并进行干旱模拟实验,通过生物量测定,显微结构观察,揭示该地区台湾相思树种干旱条件下的生长规律,并对能够与相思树种共生结瘤的根瘤菌进行分子鉴定和多样性分析,为发掘优良的根瘤菌种质资源提供理论依据。结果发现,在各PEG质量浓度梯度下,与根瘤菌共生结瘤的台湾相思幼苗比未接种过根瘤菌没有结瘤的台湾相思幼苗表现出更强的耐旱能力;通过分子鉴定得出,15株供试菌株分别属于快生根瘤菌属(Rhizobium)、中慢根瘤菌属(Mesorhizobium)和慢生根瘤菌属(Bradyrhi-zobium),说明干热河谷地区台湾相思树种根瘤菌有着较为丰富的多样性。因此推论台湾相思与根瘤菌形成共生系统有助于其在干热河谷生存和天然更新。

The Dry-hot Valley is the most ecological vulnerable areas in southwest China.Legumes trees are the few trees that can survival and naturally regenerate in the area.The relevance of rhizobia symbiosis to drought tolerance of legume needs further study.Rhizobia that were isolated from wild nodule of Acacia richii were inoculated onto the same host seedlings.When the nodules were observed,the seedlings were subjected into drought experiment with different PEG mass concentration gradients.The biomass measurement and microscope observation were carried out,in order to understand the growth performance of Acacia confusa and mycrobial symbiont under drought stress.The 16sRNA sequence detect was also carried out to identify the species of strains,which may help for screening the potential superior strains.The result indicated that seedlings with inoculation had higher drought tolerance than control with no inoculation.16sRNA sequence detection proved that the selected 15 strains belong to Rhizobium,Mesorhizobium and Bradyrhizobium respectively,indicating it has a rich diversity of nodulation strains that can form symbiosis with A.confusa in dry hot valley.Thus it is inferred that natural regeneration and survival of A.confusa may be relevance to symbiosis with nodulation strains.