Arabidopsis thaliana is a susceptible host plant for the holoparasite Cuscuta spec

Abstract

Arabidopsis thaliana and Cuscuta spec. represent a compatible host-parasite combination. Cuscuta produces a haustorium that penetrates the host tissue. In early stages of development the searching hyphae on the tip of the haustorial cone are connected to the host tissue by interspecific plasmodesmata. Ten days after infection, translocation of the fluorescent dyes, Texas Red (TR) and 5,6-carboxyfluorescein (CF), demonstrates the existence of a continuous connection between xylem and phloem of the host and parasite. Cuscuta becomes the dominant sink in this host-parasite system. Transgenic Arabidopsis plants expressing genes encoding the green fluorescent protein (GFP; 27 kDa) or a GFP-ubiquitin fusion (36 kDa), respectively, under the companion cell (CC)-specific AtSUC2 promoter were used to monitor the transfer of these proteins from the host sieve elements to those of Cuscuta. Although GFP is transferred unimpedly to the parasite, the GFP-ubiquitin fusion could not be detected in Cuscuta. A translocation of the GFP-ubiquitin fusion protein was found to be restricted to the phloem of the host, although a functional symplastic pathway exists between the host and parasite, as demonstrated by the transport of CF. These results indicate a peripheral size exclusion limit (SEL) between 27 and 36 kDa for the symplastic connections between host and Cuscuta sieve elements. Forty-six accessions of A. thaliana covering the entire range of its genetic diversity, as well as Arabidopsis halleri, were found to be susceptible towards Cuscuta reflexa.

Evidence for Abscisic Acid Biosynthesis in Cuscuta reflexa, a Parasitic Plant Lacking Neoxanthin

“…Symplastic connections also permit transfer of proteins, viruses (Birschwilks et al, 2006(Birschwilks et al, , 2007, and even mRNA (Roney et al, 2007) from host to parasite. ABA is transported in both phloem and xylem (Zeevaart and Boyer, 1984), so that ABA produced in the host is undoubtedly transferred to Cuscuta.…”

Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding

“…are known to take up other hostderived macromolecules, including phloem-localized GFP and mRNAs (Haupt et al, 2001;Kim et al, 2014). However, the transfer of proteins from host phloem sap probably has size limitations, since GFP (27 kD) but not GFP-ubiquitin (36 kD) can be translocated to the parasite (Birschwilks et al, 2007). It is doubtful, therefore, that myrosinase enzymes (glycosylated dimeric proteins weighing 126 to 150 kD in Arabidopsis leaves; Zhou et al, 2012) could transfer directly from the host phloem to dodder.…”

“…Dodder species utilize several brassicaceous plants as hosts in nature (Gaertner, 1950) and readily attach to Arabidopsis inflorescences (Birschwilks et al, 2007). These parasites link directly to host xylem and phloem (via penetrative organs called haustoria) and extract diverse solutes, including amino acids, sugars, hormones, proteins, mRNA, and various secondary metabolites (Rothe et al, 1999;Birschwilks et al, 2006Birschwilks et al, , 2007LeBlanc et al, 2013). It was not previously known whether dodders (or other parasitic plants) are capable of taking up host-derived glucosinolates, the major class of defense compounds produced by Arabidopsis and related plants in the order Cappareles.…”

Morphological and plant hormonal changes during parasitization by Cuscuta japonica on Momordica charantia

“…Some previous studies on parasitic plant interactions have dealt with carbon and nitrogen flows (Hibberd & Jeschke 2001), and the translocation of chemical compounds (including metabolites, small proteins, and mRNA) (Birschwilks et al 2006(Birschwilks et al , 2007LeBlanc et al 2012). While, others focused on defensive responses from host plants to parasitic plants, i.e.…”