Highly active nodule gene turns out to be dispensable
Biró JB, Domonkos Á, Güngör B, Farkas A, Mohammadi Eghbash E
Crispr
The nitrogen-fixing nodules on your beans' and peas' roots run on hundreds of specialized genes, and figuring out which ones actually matter helps breeders eventually engineer more efficient, fertilizer-saving legume crops for the garden and the farm.
Legume plants like alfalfa form little bumps on their roots called nodules, where friendly bacteria convert air nitrogen into plant food. A gene named NOD25 is switched on at huge levels inside these nodules, so researchers assumed it must be essential and used gene-editing tools to delete it in a lab relative of alfalfa. The edited plants formed normal nodules and fixed nitrogen just fine, meaning this particular gene is a bystander rather than a key player, at least under the conditions tested.
Key Findings
CRISPR/Cas9 was used to create four independent Mtnod25 loss-of-function mutant lines in Medicago truncatula
All four mutant lines showed normal growth and no defects in nodule colonization, symbiosome formation, or bacteroid differentiation
MtNOD25-like proteins have a repetitive modular structure conserved across IRLC legumes, suggesting a specialized but non-essential role
chevron_right Technical Summary
Scientists disabled a gene called NOD25 that's extremely active in the root nodules where legumes house nitrogen-fixing bacteria, expecting it to be important. Surprisingly, plants without the gene grew and formed symbiotic nodules completely normally, showing this particular gene isn't required for the partnership after all.
Abstract Preview
Original paper
Loss of Nod25 function does not affect nitrogen-fixing symbiosis in Medicago truncatula.
The formation of nitrogen-fixing symbiotic nodules is a complex process that involves extensive transcriptional reprogramming of legume roots to enable intracellular accommodation of host compatibl...
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Alfalfa, lucerne, Medicago sativa is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world and is used for grazing, hay, and silage, as well as a green manure and cover crop. It has also been cultivated as livest...