Abstract: In order to determine the effect of Erwinia sp. DE2,the dominant pathogen of pear fire blight,on the seedling growth of Alfalfa (Medicago sativa),Melilotus suavcolen (Melilotus officinalis) and Astragalus adsurgens (Astragalus adsurgens),this experiment used a growth bottle germination test to measure the effects of DE2 on the growth and physiological indicators of three leguminous forage seed seedlings. The results showed that the germination potential,germination rate and germination index of three leguminous forages after inoculation were lower than those of the control group,and the germination index of rhinoceros and alfalfa were significantly lower than those of the control group (P<0.05);The root length of the three forages was significantly lower than that of the control (P<0.05). After inoculation with DE2,the activities of Superoxide dismutase (SOD),Catalase (CAT),Glutathione peroxidase (GSH-Px) and the contents of Superoxide anion (O^-₂),Hydrogen peroxide (H₂O₂),Malondialdehyde (MDA) and Soluble proteinsp in three kinds of legumes were all changed in different degrees,among which the SOD activities of three kinds of legumes increased compared with the control,and CAT activities significantly increased (P<0.05),The content of O^-₂ and soluble protein decreased,while the content of H₂O₂ in Mclilotus suavcolen and Astragalus adsurgens increased. To sum up,after being infected by DE2 strain,the three leguminous forages had started their own defense mechanism,but they could not resist the damage caused by DE2.This study provided a scientific basis for the evaluation and comprehensive control of newly discovered pathogenic microbiota in forest and grass ecosystem.

Key words: Dominant pathogenic bacterium of pear fire blight, Legume forage, Seedling growth, Physiological index

摘要： 为明确梨火疫病的优势致病菌欧文氏菌DE2(Erwinia sp. DE2)对紫花苜蓿(Medicago sativa)、草木犀(Melilotus officinalis)和沙打旺(Astragalus adsurgens)3种豆科牧草幼苗的生长影响,本试验采用生长瓶萌发试验,测定了DE2对3种豆科牧草种子幼苗生长和生理指标的影响。结果表明接种DE2后的3种豆科牧草的发芽势、发芽率和发芽指数均低于对照组,其中草木犀和紫花苜蓿的发芽指标显著低于对照(P<0.05);3种牧草的根长都显著低于对照(P<0.05)。接种DE2后引起了3种豆科牧草超氧化物歧化酶(Superoxide dismutase,SOD)、过氧化氢酶(Catalase,CAT)、谷胱甘肽过氧化物酶(Glutathione peroxidase,GSH-Px)的活性和超氧阴离子(Superoxide anion,O^-₂)、过氧化氢(Hydrogen peroxide,H₂O₂)、丙二醛(Malondialdehyde,MDA)和可溶性蛋白(Soluble protein,SP)的含量均有不同程度的变化,其中3种豆科牧草的SOD活性相比对照均有增加,CAT活性显著增加(P<0.05),O^-₂含量和可溶性蛋白的含量均减少,而草木犀与沙打旺的H₂O₂含量却增加。综上,3种豆科牧草在受到DE2菌株侵染之后,虽启动了自身防御机制但均无法抵御来自DE2造成的伤害。本研究为评估和综合防控林草系统中新发病原微细菌提供科学基础。

关键词: 梨火疫病优势致病菌, 豆科牧草, 幼苗生长, 生理指标