Detection of Arbuscular Mycorrhizal Fungi in the Roots of Strawberry with Nested PCR Technique

Organic farming of strawberry fruit crops is being increasingly developed in Poland. There is no possibility of using mineral fertilizers and chemical plant protection products in such a system of cultivation. The Rhizosphere Laboratory of the Research Institute of Horticulture in the Skierniewice has been working on the development and practical implementation of bioproducts enriched with beneficial soil microorganisms that have a positive effect on the growth and development of strawberry plants.

An analysis of the impact of bioproducts on plants requires an assessment of the colonization of the plant roots by beneficial, arbuscular mycorrhizal fungi (AMF). Because of the difficulty in detecting and identifying AM fungi, the mycelium of which cannot be maintained outside the host plant, use is made of molecular biology techniques based on DNA analyses of these fungi.

The aim of this study was to use a nested PCR technique to establish the presence of arbuscular mycorrhizal fungi in the roots of strawberry plants treated with bioproducts.

The tests were performed on the DNA obtained from the roots of strawberry plants of the cultivars Elsanta and Honeoye treated with bioproducts of natural origin. In terms of fertilization, the control combinations were made up of plants that were not fertilized (control 0) and plants fertilized with NPK (control NPK). In the molecular tests, the control was the DNA obtained from the leaves of strawberry plants of the two cultivars. Colonization of strawberry roots by mycorrhizal fungi was determined on the basis of the presence of PCR products of a specific size, which were characteristic of the genera of the tested fungi. Primers amplifying the region of the large subunit ribosomal gene (LSU rDNA), which were specific to the genera Glomus, Acaulospora and Scutellospora, were used.

As a result of the tests, DNA fragments were obtained that confirmed the presence of mycorrhizal fungi in all the samples of roots with the exception of those that came from the control combination of cultivar Honeoye fertilized with NPK. The roots of the plants were found to contain DNA fragments characteristic of three clusters of the genus Glomus. The presence of fungi Acaulospora was detected in all the samples of cultivar Honeoye roots except the roots of the control plants fertilized with NPK. Reaction products characteristic of the Acaulospora fungi in the roots of cultivar Elsanta were observed in the samples taken from the plants treated with bioproducts, with the exception of the control plants and plants fertilized with manure. Moreover, the test samples of both cultivars were found to contain fungi belonging to two clusters of the genus Scutellospora.

The tests made it possible to detect the presence of arbuscular mycorrhizal fungi in the roots of strawberry plants. In addition, the analyses have shown the usefulness of most of the primers used for detecting the presence of mycorrhizal fungi of the genera Glomus, Acaulospora and Scutellospora. The results will be used to assess the effects of bioproducts on the growth and yield of strawberry plants of the cultivars Elsanta and Honeoye, and on the colonization of the roots of these plants by AM fungi.