Contribution of transgenic Casuarinaceae to our knowledge of the actinorhizal symbioses

Abstract

The Casuarinaceae family is a group of 96 species of trees and shrubs that are tolerant to adverse soil and climatic conditions. In the field, Casuarinaceae bears nitrogen-fixing root nodules (so called actinorhizal nodules) resulting from infection by the soil actinomycete Frankia. The association between Casuarina and Frankia is of tremendous ecological importance in tropical and subtropical areas where these trees contribute to land stabilization and soil reclamation. During differentiation of the actinorhizal nodule, a set of genes called actinorhizal nodulins is activated in the developing nodule. Understanding the molecular basis of actinorhizal nodule ontogenesis requires molecular tools such as genomics together with gene transfer technologies for functional analysis of symbiotic genes. Using the biological vectors Agrobacterium rhizogenes and A. tumefaciens, gene transfer into the two species Allocasuarina verticillata and Casuarina glauca has been successful. Transgenic Casuarinaceae plants proved to be valuable tools for exploring the molecular mechanisms resulting from the infection process of actinorhizal plants by Frankia.

Optimization of the conditions for Casuarina cunninghamiana Miq. genetic transformation mediated by Agrobacterium tumefaciens

“…Developing gene transfer techniques in casuarina trees therefore can contribute to improved tolerance to biotic and abiotic stress of these tree species. Besides, it is an important tool for the basic molecular knowledge of the symbiosis established between Frankia and casuarinas (Svistoonoff et al 2010;Zhong et al 2013).…”

Actinorhizal Signaling Molecules: Frankia Root Hair Deforming Factor Shares Properties With NIN Inducing Factor

“…In recent years, we have developed complementary bioassays using plant genes that are specifically expressed in response to interaction with a compatible Frankia . This approach is particularly well suited for C. glauca where transgenic plants containing promoters of symbiotic genes fused to either GUS or GFP can be generated ( Svistoonoff et al, 2010a ). Expressed Sequence Tag (EST) libraries of C. glauca and Alnus glutinosa ( Hocher et al, 2006 , 2011 ) provide extensive lists of genes potentially involved in the actinorhizal symbiosis.…”

Validation of candidate reference genes for qRT-PCR studies in symbiotic and non-symbiotic Casuarina glauca Sieb. ex Spreng. under salinity conditions

“…Interestingly, for several reasons C. glauca is also considered the model of actinorhizal plants (Zhong et al 2013). First, it is suitable for basic research due to the availability of a genetic transformation system (Svistoonoff et al 2010). Second, the biology of C. glauca symbiosis with Frankia and mycorrhiza has been extensively studied (Pawlowski and Demchenko 2012;He and Critchley 2008;Zhong et al 2010).…”