SPL12 regulates nodulation under osmotic stress and nitrate sufficiency conditions by targeting AGL6 and AGL21 in Medicago sativa
Vida Nasrollahi, Susanne E. Kohalmi, Abdelali Hannoufa (2022) SPL12 regulates nodulation under osmotic stress and nitrate sufficiency conditions by targeting AGL6 and AGL21 in Medicago sativa. 2022 Meeting of the Canadian Association for Plant Biotechnology, Quebec City, Quebec 2022/08/22 - 2022/08/25 (oral presentation).
The highly conserved plant microRNA, miR156, affects root architecture, nodulation, nitrogen fixation, and stress response. In Medicago sativa (alfalfa) transcripts of 11 SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE, SPLs, including SPL12, are targeted for cleavage by miR156. Our previous research revealed the role of SPL12 and its target gene, AGL6, in nodulation and nitrogen fixation in alfalfa. Here we investigated the involvement of SPL12, AGL6 and AGL21 in nodulation under osmotic stress and nitrate availability conditions. Characterization of phenotypic and molecular parameters revealed that the SPL12/AGL6 module plays a negative role in maintaining nodulation under osmotic stress. There was a decrease in the nodule numbers in WT plants under osmotic stress condition, while SPL12-RNAi and AGL6-RNAi genotypes maintained nodulation. Moreover, the results showed that SPL12 regulates nodulation under nitrate treatment by silencing AGL21. AGL21 transcript levels were increased under nitrate treatment in WT plants, but SPL12 was not affected throughout the treatment period. Given that AGL21 was significantly upregulated in SPL12-RNAi plants, SPL12 may be involved in regulating nitrate inhibition of nodulation in alfalfa by targeting AGL21. Taken together, our results suggest that SPL12, AGL6 and AGL21 form a genetic module that regulates nodulation in alfalfa under osmotic stress and nitrate treatment.