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Index >> Actinorhizal Plants (Frankia Induced Nodulation) >>Cross-inoculation Experiments

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Actinorhizal Plants Frankia Induced Nodulation Root Nodules Caused by Frankia Actinorhizal Symbiosis Cross Inoculation Experiments Isolation and Characteristics of Frankia Cultural Characteristics of Frankia Taxonomy of Frankia Entry of Frankia to the Host Plant Structure of Actinorhizal Nodule

Cross-inoculation Experiments

	Cross-Inoculation Experiments It may be recalled that cross-inoculation groups in nodulated legumes was based on the ability of rhizobia to nodulate a group of legume species. The same yardstick has been used in attempts to classify actinorhizal plants with much less success than in leguminous plants. Earlier studies were carried out by inoculating plants with nodule suspensions and with the advent of pure cultures of Frankia, similar studies have been carried out with laboratory grown cultures. The objective of cross-inoculation experiments has been to understand whether host-Frankia strain specificity exists in nature.
In general, plants from a given species were nodulated effectively by inocula prepared from crushed nodules of the same species. Exceptions were however noticed; for instance, Casuarina stricta inoculum was unable to nodulate Casuarina cristata, C. cunninghamiana and C. torulosa. Similarly, inoculum prepared from Casuarina glauca and Coriaria myrtifolia nodule suspensions did not nodulate Coriaria japonica. Likewise, Myrica pilulifera nodule homogenates did not nodulate M. gale. Other examples cited in literature have been that Alnus nodule suspensions could not nodulate Hippophae and Coriaria species but showed low level of infectivity towards Elaeagnus angustifolia and Myrica faya. Similarly, Coriaria myrtifolia inoculum was not infective on A. glutinosa, and E. angustifolia inoculum showed low infectivity on A. glutinosa.
Alnus nodule extracts did not produce nodules on Casuarina equisetifolia and similarly Casuarina nodule extracts were non-infective on Myrica and Coriaria plants. From extensive inoculation studies with pure cultures obtained from Alnus, Casuarina, Allocasuarina, Gymnostoma, Datisca, Elaeagnus, Hippophae, Shepherdia, Myrica, Comptonia, Ceanothus, Colletia, Cerocarpus, Cowania and Purshia on host plants such as Alnus gIutinosa, A. rubra, Casuarina equisetifolia, Elaeagnus angustifolia, Hippophae rhamnoides and Myrica cerifera, the following four host specificity groups were defined:
1. strains nodulating members of Alnus and Myrica 2. strains nodulating members of Casuarina and Myrica 3. strains nodulating members of Elaeagnaceae and Myrica, and 4. strains nodulating only members of Elaeagnaceae The above generatizations and many other similar reports tend to indicate that the so called cross-inoculation groups do not correlate with plant taxonomic groups and therefore may not be a sound procedure to classify Frankia isolates.

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Nitrogen Fixation and Assimilation Field Experiments on the Benefit of Frankia Inoculation Mycorrhizae and Actinorhizal Plants Proteoid Roots Genetics of Frankia Rhizobium Induced Root Nodulation of Parasponia Leaf Nodules Gymnosperm Nodules

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