MsSPL9 Modulates Nodulation under Nitrate Sufficiency Condition in Medicago sativa.
Vida Nasrollahi1,2, Gamalat Allam1,2, Susanne E Kohalmi2
1Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON N5V 4T3, Canada.
International Journal of Molecular Sciences
|June 10, 2023
Summary
Squamosa-Promoter Binding Protein-Like 9 (SPL9) regulates alfalfa nodulation in response to nitrate. Silencing SPL9 increases nodules, while overexpression affects nitrate-responsive genes, impacting nitrogen fixation in this vital forage crop.
Area of Science:
- Plant Molecular Biology
- Legume-Rhizobia Symbiosis
- Agricultural Science
Background:
- Nodulation in legumes like alfalfa (Medicago sativa) is crucial for nitrogen fixation but breeding for nitrogen traits is underdeveloped.
- Squamosa-Promoter Binding Protein-Like 9 (SPL9), targeted by miR156, is investigated for its role in alfalfa nodulation.
Purpose of the Study:
- To investigate the function of MsSPL9 in regulating nodulation in alfalfa, particularly in response to varying nitrogen availability.
- To understand the molecular mechanisms by which MsSPL9 influences nitrate-responsive genes and nodulation.
Main Methods:
- Generated transgenic alfalfa with silenced (SPL9-RNAi) and overexpressed (35S::SPL9) MsSPL9.
- Compared nodulation phenotypes of transgenic and wild-type (WT) plants under different nitrogen conditions.
- Analyzed transcript levels of nitrate-responsive genes (NR1, NR2, NRT2.5) and the AON gene (SUNN).
Main Results:
- Silencing MsSPL9 in alfalfa significantly increased nodule formation.
- MsSPL9 regulates nodulation under high nitrate conditions by modulating NR1, NR2, NRT2.5, and SUNN gene expression.
- Overexpression of MsSPL9 increased transcript levels of these genes, while silencing led to downregulation and a nitrogen-starved phenotype.
Conclusions:
- MsSPL9 plays a key role in regulating alfalfa nodulation in response to nitrate availability.
- Understanding MsSPL9's function offers potential for improving nitrogen-use efficiency in alfalfa cultivation.
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