Nutritional and isotopic relationships of selected Bornean tropical mistletoe-host associations in Brunei Darussalam

Our understanding of mineral nutrition and carbon heterotrophy in mistletoes is derived largely from arid and temperate plant communities. Sharp differences between the tropical, temperate and arid communities, such as seasonality, water availability and mean temperature may influence basic assumptions regarding mistletoe physiology. Thus, we present mineral nutrition profiles and natural abundance carbon and nitrogen stable isotope data for tropical mistletoes and their hosts. Parasite-host mineral nutrition profiles were estimated for three Loranthaceous mistletoes: Scurrula ferruginea Danser, Macrosolen cochinchinensis Blume, and Dendrophthoe curvata Blume and 12 unique mistletoe-host associations. delta C-13 and delta N-15 values were estimated for 12 parasite-host associations. Differences between host and parasite delta C-13 values were small but showed significant depletion in mistletoe leaves compared with the distal branch and proximal branch host leaves. Host and mistletoe delta C-13 values were uncorrelated whereas delta N-15 values were significantly correlated, demonstrating mistletoe N dependence. Concentrations of K were higher in mistletoes relative to hosts and significantly higher for Dendrophthoe host associations. For Scurrula and Macrosolen, mean mistletoe-host concentrations of major and minor elements did not differ significantly.