Abstract Detail

Comparative Genomics/Transcriptomics

Liu, Jasen [1], Ballerini, Evangeline S. [1], Hodges, Scott [2].

Evaluating the genetic basis of morphological variation in the floral nectar spurs of Aquilegia.

Understanding the processes by which diversity has been generated through evolutionary time is of major interest in the life sciences. “Key innovations” – novel phenotypic traits resulting in the diversification of taxonomic groups – offer insight into the mechanisms underlying this phenomenon. For example, floral nectar spurs have evolved independently in several angiosperm lineages and are associated with higher rates of diversification, presumably generated through coevolution with specialized mutualist pollinators. Multiple aspects of spur morphology, including width, length, and curvature can influence the efficiency of pollen transfer by different pollinator taxa. As a result, changes in these traits can result in pollinator shifts, leading to reproductive isolation and consequently, speciation. The genus Aquilegia (columbine) consists of ~70 species that rapidly evolved following the evolution of floral nectar spurs in the lineage. A useful consequence of the recent radiation in the genus is that most crosses between different species of Aquilegia produce fertile hybrids, allowing for the use of genetic mapping to understand the basis of trait divergence. Furthermore, Aquilegia exhibits extensive natural variation in spur morphology among its species, including one that has secondarily lost spurs. Previous research combining QTL mapping in F₂ hybrids between a spurred species, A. sibirica, and the spurless species, A. ecalcarata, and comparative gene expression (RNA-seq) of petals from taxa with various spur morphologies across development, identified POPOVICH (POP), a gene encoding a transcription factor that is necessary for spur development. In this study, we continue to evaluate the role of POP in the development of spurs in Aquilegia. Specifically, we examine whether or not variation in POP expression may affect additional aspects of spur morphology, such as length and curvature. Here, we measure these traits in scans of the F₂ flowers and conduct QTL mapping to identify loci contributing to their variation. Furthermore, we use qRT-PCR to characterize patterns of POP expression at different developmental stages in the petals of F₃ hybrids that vary with respect to their nectar spur length and curvature. Knowledge from this study will allow for insights into how changes in genetics and development influence speciation and morphological diversification. Furthermore, this research may allow for future comparative studies with other spurred plant taxa that have undergone similar adaptive radiations.

1 - University of California, Santa Barbara
2 - Department Of Ecology & Marine Biology, Department Of Ecology & Marine Biology, University Of California, Santa Barbara, CA, 93106, United States

Keywords:
genetics
floral evolution
floral traits
development
aquilegia.

Presentation Type: Poster
Session: P, Comparative Genomics and Transcriptomics Posters
Location: /
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PGT010
Abstract ID:426
Candidate for Awards:None