肠杆菌FYP1101对盐胁迫下小麦幼苗的促生效应

摘要

[背景]中国盐碱地面积大、分布广、类型丰富,主要分布在东北、西北、华北及滨海地区,近年来的研究表明通过生物治理方式接种植物根际促生菌可提高植物对盐胁迫的抗性,从而加速盐碱地治理.[目的]初步揭示肠杆菌(Enterobacter sp.) FYP1101对盐胁迫下小麦幼苗的促生效应和机理,以期为该菌株的田间应用提供理论依据.[方法]基于涂布划线技术,以植酸磷培养基进行分离纯化,分别以Ashby培养基、无机磷培养基进行具有固氮、解无机磷能力细菌的初筛,之后对纯化所得细菌进行固氮、解植酸磷、解无机磷、产铁载体、产1-氨基环丙烷-1-羧酸(ACC)脱氨酶、产吲哚乙酸(IAA)能力的分析;基于16S rRNA基因序列对FYP1101做初步分类鉴定;设置3种处理(施加含FYP1101的颗粒菌肥,FP;施加不含菌的空载体颗粒,NK;颗粒菌肥和空载体颗粒都不施加的空白处理,CK),采用盆栽试验分析不同处理下的盐胁迫小麦生长性状及其根际土理化性质变化.[结果]共分离得到96株菌,其中一株编号为FYP1101的菌株耐盐性达8％,且具有较强的固氮能力[固氮酶活性为2.59 nmol C2H4/(h·mg蛋白)]、解植酸磷能力(2.70 μg/mL)、解无机磷能力(4.29 μg/mL)、产铁载体能力(D/d为2.88)、ACC脱氨酶活性[7.32 μtmol 6c-丁酮酸/(h·mg蛋白)]、产IAA能力(24.93 mg/L);基于16S rRNA基因序列,将FYP1101鉴定为Enterobacter属的菌株;FP相比NK和CK处理,显著提高了盐胁迫下小麦的叶绿素含量及地上和地下的生物量(提高约19％-54％),显著增加了根长(增幅约46％);根际土有机质和速效氮含量也显著提高,提高约52％-98％,根际土pH略降低(0.12和0.17),盐度升高约40％.[结论]Enterobacter sp.FYP1101具有多种植物促生特性,可显著影响盐胁迫下小麦幼苗根形态的建成,提高根际土营养、降低小麦对盐的吸收,促进小麦幼苗生长,在促进植物适应逆境胁迫方面具有良好的应用潜力.%[Background] Saline-alkali land area in China is big,wide distributed and diversified,which is mainly distributed in northeast,northwest,north and coastal areas in China.The research in recent years has shown that the bioremediation by inoculation of PGPR can improve resistance of plants to salt stress,increasing the saline-alkali land management.[Objective] To preliminarily discover the growth promoting effect and mechanism of Enterobacter sp.FYP1101 on wheat seedling under salt stress,and to provide the theoretical basis for the field application of the strain.[Methods] On medium of phytate-phosphorus,using spread and streak plating technique to isolate;on Ashby medium and inorganic-phosphorus medium,the bacteria of nitrogen-fixation and inorganic-phosphorus-solubilizing were screened preliminarily,then analyzed their abilities for nitrogen-fixation,phytate-phosphorus-solubilizing,inorganic-phosphorus-solubilizing,siderophoreproducing,1-aminocyclopropane-l-carboxylate (ACC)-deaminase-producing and indole acetic acid (IAA)-producing;16S rRNA gene was applied to preliminarily and taxonomically classify the strain FYP 1101;plotted wheat under salt stress and conducted 3 treatments (treatment FP,adding particle microbial fertilizer containing FYP1101;treatment NK,adding null particle carrier containing no bacterial inoculant;treatment CK,neither particle microbial fertilizer nor null particle carrier added),then compared the shifts of the growth traits and physiochemical properties of rhizosphere soil of wheat seedlings under salt stress between different treatments.[Results] A total of 96 rhizospheric strains were isolated;one isolate designated by FYP1101 has salt tolerance up to 8％,and showed strong abilities of nitrogen-fixation (nitrogenase activity of 2.59 nmol C2H4/(h·mg protein)),phytate-phosphorus-solubilizing (2.70 μg/mL),inorganic-phosphorus-solubilizing (4.29 μg/mL),siderophore-producing (D/d ratio of 2.88),ACC-deaminase-activity (7.32 μmol a-butanone/(h·mg protein)) and IAA-producing (24.93 mg/L);based on 16S rRNA gene sequence,strain FYP1101 was classified into the genus of Enterobacter;Compared with NK and CK,the wheat inoculated by FP under salt stress showed chlorophyll content and biomass of overground and underground increased markedly (with increments of 19％-54％) and root length also increased markedly (with increments of 46％);the concentration of rhizospheric organic matter and available nitrogen were improved by about 52％-98％,whereas pH slightly decreased (0.12 and 0.17 units) and salinity increased about 40％.[Conclusion] Enterobacter sp.FYP 1 101 has many kinds of plant growth promoting traits.The strain can significantly affect the root establishment of wheat seedling under salt stress,improve the content of nutrition in rhizosphere soil,reduce the absorption of wheat for salt and promote the growth of wheat seedling.This suggests that Enterobacter sp.FYP1101 has a great potential in improving the adaptation of plant to stress.