Impact of Cuscuta australis infection on the photosynthesis of the invasive host, Mikania micrantha, under drought condition

Abstract

Cuscuta species (dodders) are widespread stem holoparasites that depend on host plants for their entire mineral and water and most carbohydrate requirements. Dodders negatively affect host photosynthesis but precise information on their impact on hosts in the presence of environmental stress factors (i.e. drought) is little known. In a pot experiment, the leaf traits, gas exchange and chlorophyll a fluorescence of the invasive climber, Mikania micrantha, parasitized by Cuscuta australis, were investigated in order to study variations of host photosynthesis in response to parasitism and drought. The results showed that the concomitant presence of C. australis infection and drought significantly impacted the leaf traits (i.e. increased leaf dry mass content), gas exchange (i.e. decreased stomatal conductance and transpiration rates and increased water-use efficiency) and quantum yield of chlorophyll a fluorescence of M. micrantha. The presence of a single stress factor (C. australis infection or drought), however, only significantly affected the leaf traits and gas exchange of M. micrantha. These results suggested that the combined additive effects of C. australis parasitism and drought significantly suppressed the photosynthesis of M. micrantha in relation to both stomatal and non-stomatal limitation of host photosynthesis. This study provides insights into Cuscuta-host interactions under drought conditions in the tropics.

High water availability increases the negative impact of a native hemiparasite on its non-native host

“…Infection had a negative effect on F v / F m of U. europaeus , regardless of water treatment. On the other hand, Le et al (2015) found that a fluorescence parameter used as a proxy for F v / F m of Mikania micrantha was negatively affected by Cuscuta australis in droughted but not in well-watered treatments. Here, infection effects may, in part, be due to the negative effect of C. pubescens on the N concentration of U. europaeus (additive infection effect; Table 5 ; Fig.…”

“…For instance, a high nitrogen supply has been found to dampen the effect of the stem holoparasite Cuscuta reflexa and the root hemiparasite Striga hermonthica on some hosts ( Cechin and Press, 1993 , 1994 ; Jeschke and Hilpert, 1997 ). While there are numerous studies on how nutrient supply affects the host–parasite relationship, there are surprisingly few studies investigating how water availability modulates the effects of the parasites on their hosts ( Evans and Borowicz, 2013 ; Le et al , 2015 ).…”

A native parasitic plant and soil microorganisms facilitate a native plant co‐occurrence with an invasive plant

“…A perturbation field experiment at two sites in England (Holme and Strumpshaw) found that R. minor structured a grassland community by selectively parasitizing components of the flora and modifying competitive interactions between plants (Gibson & Watkinson, ). Empirical studies have shown that the direction and magnitude of effects of parasitic plants may be influenced by environmental contexts like plant community composition, nutrient and moisture availability, and mycorrhizal fungi present (Le, Tennakoon, Metali, Lim, & Bolin, ; Matthies & Egli, ; Pennings & Callaway, ; Stein et al, ; Těšitel, Těšitelová, Fisher, Lepš, & Cameron, ). Because of the biotic and abiotic complexity inherent in ecological communities, the present results of a pot and mesocosm study should be corroborated by studies that are conducted under more complex ecological conditions in the field.…”

The combined effects of water and nitrogen on the relationship between a native hemiparasite and its invasive host

“…Surprisingly few papers have explored the influence of water on host : parasite associations, and most have investigated stem holoparasitic or hemiparasitic vines. For instance, although the holoparasitic vine Cuscuta australis negatively affected photosynthesis of Mikania micrantha , irrespective of water supply, its negative impact on host stomatal conductance and transpiration was enhanced in low water conditions (Le et al ., 2015). By contrast, Evans & Borowicz (2013, 2015) found that Cuscuta gronovii performed better and had a greater impact on host biomass in high water conditions.…”