金钗石斛IAA内生细菌筛选及对干旱胁迫下玉米种子萌发的影响

摘要

The indole-3-acetic acid (IAA) producing endophytic bacteria were isolated and screened from Dendrobium nobile Lindl.Under the condition of dought stress stimulated with different concentration of PEG-6000,the maize seed germination were studied after treating with the IAA-producing strains.The results showed that a total of 645 strains endophytic bacteria were isolated from D.nobile Lindl.,and 63.4％ of the strains have the ability to produce IAA,using with the salkowskis reagent method,9 strains were screened,which produced 12.8-34.5 mg/L IAA and showed a higher ability of IAA production.Based on 16 S rRNA gene sequence analysis,these endophytic bacteria were identified as Bacillus sp.and Paenibacillus sp..The IAA-producing endophytic bacteria were fermentated and the supernatant were used to soak the maize seeds.Under the condition of absence PEG or drought stress of 5 ％,10 ％ and 15 ％ PEG,the germination rate of the seeds treated with the endophytic bacteria were less than or equal to the control's.Howerer,soaking with the IAA-producing endophytic bacteria could elliminate the high drought stress effect of the maize seeds.Under the condition of 20 ％ PEG,there are 7 strains can significantly promote the seed germination,the germination rate of endophytic bacteria soaking seeds were increased by 4.7 ％-13.3 ％ compared with the control.Under the condition of 25 ％ PEG,the germination rate of the seeds treated with the endophytic bacteria LJYPD 10 was increased by 5.3％ than the control’s.%从金钗石斛植株中分离并筛选产吲哚乙酸(IAA)的内生细菌,研究在不同浓度PEG-6000模拟的干旱胁迫条件下,产IAA内生菌发酵上清液浸种处理对玉米种子萌发的影响.从金钗石斛分离出645株内生细菌,通过salkowskis法筛选表明,63.4％的内生菌具有分泌IAA的能力,其中有9株菌分泌量较高,分泌量为12.8～34.5 mg/L.基于16SrRNA基因序列分析,初步鉴定它们为芽孢杆菌属(Bacillus)和类芽孢杆菌属(Paenibacillus)细菌.将内生菌发酵上清液浸种处理玉米种子,在未加PEG以及5％、10％和15％ PEG的干旱胁迫条件下,其种子萌发率与对照组的相当或降低.但部分产IAA内生菌浸种处理可缓解高度干旱胁迫作用:在20％ PEG条件下,有7株内生菌浸种处理后玉米种子萌发率显著提高,较对照组提高了4.7％～13.3％;25％ PEG条件下,内生菌LJYPD 10处理的玉米种子萌发率比对照组显著提高了5.3％.