3 research outputs found
Floral symmetry genes elucidate the development and evolution of oil-bee pollinated flowers of Malpighiaceae and Krameriaceae
Specialization on insect and animal pollinators is thought to be the driving force for the evolution of floral traits. Specifically in the New World (NW), the oil-bee pollination syndrome has led to the convergence of floral characters in two distantly related families of core eudicots, Malpighiaceae and Krameriaceae. Both families display a flag-like structure that establishes a zygomorphic flower and floral oil rewards in epithelial elaiophores. These traits work concomitantly to attract and reward female oil-bees that help fertilize these flowers and in return receive oils. The underlying genetics of floral zygomorphy were studied in several clades of core eudicots, which implicated CYCLOIDEA2-(CYC2-)like genes of the TCP gene family to play a role in the establishment and maintenance of this trait. In Malpighiaceae, previous work demonstrated that two CYC2-like genes, CYC2A and CYC2B, are expressed during development correlated with establishing zygomorphy in flowers of NW Malpighiaceae. In this thesis work, I investigated the underlying developmental and genetic basis for the establishment of non-homologous and yet functionally similar traits in the oil-bee pollinated flowers of Malpighiaceae and Krameriaceae. In Chapter 1, I investigated the modification of a conserved CYC2 genetic program in the Old World (OW) acridocarpoids of Malpighiaceae following a major biogeographic disjunction. And in Chapter 2, I studied the floral ontogeny and genetic basis of floral zygomorphy development in Krameria lanceolata Torrey of Krameriaceae. This thesis work sheds light on the significance of the interdisciplinary study of floral symmetry evolution through comparative pollination ecology, development, and genetics
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Complex petal spot formation in the Beetle Daisy (<i>Gorteria diffusa</i>) relies on spot‐specific accumulation of malonylated anthocyanin regulated by paralogous <scp>G</scp>d<scp>MYBSG</scp>6 transcription factors
Publication status: PublishedFunder: Isaac Newton Trust; doi: http://dx.doi.org/10.13039/501100004815Funder: Cambridge Trust; doi: http://dx.doi.org/10.13039/501100003343Summary
Gorteria diffusa has elaborate petal spots that attract pollinators through sexual deception, but how G. diffusa controls spot development is largely unknown. Here, we investigate how pigmentation is regulated during spot formation.
We determined the anthocyanin composition of G. diffusa petals and combined gene expression analysis with protein interaction assays to characterise R2R3‐MYBs that likely regulate pigment production in G. diffusa petal spots.
We found that cyanidin 3‐glucoside pigments G. diffusa ray floret petals. Unlike other petal regions, spots contain a high proportion of malonylated anthocyanin. We identified three subgroup 6 R2R3‐MYB transcription factors (GdMYBSG6‐1,2,3) that likely activate the production of spot pigmentation. These genes are upregulated in developing spots and induce ectopic anthocyanin production upon heterologous expression in tobacco. Interaction assays suggest that these transcription factors regulate genes encoding three anthocyanin synthesis enzymes.
We demonstrate that the elaboration of complex spots in G. diffusa begins with the accumulation of malonylated pigments at the base of ray floret petals, positively regulated by three paralogous R2R3‐MYB transcription factors. Our results indicate that the functional diversification of these GdMYBSG6s involved changes in the spatial control of their transcription, and modification of the duration of GdMYBSG6 gene expression contributes towards floral variation within the species.
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