Differential effects of ephemeral colonization by arbuscular mycorrhizal fungi in two Cuscuta species with different ecology

Abstract

Seedlings of parasitic Cuscuta species are autotrophic but can survive only a short period of time, during which they must locate and attach to a suitable host. They have an ephemeral root-like organ considered not a "true" root by most studies. In the present study, two species with contrasting ecology were examined: Cuscuta gronovii, a North American riparian species, and Cuscuta campestris, an invasive dodder that thrives in disturbed habitats. The morphology, structure, and absorptive capability of their root-like organ were compared, their potential for colonization by two species of arbuscular mycorrhizal fungi (AMF) was assessed, and the effect of the AMF on seedling growth and survival was determined. The root of both species absorbed water and interacted with AMF, but the two species exhibited dissimilar growth and survival patterns depending on the colonization level of their seedlings. The extensively colonized seedlings of C. gronovii grew more and survived longer than non-colonized seedlings. In contrast, the scarce colonization of C. campestris seedlings did not increase their growth or longevity. The differential growth responses of the AMF-colonized and non-colonized Cuscuta species suggest a mycorrhizal relationship and reflect their ecology. While C. gronovii roots have retained a higher ability to interact with AMF and are likely to take advantage of fungal communities in riparian habitats, the invasive C. campestris has largely lost this ability possibly as an adaptation to disturbed ecosystems. These results indicate that dodders have a true root, even if much reduced and ephemeral, that can interact with AMF.

Transient expression of green fluorescent protein in parasitic dodder as a tool for studying of cytoskeleton

“…For example, in C. europaea it lacks both root cap and root apical meristem ( Fig. 1B and C) as observed by other authors (Lyshede 1986;Lee et al 2000;Behdarvandi et al 2015). Several days after germination this root-like organ degrades through a senescence-like process from apex towards the stem base ( Fig.…”

“…According to some authors, stratification by cold and scarification are essential for their successful germination Furuhashi et al 2016). Variability of seed coat structure among different dodder species determines their germination characteristics impacting adaptation to natural environment (Behdarvandi et al 2015). The seeds started to germinate 2-3 days after sowing (Fig.…”

“…1E -H), possibly due to low abundance of microtubules in its cells and lack of mitotic division (Sherman et al 2008). Nevertheless, this structure is still capable of interacting with microorganisms, therefore Behdarvandi et al (2015) consider this organ to be a modification of true root. Moreover, xylem strands with non-lignified cell walls were clearly visible even under a light microscope ( Fig.…”

Aphid (Myzus persicae) feeding on the parasitic plant dodder (Cuscuta australis) activates defense responses in both the parasite and soybean host

“…200 species (Costea et al ., ), commonly known as dodders, which are worldwide distributed obligate stem parasites ranging from hemi‐ to holoparasitic (Dawson et al ., ; Braukmann et al ., ). Cuscuta seedlings do not have cotyledons and their roots are rudimentary and ephemeral, and they survive only 1–3 wk after germination without parasitizing suitable host plants (Behdarvandi et al ., ). Attached Cuscuta plants lack roots while their leaves are reduced to little scales, and their wire‐like stems coil around host shoots and form a large number of haustoria, supporting growth and parasitization (Yoshida & Shirasu, ).…”

Allopolyploid origin and genome differentiation of the parasitic speciesCuscuta veatchii(Convolvulaceae) revealed by genomic in situ hybridization

“…Cuscuta L. (Convolvulaceae; dodders) is a genus of nearly 200 species of parasitic plants with an extreme reduction or modification of vegetative structures and difficult species delimitation (Costea et al 2015). Dodders are herbaceous plants with little or no chlorophyll, filiform stems attached to the host by stem haustoria, reduced scale-like leaves, and vestigial, ephemeral roots (Stefanović et al 2007;Behdarvandi et al 2015). The genus has a nearly cosmopolitan distribution but ϳ75% are native to North and South America and belong to subgenus Grammica (Lour.)…”