西北荒漠带细枝岩黄耆AM真菌与DSE真菌时空分布研究

为探明细枝岩黄耆Hedysarum scoparium根系丛枝菌根真菌（arbuscular mycorrhizae,AM）和深色有隔内生真菌（dark septate endophytes,DSE）定殖特征及其生态地理分布,充分理解菌根共生体在植物生长和植被恢复中的功能,本研究连续3年采集我国西北荒漠带不同样地细枝岩黄耆0-30cm土层土壤样品和根样,不同样地细枝岩黄耆均能被AM和DSE侵染,形成AM典型结构菌丝、泡囊和丛枝,DSE典型结构深色有隔菌丝和微菌核。细枝岩黄耆根系AM真菌定殖高于DSE定殖,但极端干旱条件下DSE定殖优于AM真菌定殖。AM真菌定殖率不同年际间表现为2016年最高,同一年份不同样地,除乌海、沙坡头样地,菌丝定殖率自东向西呈降低趋势。DSE真菌定殖率,在同一样地不同年份：乌海样地2016年定殖率显著高于2015年和2017年,在同一年份不同样地：2015年沙坡头样地DSE菌丝定殖率、总定殖率显著高于其他样地,而2016、2017年鄂尔多斯样地最高。NMDS分析结果显示,AM和DSE真菌定殖不同年际间差异显著。相关性分析表明,AM真菌定殖率与DSE定殖率显著正相关;土壤温度与AM定殖显著负相关;有机碳、速效磷、磷酸酶、湿度与AM定殖显著正相关;DSE菌丝定殖率、定殖强度仅与酸性磷酸酶正相关。本研究比较分析西北荒漠带不同样地AM和DSE定殖与土壤因子的相关性,有助于充分理解菌根共生体在植物生长和植被恢复中的功能和意义。

Spatial and temporal distribution of arbuscular mycorrhiza fungi and dark septate endophytes in Hedysarum scoparium from northwest desert belt

Colonization characteristics and ecological geographical distribution of Hedysarum scoparium root arbuscular mycorrhizae and dark septate endophytes, as well as the functions of mycorrhizal symbiont in plant growth and vegetation restoration were investigated. Soil and root samples of 0-30cm soil layer of different sampling sites in the desert belt of northwest China were collected for three consecutive years (2015-2017). H. scoparium was naturally infected by AM fungi and DSE in different sampling sites, forming typical AM structure with hyphae, vesicles and arbuscules, and typical DSE structure with dark septate hyphae and microsclerotia. The colonization of AM was higher than that of DSE, but DSE colonization prevailed over AM fungal colonization under extreme drought conditions. The colonization rate of AM was the highest in 2016 of observational years. In the same observational year, except for Wuhai and Shapotou sample plots, the hyphal colonization rate of AM fungi showed a decreasing tendency from east to west in different sample plots. The colonization rate of DSE was significantly higher in Wuhai in 2016 than that in 2015 and 2017. The DSE hyphal colonization rate and total colonization rate were significantly higher in the Shapotou than those in other sampling sites in 2015, while the colonization rate in Ordos sampling site was the highest in 2016 and 2017. The results of NMDS analysis showed that there were significant differences between AM and DSE colonization in different years. Correlation analysis showed that there was a significant positive correlation between colonization rate of AM and that of DSE. Soil temperature was negatively correlated with AM colonization, while organic carbon, available phosphorus, phosphatase and humidity were positively correlated with AM colonization, and DSE hyphal colonization rate and colonization intensity were solely positively correlated with acid phosphatase. This study is helpful to further understand the function of mycorrhizal symbiont in plant growth for vegetation restoration in the northwest desert.