The The Cohosh Family (cimicifugeae) Petal Missing Molecular Mechanism Of A Preliminary Study

Flower is one of innovation characters of the angiosperm as the reproductive organ. The evolution of flowers is thought to underlie the extensive radiation of angiosperms through enhancement of efficient interactions with pollinators to facilitate reproductive success. Floral diversity is present through numerous variations of sepals, petals, stamens and capals that compose the typical flower. Changes in the morphology of the petal are the most diverse. The issue of petal origin has been dominated by the classic view that petals evolved independently for several times, either centripetally through the transformation of bract-like phyllomes (bracteopetals), or centrifugally from sterile stamens. The absence of a petal is wides-pread within the eudicots, even the postulated loss of petals in the caryophyllid clade.Ranunculaceae is the group of the diversity flowers. Petal is more important characters for classification in Ranunculaceae and the petal absence is observed across many clades of Ranunculaceae. Reconstruction of the presence or absence of petals suggests that the petal has been lost many times independently and perhaps regained in isolated cases. Flowers of the tribe Cimicifugeae are typical in Ranunculaceae, and absence of petals is widespread in Cimicifugeae. Kramer's results suggests that the Ranunculaceae paleoAP3 representatives form three strongly supported lineages, which we have denoted AP3-1, AP3-2, and AP3-3. The AP3-3 lineage were rarely expressed in taxa lacking petals but were always detected when petals are present. If the petals across the Ranunculales are truly independently derived, however, one might not expect to see conservation of the AP3-3/ petal correlation, and AP3-3 maybe work'open and close'in specifying petal identity. To better understand this aspect of petal identity, we conducted a comparative expression and genome structure study of 3 taxa from Cimicifugeae. We also want to know what is molecular genetics mechanism of the petal absence wihtin Ranunculaceae and how evolved the petal?Our major results are that the AP3-3 lineage were rarely expressed in taxa lacking petals but were detected when petals are present; Though comparative expression and genome structure of AP3-3 gene of Beesia calthifolia and Souliea vaginataand, we find that AP3-3 gene of Beesia calthifolia has 4 base deletion and then frameshift mutations result in loss-of function specifing petal identity changes since they drastically alter the protein sequence downstream of the frameshift site,besides creating premature stop codons; We don't find AP3-3 gene expression in Actaea asiatica. We thought that molecular genetics mechanism of the petal absence of Actaea asiatica is different from other genera of Cimicifugeae because petal morphology of Actaea asiatica looks like stamens in their development.