Abstract Detail

Genomics / Proteomics

Morawetz, Jeffery [1], Barrett, Craig [2], Randle, Christopher [3].

Divergent photosynthetic pathway degradation in holoparasitic sister genera Harveya and Hyobanche (Orobanchaceae): Evidence from plastid genomes.

Orobanchaceae are an ideal system for studying the evolution of parasitism in plants given the family contains the full range of trophic abilities. While the majority of species are distributed in temperate regions of the world, there is a clade of tropical taxa that accounts for half of the number of genera in the family (46/92). Additionally, there is a lineage within this clade comprised of four predominantly holoparasitic genera: Aeginetia, Christisonia, Harveya and Hyobanche. Holoparasitism was thought to be plesiomorphic within this lineage, but recent phylogenetic analyses support between four and 10 independent origins of holoparasitism depending on the optimality criterion used to infer relationships. This is due to the placement of a hemiparasitic species (Harveya obtusifolia) deep within the lineage. Evidence from diverse parasitic plant lineages suggests that evolution of the holoparasitic habit is irreversible (due to rapid pseudogene formation and gene loss), thus multiple parallel origins of holoparasitism are inferred as the most likely explanation for the retention of photosynthetic ability in H. obtusifolia, rather than a single origin of holoparasitism and a re-evolution of photosynthetic capability in H. obtusifolia. Here we compare the plastome structure of two holoparasitic species: Harveya squamosa and Hyobanche atropurpurea. These species represent independent origins of the habit within this lineage, and demonstrate that not all holoparasites are created equally. In this example, morphology is not a clear indicator of degree of photosynthetic ability, pseudogene formation or plastome reduction. The implications of the presumed loss of photosynthetic ability related to holoparasite morphology will be discussed, and predictions will be made about the trends in evolution of holoparasitism within these four genera. 

1 - Rancho Santa Ana Botanic Garden, 1500 N. College Ave., Claremont, CA, 91711, USA
2 - California State University Los Angeles, Biological Sciences, 5151 State University Drive, Los Angeles, CA, 90032, USA
3 - Sam Houston State University, Department of Biological Sciences, P. O. Box 2116, Huntsville, TX, 77340, USA

Keywords:
parasitic plants
plastome
Orobanchaceae
holoparasitism
hemiparasitism
parallel evolution.

Presentation Type: Oral Paper:Papers for Topics
Session: 35
Location: Pines South/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 10:30 AM
Number: 35010
Abstract ID:99
Candidate for Awards:None