Floral Volatiles in Parasitic Plants of the Orobanchaceae. Ecological and Taxonomic Implications

Abstract

The holoparasitic broomrapes, Orobanche spp. and Phelipanche spp. (Orobanchaceae), are root parasites that completely depend on a host plant for survival and reproduction. There is considerable controversy on the taxonomy of this biologically and agronomically important family. Flowers of over 25 parasitic Orobanchaceae and a number of close, parasitic and non-parasitic, relatives emitted a complex blend of volatile organic compounds (VOCs), consisting of over 130 VOCs per species. Floral VOC blend-based phylogeny supported the known taxonomy in internal taxonomic grouping of genus and eliminated the uncertainty in some taxonomical groups. Moreover, phylogenetic analysis suggested separation of the broomrapes into two main groups parasitizing annual and perennial hosts, and for the annual hosts, into weedy and non-weedy broomrapes. We conclude that floral VOCs are a significant tool in species identification and possibly even in defining new species and can help to improve controversial taxonomy in the Orobanchaceae.

Revisiting weed infestation of agricultural lands from zones near utility poles

“…In accordance with agrobiological classification [7], annual and perennial nonparasitic weeds were found around utility poles [8]. Annual weeds are characterized by seed reproduction, life cycle of no more than 2 years, and die right after seeds develop.…”

A Survey of the Floral Volatile Profiles of Daylily Species and Hybrids

“…HCA based on volatile content has been used to explore taxonomic relatedness in other plant systems, including citrus [Citrus sp. (Jing et al, 2015;Zhang et al, 2017)], parasitic plants [Orobanchaceae (Toth et al, 2016)], blueberries [Vaccinium sp. (Gilbert et al, 2015)], and Cymbopogon grasses (Khanuja et al, 2005); however, the results of clustering based solely on volatile profiles do not always coincide with established taxonomy.…”

Taxonomic traits in the microstructure of flowers of parasitic Orobanche picridis with particular emphasis on secretory structures

“…Researchers agree that Orobanche spp. differ in the presence of metabolites in trichome cells: El-Akkad et al (2002) and Hassan and El-Awadi (2009) detected the presence of lipid, lignin, phenolic, and suberin materials, Sacchetti et al (2003) described the content of terpenes and flavonoids, Hegnauer (1990) identified iridoid glycosides and sesquiterpenes, Serafini et al (1995) demonstrated the presence of phenylpropanoid glycosides, and Tóth et al (2016) detected floral volatile organic compounds. The authors of the present study believe that the presence of alkaloids as well as tannins and flavonoids in the O. picridis trichomes provides protection to these plants against herbivore foraging and fungal or bacterial diseases.…”

“…Bumblebees, Colletid and Halictid bees, wasps, and stiletto flies visit Orobanche flowers from early morning to late afternoon (Jones 1991;Toth et al 2013). The flowers attract insects with their fragrance (Hegnauer 1990;Piwowarczyk et al 2015;Tóth et al 2016) and offer pollen and nectar reward (Saghir and Dastgheib 1978;Ollerton et al 2007). Annular nectaries in Orobanche flowers are located at the base of the ovary (Kreutz 1995;Bekker and Kwak 2005;Fahmy 2013).…”