Genetic basis and dual adaptive role of floral pigmentation in sunflowers

eLife

Jean-Sébastien Légaré¹  Marco Todesco¹  Mojtaba Jahani¹  Amy Kim¹  Natalia Bercovich¹  Ivana Imerovski¹  Loren H Rieseberg¹  Óscar Dorado Ruiz¹  Gregory L Owens²  Srinidhi V Holalu³  Benjamin K Blackman³  Lufiani L Madilao⁴ 

[1] Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada;Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada;Department of Biology, University of Victoria, Victoria, Canada;Department of Plant and Microbial Biology, University of California, Berkeley, United States;Michael Smith Laboratory and Wine Research Centre, University of British Columbia, Vancouver, United States;

关键词: sunflower;    floral pigmentation;    pollination;    abiotic stress;    adaptation;    transcription factors;    Other;    Sunflower (Helianthus annuus);   

DOI  :  10.7554/eLife.72072

来源: eLife Sciences Publications, Ltd

【 摘 要 】

Variation in floral displays, both between and within species, has been long known to be shaped by the mutualistic interactions that plants establish with their pollinators. However, increasing evidence suggests that abiotic selection pressures influence floral diversity as well. Here, we analyse the genetic and environmental factors that underlie patterns of floral pigmentation in wild sunflowers. While sunflower inflorescences appear invariably yellow to the human eye, they display extreme diversity for patterns of ultraviolet pigmentation, which are visible to most pollinators. We show that this diversity is largely controlled by cis-regulatory variation affecting a single MYB transcription factor, HaMYB111, through accumulation of ultraviolet (UV)-absorbing flavonol glycosides in ligules (the ‘petals’ of sunflower inflorescences). Different patterns of ultraviolet pigments in flowers are strongly correlated with pollinator preferences. Furthermore, variation for floral ultraviolet patterns is associated with environmental variables, especially relative humidity, across populations of wild sunflowers. Ligules with larger ultraviolet patterns, which are found in drier environments, show increased resistance to desiccation, suggesting a role in reducing water loss. The dual role of floral UV patterns in pollinator attraction and abiotic response reveals the complex adaptive balance underlying the evolution of floral traits.

【 授权许可】

CC BY