Ikoma, Japan—Nectaries are specialized floral tissues that secrete nectar to attract pollinators. Although the protein CRABS CLAW (CRC) is established as essential for nectary formation, the exact molecular mechanisms governing how it drives organ growth and secretion have remained unknown.
To understand the mechanism, a research team led by Professor Toshiro Ito from the Laboratory of Molecular Genetics of Floral Development, Nara Institute of Science and Technology (NAIST), Japan, worked towards identifying key genes and regulatory connections underlying nectary development and function. The team included Dr. Hideaki Iimura, Dr. Makoto Takahashi, Dr. Ryosuke Ohta, Dr. Asumi Nagamori, Dr. Seika Togawa, Dr. Yuki Furuta, Dr. Koki Nakamura, Dr. Febri Yuda Kurniawan, and Dr. Xuejing Wang; from NAIST, Japan; Dr. Nobutoshi Yamaguchi, formerly of NAIST and now at Kyoto University, Japan; Dr. Kie Kumaishi, Dr. Taiji Kawakatsu, and Dr. Yasunori Ichihashi from RIKEN BioResource Research Center, Japan; Dr. Takamasa Suzuki from Chubu University, Japan; Dr. Samantha Klasfeld and Dr. Doris Wagner from University of Pennsylvania, USA. The findings were published online in the journal of Nature Communications on October 17, 2026.
The researchers combined single-nucleus RNA sequencing with spatial transcriptomics in Arabidopsis thaliana, a widely popular model plant. Their analyses identified CRC and MYB expression in nectary-associated cell populations.
"We discovered that CRC and MYB proteins help form a DNA loop that promotes the growth of nectar-producing organs in flowers. We also found that CRC regulates genes involved in sugar transport and the synthesis of scent-related compounds," says Prof. Ito.
They also found that CRC interacts with three MYB proteins namely, MYB21, MYB24, and MYB57 and plants lacking the functions of all these proteins developed smaller nectaries, highlighting their contribution to nectary growth.
The team then focused on MAB4, a gene involved in nectary growth. They identified a regulatory DNA region downstream of MAB4 that acts as an enhancer whose disruption reduced MAB4 expression and resulted in smaller nectaries. Crucially, they detected a physical contact between the region near the MAB4 transcription start site and the downstream enhancer, a connection that was significantly reduced in the absence of functional CRC.
Based on these findings, the researchers proposed a model in which CRC and MYB proteins form a chromatin loop to activate MAB4, which regulates auxin transport to drive nectary growth.
Beyond organ development, the study revealed that CRC also regulates genes associated with sugar transport and terpene synthesis, including pathways involved in floral fragrance.
"Our study reveals connections between long-range DNA interactions, gene expression, auxin distribution, and organ growth, providing new insights and broader understanding of plant organ development," says Prof. Ito.
Future research could explore how CRC-dependent gene regulation influences the quantity and composition of nectar and the production of floral scent compounds.
