Different patterns of molecular, carbon and hydrogen isotope compositions of n-alkanes between heterotrophic plant and its hosts

Abstract

This study investigates the molecular, carbon, and hydrogen isotope compositions of n-alkanes in eight pairs of a holoparasitic plant (Cuscuta chinensis) and its hosts. It is unexpected that C. chinensis has a higher concentration of n-alkanes than its hosts in seven of the eight pairs, and it is preferentially dominated by n-C₂₉ alkane (representing>75% of the total n-alkanes). In addition, the d¹³C values of C₂₉ alkane in C. chinensis are less negative (avg. 1.8‰) than those in the hosts, while the d²H values of C₂₉ alkane are more negative in C. chinensis (the difference averages 48‰). We propose that the ²H-depletion of n-alkanes in the stem parasite C. chinensis may result from the utilization of stem water with less influence from evapotranspiration or the use of newly synthesized carbohydrates which is ²H-depleted relative to stored sugars. These results highlight the importance of plant nutrient status on the molecular and isotopic compositions of leaf waxes, which shed light on the (paleo)ecological potential of leaf wax d²H values.

Keywords

heterotrophic plant / Cuscuta / n-alkane / carbon isotope / hydrogen isotope

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