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

• Published in: Weed biology and management 2015-12, Vol.15 (4), p.138-146
• Main Authors: Le, Quang-Vuong, Tennakoon, Kushan U., Metali, Faizah, Lim, Linda B.L., Bolin, Jay F.
• Format: Article
• Language: English
• Subjects: chlorophyll a fluorescence transient test; Cuscuta; gas diffusional limitations; light-use efficiency; Mikania micrantha; parasite-host interactions
• ISSN: 1444-6162; 1445-6664
• DOI: 10.1111/wbm.12077

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.