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Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Min, Ya [1], Bunn, J. Imani [2], Kramer, Elena [3].

Sweet genes are made of STYLISH – Members of the STYLISH gene family control both style and nectary development in Ranunculids.

The presence of floral nectaries is a particularly interesting example of convergent traits in flowering plants, and is considered to be associated with the adaptation and diversification of numerous angiosperm lineages. For instance, the petal spurs of Aquilegia flowers is regarded as a key innovation, but the adaptive radiation of the New World Aquilegia species would have been unlikely to have occurred if there were no nectaries at the distal tips of the petal spurs to reward pollinators. To date, however, we have very little knowledge of what genes contribute to nectary development and evolution, particularly in non-core eudicot taxa. In the current study, we investigated the functions of genes from the STYLISH (STY) family in A. coerulea, because all the STY members, AqSTY1, AqSTY2, and AqLRP, were shown to be enriched in young petal cups in a previous RNA-sequencing work, with AqSTY1 showed the strongest differential expression between petal cups and blades among all candidate genes. In situ hybridization revealed that during the stages when the nascent petal spurs start to emerge, AqSTY1 exhibits concentrated expression in the presumptive nectary site in the inner surface of the growing spur tip, AqSTY2 showed diffused expression in the growing spur. Single and triple gene knock down revealed that these three genes function redundantly in style and nectary development, and triple silencing led to absence of nectary. Since members of the STY family are known to redundantly control auxin homeosis in land plants, this functional conservation may explain the defects in stigmatic tissue in Aquilegia flower. However, no previous study among the core eudicot has reported STY genes function in nectary development, suggesting the genes have been co-opted to this role in Aquilegia. Moreover, strong expression of STY homologs in nectary-bearing petals has also been detected in Delphinium and Epimedium, suggesting that this co-option event is likely to have occurred before the diversification of the family Ranunculaceae and Berberidaceae. Since the identification of the first gene controlling nectary development in 1999, the STY homologs of the Ranunculaceae are the only alternative loci for the control of nectary development in flowering plants, providing a critical data point in understanding the evolutionary origin and developmental basis of nectaries.

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1 - Kramer Lab Biolabs Room 1119, 16 Divinity Ave., Cambridge, MA, 02138, United States
2 - Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Biolabs Room 1119, Cambridge, MA, 02138, United States
3 - Harvard Univ., OEB, 16 Divinity Avenue, Cambridge, MA, 02138, United States

style development
nectary development

Presentation Type: Oral Paper
Session: 20, Evolutionary Developmental Biology (Evo-Devo) I
Location: 113/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 8:30 AM
Number: 20003
Abstract ID:177
Candidate for Awards:Katherine Esau Award

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