Different outcomes for the MYB floral symmetry genes DIVARICATA and RADIALIS during the evolution of derived actinomorphy in Plantago.
The gene network that specifies flower shape in Antirrhinum majus (bilateral floral symmetry or zygomorphy) includes two MYB-class genes - RADIALIS (RAD) and DIVARICATA (DIV). RAD is involved in establishing the dorsal identity program and its role is to regulate the domain of activity of DIV (the ventral identity program) by restricting it to ventral regions of the flower. Plantago is in the same family as Antirrhinum but has small, radially symmetrical (actinomorphic) flowers derived from a zygomorphic ancestral state. Here we investigate the MYB-class floral symmetry genes and the role they have played in the evolution of derived actinomorphy in Plantago lanceolata. A DIV ortholog (PlDIV) but no RAD ortholog was identified in P. lanceolata. PlDIV is expressed across all petals and stamens later in flower development, which is consistent with the loss of RAD gene function. PlDIV expression in anther sporogenous tissue also suggests that PlDIV was co-opted to regulate cell proliferation during the early stages of pollen development. These results indicate that evolution of derived actinomorphy in Plantago involved complete loss of dorsal gene function, resulting in expansion of the domain of expression of the ventral class of floral symmetry genes.
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Wesley
W
Reardon
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Pauline
P
Gallagher
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Katie M
KM
Nolan
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Hayley
H
Wright
Facultad de Biología, Universidad de Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
Maria Cruz
MC
Cardeñosa-Rubio
Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy.
Claudia
C
Bragalini
School of Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
Chui-Sang
CS
Lee
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
David A
DA
Fitzpatrick
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Killian
K
Corcoran
School of Biology, Newcastle University, Ridley Building, Newcastle, NE1 7RU, UK.
Kirsten
K
Wolff
Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Jacqueline M
JM
Nugent
D019143:Evolution, Molecular; D035264:Flowers / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D020570:Genes, myb; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics; D010943:Plantago / Q000235:genetics* / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics*
D010940:Plant Proteins; D014157:Transcription Factors
DIVARICATA; Plantago; RADIALIS; floral symmetry; pollen development