Two AGAMOUS‐like MADS‐box genes from Taihangia rupestris (Rosaceae) reveal independent trajectories in the evolution of class C and class D floral homeotic functions

Abstract

Duplicate genes may be retained by sub- and/or neofunctionalization through changes in gene expression and/or coding sequence, and therefore have the potential to contribute to the genetic robustness and diversification of an organism. In this study, two MADS-box genes were isolated from Taihangia rupestris, a core eudicot species belonging to the Rosaceae. Sequence and phylogenetic analyses revealed that they are clade members of the euAG and PLE lineages, respectively, and hence the two genes are named TrAG (Taihangia rupestris AGAMOUS) and TrSHP (Taihangia rupestris SHATTERPROOF). Southern blot analysis shows that TrSHP is a single-copy gene in the T. rupestris genome. In situ hybridization analyses show that both TrAG and TrSHP are mainly expressed in the stamens, carpels, and ovules. When the stamen primordia are firstly observed, TrAG is initially expressed in the floral meristem domain that will initiate stamens and carpels. In contrast, no TrSHP signal is observed at this developmental stage. At late stages of carpel development, TrAG expression is detected in the ovules, ovaries, and developing styles and stigmas, whereas TrSHP expression is tightly restricted to the ovules. The transgenic Arabidopsis plants containing 35S::TrAG and 35S::TrSHP, respectively, showed similar phenotypes, including homeotic conversions of sepals into carpelloid structures bearing ovules and petals into staminoid organs, and the fruits shattering prematurely along the dehiscence zone. In addition, the phenotype of the transgenic 35S::TrSHP Arabidopsis plants revealed that perianth abscission was inhibited. Yeast two-hybrid assays indicated that TrAG can interact with TrSEP3, whereas TrSHP cannot. The data suggest that the euAG and PLE paralogs, TrAG and TrSHP, may have subfunctionalized and/or neofunctionalized through changes in expression patterns and accumulating variations in the coding regions. Taking these findings together with those available expression and functional data from Arabidopsis and other species, we conclude that the compensatory ways vary among the euAG and PLE lineage pairs in eudicot species.

TrMADS3, a new MADS-box gene, from a perennial species Taihangia rupestris (Rosaceae) is upregulated by cold and experiences seasonal fluctuation in expression level

“…2b). It is notable that alanine, not glycine, is present at position 111 in the K domain of TrMADS3 as in that of TrAG (Lü et al 2007). The C-terminal region of TrMADS3 shows an aspartate-and glutamate-rich stretch with little similarity to other FLC-like proteins (Fig.…”

“…The PCR fragments were labeled using Prime-a-Gene® Labeling System (Promega Madison, WI, USA). Hybridization was performed as described (Lü et al 2007). …”

Loss of deeply conserved C-class floral homeotic gene function and C- and E-class protein interaction in a double-flowered ranunculid mutant

“…There have been multiple duplication events within the C-class lineage (13) followed by partial redundancy (14)(15)(16), potential or proven subfunctionalization (17)(18)(19)(20)(21)(22)(23)(24), or switching of functional equivalence among duplicates in different species (25). Even when a single gene is present, alternative transcripts are a source of genetic variation (14).…”

Aislamiento y caracterización de genes MADS-box en Medicago truncatula: duplicaciones génicas y subfuncionalización en el linaje euAGAMOUS

“…Esta redundancia funcional ocurre inmediatamente tras la duplicación génica y se pierde cuando los genes duplicados llegan a un estado de equilibrio de redundancia parcial (Wagner, 1999). A 218 pesar de su naturaleza temporal, los genes duplicados funcionalmente redundantes existen en abundancia, ya que la redundancia protege contra las mutaciones deletéreas y contribuye a la robustez genética de un organismo (Krakauer y Nowak, 1999;Wagner, 1999;Gu, 2003;Lü et al, 2007). La redundancia funcional es frecuente en los genes ligados al desarrollo, como MtAGa y MtAGb, ya que protege contra errores en el desarrollo (Moore et al, 2005).…”

“…Cucumis sativus (Kater et al, 1998), CaMADS1 de Corylus avellana (Rigola et al, 2001), VvMADS1 de Vitis vinifera (Boss et al, 2001), TrAG y TrSHP de Taihangia rupestris (Lü et al, 2007) Estas conversiones fueron mucho más evidentes que en las plantas 2x35S::MtAGa, indicando que MtAGb probablemente tenga una implicación mayor que MtAGa en la especificación de la identidad de los órganos reproductores. Por otra parte, en las plantas 2x35S::MtAGa se observó mayor adelanto en el tiempo de floración y la generación tanto de estructuras terminales modificadas como de frutos y flores dobles, apuntando a un posible papel clave de MtAGa en la determinación del meristemo floral.…”