Project description:Innovative strategies for increasing the yield of rice, the staple food for more than half of the global population, are needed to keep pace with the expected worldwide population increase, and sustainably forefront the challenges posed by climate change. Traditionally, in Southern-East Asian countries, rice farming benefits from the use of Azolla spp., either as green manure or as co-cultivated plants, for the supply of nitrogen. Azolla spp. are ferns that, in virtue of their symbiosis with the nitrogen-fixing cyanobacterium Trichormus azollae, fix atmospheric nitrogen and release it to the environment upon decomposition of their biomass. However, if and to what extent actively growing Azolla plants impact on the development of co-cultivated rice plantlets remains to be understood. To address this point here we employed an experimental model to follow the growth and development of roots and aerial organs of rice seedlings when co-cultivated with Azolla filiculoides. We show that actively growing A. filiculoides plants alter the architecture of the roots, the transcriptome of the roots, and the hormonal profiles of both roots and leaves.