Assessing Frankia populations in plants and soil using molecular methods
Assessing Frankia populations in plants and soil using molecular methods
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DOI：
10.1111/j.1574-6941.1999.tb00613.x
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发表时间：
1999-07
影响因子：
4.2
通讯作者：
D. Hahn;Anja Nickel;J. Dawson
中科院分区：
文献类型：
--
作者：
D. Hahn;Anja Nickel;J. Dawson
近年来，分子生物学方法越来越多地补充了结节依赖的检测方法研究自然界中的Frankia种群。这些新方法揭示了Frankia的遗传多样性和分布，并完善和扩展了有关内生菌-宿主特异性的知识。基于PCR的方法已被用来解开菌株的系统发育关系，以及未培养的内生菌在根瘤中的许多放线菌植物，没有菌株已获得。PCR扩增的16 S核糖体DNA的比较序列分析导致Frankiaceae的修正，仅包含Frankia属，具有四个主要亚部：（i）主要包含Frankia alni和分别属于Alnus和木麻黄宿主感染群的其它典型固氮菌株的大群，（ii）Dryas、Coriaria和Datisca物种的未培养的内生菌，（iii）胡颓子属宿主感染组的菌株和（iv）非典型非固氮菌株。利用PCR扩增的16 S rRNA基因片段、谷氨酰胺合成酶II（glnII）基因片段、16 S-23 S rRNA操纵子的基因间间隔片段或固氮酶nifH和nifD（nifH-D）或nifD和nifK（nifD-K）基因之间的基因间间隔片段的RFLP分析表明，培养的Frankia菌株和未培养的根瘤内生菌之间存在相当大的多样性。越来越多的数据库的歧视性目标序列Frankiae越来越多地利用特定Frankia种群的分布在环境中使用PCR或原位杂交的研究。直到最近，大多数研究都集中在根瘤中Frankia种群的分析，根瘤是这种生物富集的自然场所。然而，这些人口，仅代表部分的生理活性，感染Frankiae在土壤中，而不是总Frankia人口。因此，未来的方法，Frankia种群的研究，应纳入许多机会，不仅仅是系统发育分析，多样性的描述和研究Frankia种群的结节。分子方法打开了大门，更复杂的研究环境的影响，土著或引进的Frankia种群在植物和土壤中的动态。这些研究可能会导致进步的放线菌植物和Frankia的管理，提供特定的Frankia种群可以归因于林业有益的功能。这些特征包括在土壤中的持久性和生长，与效率较低的Frankia种群竞争结瘤，迅速和有效的结瘤形成以及最终的上级固氮能力。
In recent years, molecular approaches have increasingly supplemented nodulation-dependent detection methods for studying Frankia populations in nature. The new methods are revealing much about the genetic diversity and distribution of Frankia, as well as refining and expanding knowledge about endophyte-host specificities. PCR-based approaches have been used to unravel the phylogenetic relationships of isolates, as well as of uncultured endophytes in root nodules of many actinorhizal plants from which no isolates have been obtained. A comparative sequence analysis of PCR-amplified 16S ribosomal DNA led to the emendation of the family Frankiaceae to contain only the genus Frankia with four main subdivisions: (i) a large group mainly comprising Frankia alni and other typical nitrogen-fixing strains belonging to the Alnus and the Casuarina host infection groups, respectively, (ii) uncultured endophytes of Dryas, Coriaria and Datisca species, (iii) strains of the Elaeagnus host infection group and (iv) atypical non-nitrogen-fixing strains. A considerable diversity among both cultured Frankia strains and uncultured endophytes in nodules was indicated using RFLP analyses of PCR-amplified fragments of the 16S rRNA gene, the glutamine synthetase II (glnII) gene, the intergenic spacer of the 16S-23S rRNA operon or the intergenic spacer between the nitrogenase nifH and nifD (nifH-D) or the nifD and nifK (nifD-K) genes. The growing database of discriminative target sequences for frankiae is increasingly exploited for studies on the distribution of specific Frankia populations in the environment using PCR or in situ hybridization. Until recently, most studies have focused on the analysis of Frankia populations in root nodules, the natural locale of enrichment for this organism. These populations, however, represent only the fraction of physiologically active, infecting frankiae in soils rather than the total Frankia population. Future approaches to studies of Frankia populations should therefore incorporate the many opportunities for more than just phylogenetic analyses, the description of diversity and studies of Frankia populations in nodules. The molecular approaches open the door to more sophisticated studies of environmental influences on the dynamics of indigenous or introduced Frankia populations in plants and soil. These studies may lead to advancements in the management of actinorhizal plants and Frankia, provided specific Frankia populations can be attributed with silviculturally beneficial features. Such features include persistence and the growth in soil, competition with less efficient Frankia populations for nodule formation, prompt and efficient nodule formation and an ultimately superior nitrogen-fixing capacity.