Abstract
The root nodule symbiosis of plants with nitrogen-fixing bacteria is phylogenetically restricted to a single clade of flowering plants, which calls for as yet unidentified trait acquisitions and genetic changes in the last common ancestor. Here we discovered-within the promoter of the transcription factor gene Nodule Inception (NIN)-a cis-regulatory element (PACE), exclusively present in members of this clade. PACE was essential for restoring infection threads in nin mutants of the legume Lotus japonicus. PACE sequence variants from root nodule symbiosis-competent species appeared functionally equivalent. Evolutionary loss or mutation of PACE is associated with loss of this symbiosis. During the early stages of nodule development, PACE dictates gene expression in a spatially restricted domain containing cortical cells carrying infection threads. Consistent with its expression domain, PACE-driven NIN expression restored the formation of cortical infection threads, also when engineered into the NIN promoter of tomato. Our data pinpoint PACE as a key evolutionary invention that connected NIN to a pre-existing symbiosis signal transduction cascade that governs the intracellular accommodation of arbuscular mycorrhiza fungi and is conserved throughout land plants. This connection enabled bacterial uptake into plant cells via intracellular support structures such as infection threads, a unique and unifying feature of this symbiosis.
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Claims 6
Claim · model-written summary
PACE was essential for restoring infection threads in nin mutants of Lotus japonicus.
- Taxon
- Lotus japonicus
Lotus japonicuse1 - Material
- nin mutantse1
- Treatment
- PACEe1
- Gene
- NINe0
- Outcome
- infection threadse1
- Direction
- restoringe1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here we discovered-within the promoter of the transcription factor gene Nodule Inception (NIN)-a cis-regulatory element (PACE), exclusively present in members of this clade”
e1“PACE was essential for restoring infection threads in nin mutants of the legume Lotus japonicus”
Claim · model-written summary
PACE sequence variants from root nodule symbiosis-competent species appeared functionally equivalent.
Verbatim
e6“PACE sequence variants from root nodule symbiosis-competent species appeared functionally equivalent”
Claim · model-written summary
Evolutionary loss or mutation of PACE is associated with loss of root nodule symbiosis in flowering plants.
- Taxon
- flowering plantsMagnoliopsidae7
- Gene
- PACEe2
- Outcome
- loss of this symbiosise2
Not reportedDirection
Verbatim
e2“Evolutionary loss or mutation of PACE is associated with loss of this symbiosis”
e7“phylogenetically restricted to a single clade of flowering plants”
Claim · model-written summary
During early nodule development, PACE dictates gene expression in a spatially restricted domain of cortical cells carrying infection threads in Lotus japonicus.
- Taxon
- Lotus japonicusLotus japonicuse1
- Organ / stage
- cortical cellse3
- Gene
- PACEe3
- Outcome
- gene expressione3
- Qualifier
- spatially restricted domaine3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“PACE was essential for restoring infection threads in nin mutants of the legume Lotus japonicus”
e3“During the early stages of nodule development, PACE dictates gene expression in a spatially restricted domain containing cortical cells carrying infection threads”
Claim · model-written summary
PACE-driven NIN expression restored the formation of cortical infection threads in tomato when engineered into the tomato NIN promoter.
- Taxon
- tomato
Solanum lycopersicume4 - Organ / stage
- corticale4
- Treatment
- PACE-driven NIN expressione4
- Gene
- NINe4
- Outcome
- formation of cortical infection threadse4
- Direction
- restorede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“PACE-driven NIN expression restored the formation of cortical infection threads, also when engineered into the NIN promoter of tomato”
Claim · model-written summary
PACE connected NIN to a pre-existing symbiosis signal transduction cascade that governs intracellular accommodation of arbuscular mycorrhiza fungi, conserved throughout land plants.
Verbatim
e5“Our data pinpoint PACE as a key evolutionary invention that connected NIN to a pre-existing symbiosis signal transduction cascade that governs the intracellular accommodation of arbuscular mycorrhiza fungi and is conserved throughout land plants”