What is it about?
Most flowers have multiple petals. In some, petals are separate; in others, they join at the base or even fuse completely into a tube—a trait called sympetaly. The Asteraceae family is one of the most diverse plant groups, commonly found in roadsides and lawns. What we call a single "chrysanthemum flower" is actually a head made of many florets, each formed by five fused petals. For a long time, scientists did not understand how chrysanthemum florets achieve petal fusion from their earliest stages, or why they show such a wide range of fusion degrees and shapes. Our research found that auxin, a common plant hormone, acts like a conductor. It directs a series of genes to precisely control the growth of two of the five petals. This simple control creates the diverse forms of chrysanthemum florets with different levels of petal fusion.
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Why is it important?
This study solves a long-standing puzzle in plant evolution: how early-sympetalous flowers develop corolla tubes with varying degrees of fusion. Sympetaly is a key evolutionary innovation that helps flowers attract pollinators and achieve efficient reproduction, and it also forms the main ornamental structure of many flowering plants. Uncovering this developmental mechanism helps us understand why flowers in nature show such rich morphological diversity. Furthermore, our results offer new directions for chrysanthemum breeding, allowing us to design varieties with flatter petals or more tubular florets to increase their value as cut flowers and garden plants.
Perspectives
For me, the most meaningful part of this work is that we chose the humble chrysanthemum—so common in daily life, yet one of the world’s most beloved cut flowers—to tackle a classic, long-unanswered question in plant evolution: how petal fusion came to be. For years, people thought sympetaly was an "all-or-nothing" trait. But we found it is controlled by an incredibly delicate regulatory system. By tuning the growth of just two dorsal petals via auxin signaling, the plant can create a whole spectrum of flower forms, from barely fused to fully tubular. What truly moved me is realizing that even these everyday flowers hold such complex, elegant developmental blueprints. This study reminds me that there is hidden precision in every ordinary natural thing, waiting for us to uncover. To be part of this kind of exploration—peeling back the layers of how nature works—has been one of the most satisfying experiences of my research career.
Jia Diwen
Nanjing Agricultural University
Read the Original
This page is a summary of: An auxin-induced transcriptional cascade CmBES1–CmSAUR66 orchestrates the ray floret development in
Chrysanthemum morifolium, Proceedings of the National Academy of Sciences, April 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2527961123.
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