Perception of lipo-chitooligosaccharides by the bioenergy crop .

sp. is a developing feedstock for second-generation biofuel production. To ensure its success as a sustainable biofuel source, it is essential to capitalize on the ability of sp. to associate with beneficial plant-associated microbes (., mycorrhizal fungi) and engineer sp. to associate with non-native symbionts (., rhizobia). Here, we review recent research into the molecular mechanisms that control ectomycorrhizal associations in sp. with particular emphasis on the discovery that ectomycorrhizal fungi produce lipochitooligosaccharides capable of activating the common symbiosis pathway. We also present new evidence that lipo-chitooligosaccharides produced by both ectomycorrhizal fungi and various species of rhizobia that do not associate with sp. can induce nuclear calcium spiking in the roots of sp. Thus, we argue sp. already possesses the molecular machinery necessary for perceiving rhizobia, and the next step in engineering symbiosis with rhizobia should be focused on inducing bacterial accommodation and nodule organogenesis. The gene is central to these processes, and several putative orthologs are present in sp. Manipulating the promoters of these genes to match that of plants in the nitrogen-fixing clade may be sufficient to introduce nodulation in sp.