紫外辐射对灯盏花附生、内生细菌数量的影响及机理

采用大田研究方法,模拟5.0kJ·m~(-2)紫外辐射(UV-B,280～315nm)增强对灯盏花Erigeronbreviscapus附生、内生细菌数量、优势种群以及类黄酮、游离氨基酸、可溶性蛋白、淀粉和可溶性糖含量的影响.UV-B辐射极显著减少灯盏花苗期叶和花期根与叶附生细菌数量(p<0.01),显著减少灯盏花果熟期根与叶附生细菌数量(p<0.05).极显著减少灯盏花苗期根与叶和花期叶与茎及果熟期茎内生细菌的数量,果熟期根内生细菌数量显著增加.灯盏花附生细菌优势种群为芽孢杆菌Bacillus和欧文氏菌Erwinia,内生细菌优势种群为芽孢杆菌;UV-B辐射可导致灯盏花附生和内生细菌优势种群数目减少.UV-B辐射还会使灯盏花生理指标发生变化,直接导致灯盏花附生细菌数量的减少,可溶性糖、游离氨基酸和可溶性蛋白含量与附生细菌数量呈显著正相关(p<0.05).UV-B辐射增加灯盏花各部位类黄酮含量,间接影响灯盏花内生细菌数量,根类黄酮含量与内生细菌数量呈极显著正相关(p<0.01).

Effects of UV-B radiation on quantity of epiphytic bacteria, endophytic bacteria and physiological mechanism of Erigeron breviscapus

Field studies were conducted for analyzing dominant populations, quantities of epiphytic bacteria and endophytic bacteria, and the contents of flavonoid, free amino acid, soluble portion, soluble sugar and starch of Erigeron breviscapus with enhanced ul-traviolet-B radiation(5.0 kJ·m~(-2)). The quantities of the epiphytic bacteria in leaf of seedling, root and leaf in flowering stages were decreased significantly with UV-B radiation(p<0.01), as well as in root and leaf of maturity stage(p<0.05). UV-B radiation significantly reduced the quantities of the endophytic bacteria in root and leaf of seedling, leaf and stem in flowering stages, whilst significantly increased in root of maturity stage. The dominant populations of epiphytic bacteria were Bacillus and Erwinia. The dominant population of endophytic bacteria was Bacillus. UV-B radiation decreased the amount of the dominant populations of epiphytic and endophytic bacteria. The quantities of epiphytic bacteria decreased due to changes of physiological metabolish with UV-B radiation. Significantly positive relationships were observed between the contents of free amino acid, soluble portion, soluble sugar and the quantity of epiphytic bacteria(p<0.05). UV-B radiation increased flavonoid contents in each parts of Erigeron breviscapus. Significant positive correlation was observed between flavonoid contents and the quantity of endophytic(p<0.01).