Influence of halophytic hosts on their parasites – the case of Plicosepalus acaciae
Halophytes develop various morphological and physiological traits that enable them to grow successfully on saline substrates. Parasitic plants on halophytic hosts may also encounter salt stress. We investigated the mistletoe Plicosepalus acaciae (syn: Loranthus acacia; Loranthaceae), which occurs on five halophytic and at least ten non-halophytic hosts in the Southern Arava-Valley (Israel). P. acaciae is a common parasite north of Eilat to the Dead Sea area and in the Jordan Valley. Morphological and physiological responses of P. acaciae to salinity were investigated by comparison of plants on halophytic with those on non-halophytic hosts. Ion patterns of different host-parasite associations were determined as was the development of leaf succulence at different growth stages. The leaf water content of P. acaciae increased and leaves developed succulence when growing on halophytic hosts, especially on Tamarix species, where leaf water content was 3 times higher than on non-halophytic hosts and the leaf volume increased 4 – 5 times. The reason for increased succulence was a higher ion-concentration of, and osmotic adjustment with, Na+ and Cl-. P. acaciae showed a high morphological and ecophysiological plasticity enabling to cope with salt stress and can be classified as a facultative eu-halophyte, which increases its halo-succulence according to the host. Host-parasite-associations are a model system for investigation of halophytes under different salt stress conditions.
Veste, M., Todt, H., Breckle, S.-W. (2015): Influence of halophytic hosts on their parasites – the case of Plicosepalus acaciae
Annals of Botany Plants: plu084, doi: 10.1093/aobpla/plu084