title: Molecular basis of floral petaloidy: insights from androecia of Canna indica.
abstract: Floral organs that take on the characteristics of petals can occur in all whorls of the monocot order Zingiberales. In Canna indica, the most ornamental or 'petaloid' parts of the flowers are of androecial origin and are considered staminodes. However, the precise nature of these petaloid organs is yet to be determined. In order to gain a better understanding of the genetic basis of androecial identity, a molecular investigation of B- and C-class genes was carried out. Two MADS-box genes GLOBOSA (GLO) and AGAMOUS (AG) were isolated from young inflorescences of C. indica by 3' rapid amplification of cDNA ends polymerase chain reaction (3'-RACE PCR). Sequence characterization and phylogenetic analyses show that CiGLO and CiAG belong to the B- and C-class MADS-box gene family, respectively. CiAG is expressed in petaloid staminodes, the labellum, the fertile stamen and carpels. CiGLO is expressed in petals, petaloid staminodes, the labellum, the fertile stamen and carpels. Expression patterns in mature tissues of CiGLO and CiAG suggest that petaloid staminodes and the labellum are of androecial identity, in agreement with their position within the flower and with described Arabidopsis thaliana expression patterns. Although B- and C-class genes are important components of androecial determination, their expression patterns are not sufficient to explain the distinct morphology observed in staminodes and the fertile stamen in C. indica.
authors.affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China Graduate University of the Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Fu
authors.affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China.
authors.forename: Huanfang
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Plant and Microbial Biology and the University and Jepson Herbaria, University of California, Berkeley, CA 94720, USA.
authors.forename: Ana M R
authors.initials: AM
authors.lastname: Almeida
authors.affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China kuangyf05@scbg.ac.cn.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Kuang
authors.affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China.
authors.forename: Pu
authors.initials: P
authors.lastname: Zou
authors.affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China.
authors.forename: Jingping
authors.initials: J
authors.lastname: Liao
keywords: ABC model; Canna indica; MADS-box gene; floral organ identity; phylogenetic analysis; real-time PCR.