3株紫花苜蓿内生根瘤菌功能差异性分析

Analysis of functional differences among three Medicago sativa endophytic rhizobial strains

以3株紫花苜蓿(Medicago sativa)内生根瘤菌株(LP3、WLP2和WLG1)为材料,进行抗逆和促生能力研究,并采用试管砂培法对WL168HQ苜蓿(M.sativacv.WL168HQ)进行接种试验,以不含根瘤菌的培养液为对照,分析菌株的共生固氮能力。结果表明,菌株WLP2能耐受除红霉素和庆大霉素外的所有抗生素≥300μg·mL^(-1);能在6%NaCl、pH 5~11和温度8~40℃的环境下生长,对盐、pH和温度的适应范围广;能溶解有机磷和无机磷,分泌IAA能力强。菌株WLG1接种,单株结瘤数、地上干重和地下干重显著高于对照处理(P<0.05),分别比对照增加了208.16%、72.35%和122.33%;单株有效根瘤重、根长和单株叶片数明显高于对照处理,分别比对照高了6.68%、9.57%和53.59%。综上所述,菌株WLP2对抗生素、盐、pH和温度的抗性以及促生能力较强,菌株WLG1对WL168HQ苜蓿接种效果最佳,共生固氮能力强。

Three endophytic rhizobial strains（Sinirhizobium meliloti,LP3,WLP2,and WLG1）were inoculated onto Medicago sativa ‘WL168 HQ＇grown on sterilized sand in glass test tubes to analyze their symbiotic ability.The control was treated with cultural liquid without rhizobial strains.Strains were also studied to evaluate stress tolerance and growth promotion.Results showed that endophytic rhizobial strain WLP2 could tolerate all tested antibiotics（≥ 300μg·mL^-1）except for erythromycin and gentamycin.It could grow in a medium containing 6% NaCl and with pH 5-11,and could tolerate a temperature range of 8-40℃.This strain was able to dissolve organic phosphate（EYPC）and inorganic phosphate[Ca3（PO4）2],and was capable of secreting indole acetic acid as well.The symbiotic effects of strain WLG1 were optimal.The nodule numbers,along with above-ground and below-ground dry weight of plants inoculated with WLG1,increased significantly（P〈0.05）compared with the control,with increases of 208.16%,72.35%,and 122.33%,respectively.Effective nodule weight,root length,and leaf number of plants inoculated with WLG1 increased by 6.68%,9.57%,and 53.59% compared with the control,respectively.Altogether,endophytic rhizobial strain WLP2 presented high antibiotic,salt,pH,and temperature resistance and had a strong ability to promote plant growth,while strain WLG1 showed better inoculation effects on M.sativa ‘WL168 HQ＇and strong symbiotic nitrogen fixation.