Host compatibility of the cloud forest mistletoe Psittacanthus schiedeanus (Loranthaceae) in Central Veracruz, Mexico

Abstract

The consequences of the seed deposition of the parasitic mistletoe Psittacanthus schiedeanus were evaluated in a 32-mo study. We conducted a field seed inoculation experiment to determine variation in seed adhesion, seed germination, seedling establishment, and plant survival to reproduction among five host species and to evaluate whether these post-dispersal processes explain mistletoe prevalence and specificity at the regional scale. Seeds without an exocarp were inoculated onto branches of individuals of the five most common host species identified in nature in central Veracruz, México. Seed fate was monitored for 2 yr, at weekly intervals for the first 2 mo and at 2-mo intervals thereafter. The height and diameter of experimental host branches and canopy cover above them were measured to see if these factors affected mistletoe establishment. Significant differences in seed attachment and seed germination were found among host species. Fewer seeds remained attached on experimental branches of Quercus germana than those of Liquidambar styraciflua, Acacia pennatula, and Platanus mexicana. Although significant differences in seed germination were observed among species (significantly greater on A. pennatula), >70% of mistletoe seeds germinated within the first 5 wk on all host species. Towards the end of the inoculation experiment, more mistletoe seedlings survived, grew, and then flowered on Liquidambar styraciflua than on A. pennatula, P. mexicana, Q. germana, or Q. leiophylla. Host branch initial height and diameter did not affect seedling survival, but seedlings survived better on trees where the canopy was more open. Our results suggest that Liquidambar styraciflua is the most compatible host species with P. schiedeanus in central Veracruz. Not surprisingly, Liquidambar is by far the most common host tree for P. schiedeanus in this area as well. We suggest that the observed local specialization is a result of seed dispersal as consequence of bird foraging and territorial behavior, host abundance, and host species compatibility.

Mistletoes: Pathology, Systematics, Ecology, and Management

“…Some dwarf mistletoes are so host specific that it has been suggested that their host specificity may be a useful taxonomic character for distinguishing between host populations (87,137). Although host specificity is commonly mentioned in the mistletoe literature, and many authors have pointed to its importance to pathology, few investigations have examined the mechanisms that control mistletoe-host compatibility (7,50,100,157,188,208,227,228,229). A better understanding of the mechanisms related to host specificity would have applications to mistletoe control, particularly in developing greater host resistance (196).…”

A mistletoe tale: postglacial invasion of Psittacanthus schiedeanus (Loranthaceae) to Mesoamerican cloud forests revealed by molecular data and species distribution modeling

“…The existence of host-specific relationships through cross-dispersal experiments has been suggested as evidence for the presence of host-specific races in a number of mistletoe species (e.g., [ 15 – 21 ]), or by using genetic markers, including isozymes [ 22 – 26 ], AFLPs [ 27 ] and chloroplast DNA sequences [ 6 , 7 , 28 , 29 ]. Cross-dispersal experiments have shown that seedling development is greatest when mistletoe seeds are placed on their source host species [ 15 – 17 , 20 , 21 , 30 , 31 ]. Using genetic data, however, the distinct host races identified were geographically isolated by some distance (except [ 25 , 26 ]) or the phylogeographic groups were best explained by isolation linked to Pliocene geological events and Pleistocene climate changes [ 6 , 7 ], which makes it difficult to distinguish between the potential effects of isolation and those linked to changes in host-tree availability on population divergence.…”

Development and characterization of microsatellite loci in the mistletoe Psittacanthus schiedeanus (Loranthaceae)

“…& Schlecht.) G. Don is characteristic of the canopy in the cloud forest edges in Mesoamerica and often parasitizes tall trees ( López de Buen and Ornelas, 2002 ). The hermaphroditic, hummingbird-pollinated flowers are self-compatible ( Ramírez and Ornelas, 2010 ), and ripe, lipid-rich, purplish-black fleshy fruits are dispersed by a variety of resident and migratory bird species ( López de Buen and Ornelas, 1999 , 2001 ; Ramírez and Ornelas, 2009 ).…”