Jinshun Zhong1, Elizabeth A Kellogg1. 1. Department of Biology, The University of Missouri - St. Louis, One University Boulevard, St. Louis, Missouri 63121 USA.
Abstract
UNLABELLED: • PREMISE OF THE STUDY: CYCLOIDEA2 (CYC2)-like and RADIALIS (RAD)-like genes are needed for the normal development of corolla bilateral symmetry in Antirrhinum majus L. (snapdragon, Plantaginaceae, Lamiales). However, if and how changes in expression of CYC2-like and RAD-like genes correlate with the origin of corolla bilateral symmetry early in Lamiales remains largely unknown. The asymmetrical expression of CYC2-like and/or RAD-like genes during floral meristem development could be ancestral or derived in Plantaginaceae.• METHODS: We used in situ RNA localization to examine the expression of CYC2-like and RAD-like genes in two early-diverging Lamiales.• KEY RESULTS: CYC2-like and RAD-like genes are expressed broadly in the floral meristems in early-diverging Lamiales with radially symmetrical corollas, in contrast to their restricted expression in adaxial/lateral regions in core Lamiales. The expression pattern of CYC2-like genes has evolved in stepwise fashion, in that CYC2-like genes are likely expressed briefly in the floral meristem during flower development in sampled Oleaceae; prolonged expression of CYC2-like genes in petals originated in the common ancestor of Tetrachondraceae and core Lamiales, and asymmetrical expression in adaxial/lateral petals appeared later, in the common ancestor of the core Lamiales. Likewise, expression of RAD-like genes in petals appeared in early-diverging Lamiales or earlier; asymmetrical expression in adaxial/lateral petals then appeared in core Lamiales.• CONCLUSIONS: These data plus published reports of CYC2-like and RAD-like genes show that asymmetrical expression of these two genes is likely derived and correlates with the origins of corolla bilateral symmetry.
UNLABELLED: • PREMISE OF THE STUDY: CYCLOIDEA2 (CYC2)-like and RADIALIS (RAD)-like genes are needed for the normal development of corolla bilateral symmetry in Antirrhinum majus L. (snapdragon, Plantaginaceae, Lamiales). However, if and how changes in expression of CYC2-like and RAD-like genes correlate with the origin of corolla bilateral symmetry early in Lamiales remains largely unknown. The asymmetrical expression of CYC2-like and/or RAD-like genes during floral meristem development could be ancestral or derived in Plantaginaceae.• METHODS: We used in situ RNA localization to examine the expression of CYC2-like and RAD-like genes in two early-diverging Lamiales.• KEY RESULTS: CYC2-like and RAD-like genes are expressed broadly in the floral meristems in early-diverging Lamiales with radially symmetrical corollas, in contrast to their restricted expression in adaxial/lateral regions in core Lamiales. The expression pattern of CYC2-like genes has evolved in stepwise fashion, in that CYC2-like genes are likely expressed briefly in the floral meristem during flower development in sampled Oleaceae; prolonged expression of CYC2-like genes in petals originated in the common ancestor of Tetrachondraceae and core Lamiales, and asymmetrical expression in adaxial/lateral petals appeared later, in the common ancestor of the core Lamiales. Likewise, expression of RAD-like genes in petals appeared in early-diverging Lamiales or earlier; asymmetrical expression in adaxial/lateral petals then appeared in core Lamiales.• CONCLUSIONS: These data plus published reports of CYC2-like and RAD-like genes show that asymmetrical expression of these two genes is likely derived and correlates with the origins of corolla bilateral symmetry.
Authors: Hélène L Citerne; Elisabeth Reyes; Martine Le Guilloux; Etienne Delannoy; Franck Simonnet; Hervé Sauquet; Peter H Weston; Sophie Nadot; Catherine Damerval Journal: Ann Bot Date: 2016-12-26 Impact factor: 4.357