BACKGROUND Bilateral symmetry flower (zygomorphy) is the ancestral state for Gesneriaceae species. Yet independent reversions to actinomorphy have been parallelly evolved in several lineages. Conandron ramondioides is a natural radially symmetrical species survived in dense shade mountainous habitats where specialist pollinators are scarce. Whether the mutations in floral symmetry genes such as CYC, RAD and DIV genes, or their expression pattern shifts contribute to the reversion to actinomorphy in C. ramondioides thus facilitating shifts to generalist pollinators remain to be investigated. To address this, we isolated putative orthologues of these genes and relate their expressions to developmental stages of flower actinomorphy. RESULTS Tissue specific RT-PCR found no dorsal identity genes CrCYCs and CrRADs expression in petal and stamen whorls, while the ventral identity gene CrDIV was expressed in all petals. Thus, ventralized actinomorphy is evolved in C. ramondioides. However, CrCYCs still persists their expression in sepal whorl. This is congruent with previous findings that CYC expression in sepals is an ancestral state common to both actinomorphic and zygomorphic core Eudicot species. CONCLUSIONS The loss of dorsal identity genes CrCYCs and CrRADs expression in petal and stamen whorl without mutating these genes specifies that a novel regulation change, possibly on cis-elements of these genes, has evolved to switch zygomorphy to actinomorphy.

中文翻译：

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花对称基因的表达变化与东亚地方病Conandron ramondioides（Gesneriaceae）中的花光化性相关。

背景技术双边对称花（合子）是Gesneriaceae物种的祖先状态。然而，在多个谱系中已经并行地进化出独立的向光化形态的回复。Conandron ramondioides是一种自然的径向对称物种，可以在没有专业传粉媒介的茂密阴暗山区栖息地中生存。花对称基因（例如CYC，RAD和DIV基因）中的突变，或它们的表达模式变化是否有助于雷蒙角梭菌恢复到光化性，从而促进向多花传粉者的转化。为了解决这个问题，我们分离了这些基因的假定直向同源物，并将它们的表达与花光化形态的发育阶段联系起来。结果组织特异性RT-PCR未发现在花瓣和雄蕊螺纹中有背侧同一性基因CrCYCs和CrRADs表达，腹侧同一性基因CrDIV在所有花瓣中表达。因此，腹腔放线的形态发生在C. ramondioides。但是，CrCYCs仍然在萼片螺纹中表达。这与以前的发现一致，即萼片中的CYC表达是放线型和合型核心Eudicot物种共有的祖先状态。结论花瓣和雄蕊轮中背侧同一性基因CrCYCs和CrRADs表达的缺失而没有使这些基因突变，这表明可能在这些基因的顺式元件上发生了新的调控变化，从而将合子形态转换为光化形态。这与先前的发现一致，即萼片中的CYC表达是放线型和合型核心Eudicot物种共有的祖先状态。结论花瓣和雄蕊轮中背侧同一性基因CrCYCs和CrRADs表达的缺失而没有使这些基因突变，这表明可能在这些基因的顺式元件上发生了新的调控变化，从而将合子形态转换为光化形态。这与以前的发现一致，即萼片中的CYC表达是放线型和合型核心Eudicot物种共有的祖先状态。结论花瓣和雄蕊轮中背侧同一性基因CrCYCs和CrRADs表达的缺失而没有使这些基因突变，这表明可能在这些基因的顺式元件上发生了新的调控变化，从而将合子形态转换为光化形态。