Characterization of SPL12 role in regulating root architecture, nodulation and nitrogen fixation in Medicago sativa
Nasrollahi V, Kohalmi SE, Hannoufa A (2021) Characterization of SPL12 role in regulating root architecture, nodulation and nitrogen fixation in Medicago sativa. The Eastern Regional Meeting of the Canadian Society of Plant Biologists. Carleton University, Nov 27 (virtual)
The root system architecture in plants is critical because of its role in controlling nutrient cycling, water use efficiency and resistance to biotic and abiotic stresses. Similar to most other phenotypic traits, root system architecture is controlled at the molecular level by many genes, some of which were recently identified, including some coding for transcription factors from the SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family. We previously showed that transgenic Medicago sativa (alfalfa) plants overexpressing microRNA156 (miR156) show increased nodulation, nitrogen fixation and longer roots. At least sixteen SPL genes including SPL12 are targeted for silencing by microRNA156 in alfalfa. Thus, association of each target SPL gene to a trait or set of traits is essential for developing molecular markers for alfalfa breeding.
To determine the role of SPL12 gene in root architecture and nodulation by investigating the phenotypic changes associated with altered expression of SPL12 and by determining SPL12 targets. In this study, we used three SPL12 silenced and overexpression alfalfa plants to investigate the role of SPL12. Furthermore, we conducted transcriptomics analysis of SPL12 RNAi alfalfa roots and identified differentially expressed genes. Phenotypic analysis showed that alfalfa plants with reduced SPL12 level had an increase in nodulation and root regeneration. Illumina next-generation sequencing-based transcriptomics in root tissues of SPL12 silenced genotypes also revealed SPL12 effects on genes involved in nodulation and nitrogen assimilation pathways. The present findings suggest that SPL12 regulates root development and nodulation, as well as in nitrogen uptake and assimilation pathways.