基于DGGE研究喀斯特金橘接种AMF对根际细菌多样性和植株生长的影响

该研究分别以喀斯特地区的酸性土和石灰土为盆栽基质,对金橘分别接种摩西管柄囊霉(Funneliformis mosseae,F.m)或幼套近明囊霉(Claroideoglomus etunicatum,C.e),采用变性梯度凝胶电泳(DGGE)等技术研究AMF对金橘根际细菌群落多样性及植株生长的影响。结果表明:与不接种处理相比,同类型土中分别接种C.e或F.m,金橘根际菌根侵染率相关指标(F、m、v)值均为C.e处理的最高,C.e或F.m处理后金橘根际土壤中蔗糖酶、酸性磷酸酶、蛋白酶及脲酶活性均显著提高。其中,蛋白酶和脲酶活性变化为石灰土中各处理酶活性值高于酸性土,蔗糖酶和磷酸酶活性变化则为酸性土中各处理酶活性值高于石灰土,差异均达显著水平(P0.05);两种土壤中上述四种土壤酶活性均为C.e处理的值最高;接种C.e或F.m后,金橘根际土壤细菌的DGGE图谱中,DNA条带数增多,其细菌丰富度(R)、多样性(H)和均匀度(E)指数均比不接种处理高,三种指数值均以C.e处理的最高。细菌DNA优势条带序列分析结果表明:与优势细菌同源性最高的大部分为不可培养细菌,包括酸酐菌属、变形杆菌属、根瘤菌属和放线菌属等,相似性均大于97%。此外,接种后,金橘整株生物量比不接种处理显著提高,而酸性土中接种C.e处理的金橘生物量最高。综上所述,C.e和F.m均能与金橘建立良好的共生关系,且C.e对金橘根系的侵染效果更好。

Effects of Fortunella margarita inoculated with AMF on rhizospheric bacterial community diversity based on DGGE

To overcome the soil infertility and poor crop output problem of karst region, we chose Funneliformis mosseae(F.m)and Claroideoglomus etunicatum(C.e)as AMF inoculants and two types of soil in karst region as potted matrix, the bacterial community diversity and growth of Fortunella margarita were investigated by PCR-DGGE(denaturing gradient gel electrophoresis)technique and other conventional approaches. The results were as follows: Comparing to no AM fungi treatment, the colonization rate of root system of F. margarita such as F, m, v inoculated with either C.e or F.m treatment increase significantly. No matter in either type of soil, C.e treatment are the highest. In addition, rhizospheric soil enzyme activities including invertase, phosphatase, protease and urease with either C.e or F.m treatment increase significantly. Among them, activities of protease and urease are the highest in lime soil(LS), and that of invertase and phosphatase in acid soil(AS)are higher than that in LS, the differences are significant with each other(P<0.05). Either in AS or LS, the four kinds of soil enzyme activities with C.e are the highest. In terms of bacterial diversity, the bands number of bacterial DNA with AMF of DGGE profile enriched, and the index of richness(R), diversity(H)and evenness(E)with AMF are higher than no AMF treatment. No matter in either type of soil, value of R, H and E with C.e are the highest. Additionally, based on the results of sequence analysis to DNA dominant bands of DGGE profile, all dominant bacterial strains are phylogenetically closen to uncultured microbes, including Acidobacterium, Proteus, Rhizobium and Actinomyce, the similarity of each is above 97%. Moreover, comparing to no AM fungi treatment, biomass of Fortunella margarita inoculated with either C.e or F.m treatment increases significantly, C.e treatment are the highest in AS. In conclusion, comparing to F.m, C.e represents better efficiency for F. margarita in karst region. AMF can enhance activities of four rhizospheric soil enzyme, stimulated diversities of soil bacteria population. As the result, plant biomass increase. It provides the information for improving growth of F. margarita by facilitating the conversion and dynamics of nutrients such as C, N, P and others.