不同抗病性茄子根系分泌物对黄萎菌的化感作用

Allelopathy of the root exudates from different resistant eggplants to verticillium wilt(Verticillium dahliae Kleb.)

以不同抗病性茄子为试材,即抗病类型Solanum tor、S.sis,耐病类型立原紫茄,感病类型西安绿茄,研究了不同茄子品种抗黄萎病特性,根际微生物结构与黄萎菌数量的变化,茄子根系分泌物对黄萎菌的化感作用,并利用GC-MS对根系分泌物的成分进行了鉴定。结果表明:抗病类型的根系分泌物既可以直接影响黄萎菌的生长、发育,又可以通过调节土壤微生物种群结构间接影响黄萎菌的生长,达到抗病效果。而感病类型则正相反。推断这可能是因为抗病类型根系分泌物中存在醇类、胺类、吡喃类、芴类等特异物质,而感病类型根系分泌物中酮类、酚类、酯类、酚酸类物质种类或含量较高。

Verticillium Wilt is one of the most destructive deceases of eggplant in China.Up to now,the allelochemicals from eggplant root exudates have been found in relation to the outbreak of Verticillium Wilt.However,the relationship between root exudates from different eggplant cultivars and their resistance to Verticillium Wilt has not been determined.Four eggplant cultivars were inoculated with Verticillium Wilt（Verticillium dahliae Kleb.） to assess their resistance to Verticillium Wilt in the present study.The results showed that Solanum tor and S.sis were resistant,＂Liyuanziqie＂ was tolerant,and ＂Xi′anlvqie＂ susceptible.The variation of main microorganism and Verticillium dahliae in rhizospheric soil,the allelopathy of root exudates to mycelium growth of Verticillium dahliae and the chemical substances of root exudates from eggplant cultivars with different resistance to Verticillium Wilt were investigated in this experiment.The experiment results exhibited that the root exudates of resistant and susceptible types inhibited the mycelium growth of Verticillium dahliae,while the susceptible one promoted the mycelium growth,during the whole incubation period.But the influence was waned gradually with time elapsing.The number of Verticillium dahliae sclerotia in the soils of all cultivars was increased with eggplant growth.The resistant types showed significantly lower population of Verticillium dahliae at each growth stage compared to the susceptible one.These conclusions were consistent with the disease incidence and the disease index of Verticillium wilt in the field.The root exudates of resistant types could not only affect the growth and development of Verticillium dahliae,but also influence Verticillium dahliae indirectly through regulating soil microbial community composition.With the reduction of bacterium,the population of total microorganisms（including bacterium,actinomyces and fungi） in rhizophere decreased,especially ＂Xi′anlvqie＂.Comparing with the eggplants without inoculation,the population of actinomyces in rhizosphere of ＂Xi′anlvqie＂ phased down,the number of actinomyces decreased by 29.70% in 14 days after inoculation.But the population of actinomyces of resistant and tolerant types increased,the increasing rate showed as S.torS.sisZ.The population of fungi increased in all cultivars during the whole period.As a result,the ratios of B to F and A to F increased gradually until 14 days after inoculation,then decreased,and appeared as S.torS.sis＂Liyuanziqie＂ ＂Xi′anlvqie＂.The microorganisms,especially those in the rhizopheric soils,affected the production and transformation of root exduates,and were fed by the root exduates or some component parts.The root exudates of different resistant eggplant cultivars mainly contained Hydrocarbon,Ketone,Ester,Phenol,Phenolic acid,Aldehyde,Alcohol,Quinones and others detected by gas chromatography mass pectrometry.The category and quantity of these chemical substances were in close relation to the resistance to Verticillium wilt.It was inferenced that the resistant types contained some special components,such as Alcohol,Amide,Pyranoid,Fluorene.This may be one of the reasons for the increase of disease resistance.However,the susceptible type exhibited an opposite trend.It comprised more components,i.e.,Phenol,Ester and Phenolic acid.Many of these chemical substances were found to be allelochemical.The change of allelochemicals may be one of the reasons of resistant difference.