植物叶片内生放线菌的分离、分类与拮抗活性

以四川采集的芍药和北京采集的三叶草的叶片为材料,经表面消毒程序后,分离出内生放线菌15株。通过表观特征比较和BOX-PCR基因指纹图谱分析的方法,将分离出的放线菌归并于12个不同的基因型,其中6个来自芍药,6个来自三叶草。结合16S rRNA基因序列分析可知,分离菌株除C4、C5属于假诺卡氏菌外,其余的13株都是链霉菌;菌株C12与最近模式种的16S rRNA基因序列相似性较低,为96.6%。对分离菌株的抗菌活性实验表明,有11株在一个或一个以上的测试中呈阳性;其中6株对植物致病菌立枯丝核菌有明显抗性,占阳性菌株的55%。

Isolation, classification and antimicrobial activity of endophytic actinomycetes from plant leaves

Leave samples of Paeonia lactiflora and Trifalium repens were collected from Sichuan Province and Beijing respectively to study their endophytic actinmycetes. After a well-established surface-sterilized procedure, the samples were plated on agar media of TWYE, HV, YECD, NA and WA, followed by incubation at 28 degrees C for 2 - 4 weeks. With the help of light microscope, 15 actinomycetes strains were isolated from the plates. Comparison of cultural features and fingerprinting analyses of BOX-PCR products were performed to cluster the isolates, with the result that all the strains were assigned to 12 different genotypes, half of them from Paeonia lactiflora and half from Trifalium repens. A combination of morphological and 16S rRNA gene sequence data showed that except strains C4 and C5, which belonged to Pseudonocardia, 13 of the isolates were streptomycetes. Most isolates share high 16S rRNA gene sequence similarities to known type strains. However, strain C12 shares low values, 96.6% in maximum, and strain C5 shares 97.9% in maximum; more assays are needed to ascertain their taxonomic positions. In the tests of antimicrobial activity against 7 bacteria, 3 fungi and 1 yeast, 11 isolates were positive in one or more tests, and 55% of the positive ones could inhibit the growth of Rhizoctonia solani, a significant pathogen of plants.