Developmental and Structural Section
Morawetz, Jeffery .
Haustorial structural diversity across parasitic Orobanchaceae.
Orobanchaceae present an ideal system for studying evolution of the parasitic habit in flowering plants: with a single origin of parasitism, the full range of trophic modes is represented, from non-parasites to facultative and obligate hemiparasites and holoparasites. This parasitic ability is conferred through an organ unique to parasitic plants: the haustorium. The Orobanchaceae are parasitic on the roots of their host plants through terminal and/or lateral haustoria that develop along the parasite's root system. Haustoria have a generalized internal structure, being composed of a vascular core, hyaline body, and endophyte, often with a bridge of xylem cells connecting the vasculature of host and parasite. Reports of phloem connections between host and parasite in Orobanchaceae are rare, and detailed comparative studies of haustorial structure within and across the main parasitic lineages of the family are lacking. Haustoria, representing four of five parasitic lineages within the family, were collected from plants excavated in the field, and were subsequently embedded in paraffin and plastic for structural examination. Xylem bridges were observed in all taxa examined. The proximity of parasite and host phloem, and the presence of parenchyma including transfer cells at the host-parasite interface were variable, and characteristics of these elements will be further discussed. What are the structural modifications involved in phloem-to-phloem transfer between the host and parasite in Orobanchaceae and does this include direct sieve element connections?
Log in to add this item to your schedule
1 - Rancho Santa Ana Botanic Garden, 1500 North College Ave., Claremont, CA, 91711, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Waterman Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 9:30 AM