Flowers have long depended on a small organ called the nectary to offer their sweetness to visiting animals, and biologists knew that the protein CRABS CLAW was necessary for building it, yet the route by which it did so remained hidden. In a laboratory at the Nara Institute of Science and Technology in Japan, a team working with the humble model plant Arabidopsis thaliana has traced that route through a looping arrangement of DNA, in which CRABS CLAW and its partner MYB proteins draw a distant regulatory stretch into contact with a growth gene. The discovery reads as a small but telling chapt
Looping DNA Helps Flowers Build Nectar-Producing Organs, Study Finds
A DNA loop pulls a distant enhancer into contact with the gene that grows nectar
Mark
So what's the basic finding here?
Mimi
A protein called CRABS CLAW, working with MYB proteins, helps fold DNA into a loop that switches on a gene called MAB4. That gene is needed for the nectary to grow.
Mark
Why did that need explaining? Didn't we already know CRC mattered?
Mimi
We knew it was essential. We didn't know how it drove growth or secretion. This supplies a mechanism.
Luke
Worth being careful there. The loop is described as a proposed model. The team saw contact between the two DNA regions, and saw it drop without CRC, but the full picture is their interpretation.
Mark
What's the evidence that the enhancer matters?
Mimi
Disrupting that downstream region lowered MAB4 expression and gave smaller nectaries. Plants missing all three MYB proteins also had smaller nectaries.
Mark
And the scent and sugar part?
Mimi
CRC also regulates genes tied to sugar transport and terpene synthesis, which includes fragrance pathways.
Luke
But that's a regulatory link. Nobody has yet shown how it changes how much nectar a flower makes or what is in it. The source lists that as future work.
Mark
And it's all in Arabidopsis?
Luke
Yes, a model plant. Whether other flowers use the same loop isn't addressed.
Der Puls
- A protein long known to be essential for nectar organs was finally shown to work through a hidden loop in the genome.
- When the loop or its MYB partners were disrupted, the nectaries shrank, revealing how fragile the organ's growth really is.
- The team mapped gene activity in individual cells and tracked physical contact along DNA to pin down the mechanism.
- CRABS CLAW was also found to steer genes for sugar transport and fragrance chemistry, widening the story beyond size alone.
- The next step is to learn how this regulation alters nectar quantity, composition and floral scent.
Flowers have long depended on a small organ called the nectary to offer their sweetness to visiting animals, and biologists knew that the protein CRABS CLAW was necessary for building it, yet the route by which it did so remained hidden. In a laboratory at the Nara Institute of Science and Technology in Japan, a team working with the humble model plant Arabidopsis thaliana has traced that route through a looping arrangement of DNA, in which CRABS CLAW and its partner MYB proteins draw a distant regulatory stretch into contact with a growth gene. The discovery reads as a small but telling chapter in the older story of how form arises from instructions written in a genome, and how the reach of a single gene can extend across the folded architecture of a cell. What the work leaves open is how this same choreography shapes the nectar itself and the fragrances that drift from a bloom.
For years, plant scientists have known that a protein called CRABS CLAW, or CRC, is indispensable for building the nectary, the small specialized organ where a flower makes its nectar. What no one could say was how it did this. A team at the Nara Institute of Science and Technology in Japan, led by Professor Toshiro Ito, set out to find the genes and regulatory links behind nectary development, and their results have now appeared in Nature Communications.
Working in Arabidopsis thaliana, the researchers used single-nucleus RNA sequencing and spatial transcriptomics to see where CRC and MYB genes were active, and found them in the cells tied to the nectary. CRC was shown to partner with three MYB proteins, MYB21, MYB24 and MYB57. Plants lacking all three developed noticeably smaller nectaries.
The team then focused on MAB4, a gene needed for nectary growth. They identified a distant stretch of DNA that acts as an enhancer, and when it was disrupted, MAB4 expression dropped and the organs shrank. Physical contact between the gene's start region and this enhancer was markedly weaker when CRC was not working. From this they proposed that CRC and the MYB proteins together form a DNA loop, bringing the enhancer close enough to switch MAB4 on, and that MAB4 in turn guides auxin transport to drive the organ's growth.
The work also revealed that CRC regulates genes linked to sugar transport and to terpene synthesis, the pathways behind floral fragrance. Ito sees in this a broader lesson about how long-range DNA interactions, gene expression and hormone distribution work together to shape organs. The next questions turn to the nectar itself: how this regulation governs its quantity, its composition, and the scent compounds that accompany it.
A flower makes nectar in a small, specialized organ called the nectary, and for years researchers have known that one protein, CRABS CLAW, or CRC, is essential for building it. What they had not known was how. The mechanism by which CRC drives the organ's growth and its secretion was an open question until a team at the Nara Institute of Science and Technology in Japan went looking for it.
The group was led by Professor Toshiro Ito, who heads the Laboratory of Molecular Genetics of Floral Development at NAIST. Their aim was to identify the key genes and the regulatory connections behind nectary development and function. The findings were published online in Nature Communications.
The researchers worked in Arabidopsis thaliana, a widely used model plant. They combined two techniques: single-nucleus RNA sequencing, and spatial transcriptomics. Their analyses showed that CRC and MYB genes were expressed in the cell populations associated with the nectary.
Further work showed that CRC interacts with three MYB proteins: MYB21, MYB24 and MYB57. When plants lacked the functions of all three, they developed smaller nectaries, which points to a role for these proteins in the organ's growth.
The team then turned to MAB4, a gene involved in nectary growth. They found a regulatory stretch of DNA downstream of MAB4 that acts as an enhancer. When that region was disrupted, MAB4 expression fell and the nectaries came out smaller. The researchers also detected physical contact between the region near MAB4's transcription start site and the downstream enhancer. That contact was significantly reduced when CRC was not functional.
From this, they proposed a model. CRC and MYB proteins together form a chromatin loop, bringing the distant enhancer into contact with the gene and activating MAB4. MAB4 in turn regulates auxin transport, which drives the growth of the nectary. "We discovered that CRC and MYB proteins help form a DNA loop that promotes the growth of nectar-producing organs in flowers," Ito said.
The study also reached beyond organ size. CRC was found to regulate genes tied to sugar transport and to terpene synthesis, including pathways involved in floral fragrance. Ito said the work reveals connections between long-range DNA interactions, gene expression, auxin distribution and organ growth, offering broader insight into how plant organs develop.
The next questions concern the nectar itself. Future research could examine how CRC-dependent gene regulation affects the quantity and composition of nectar, and the production of floral scent compounds.
Bemerkenswerte Zitate
CRC and MYB proteins help form a DNA loop that promotes the growth of nectar-producing organs in flowers.— Professor Toshiro Ito, NAIST
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