Host-race specificity in the endemic pygmy mistletoe Korthalsella salicornioides (Viscaceae) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology at Massey University, Palmerston North, New Zealand
Loading...
Date
2016
DOI
Open Access Location
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Massey University
Rights
The Author
Abstract
Korthalsella Tiegh. is a genus of stem hemiparasites in the family Viscaceae, represented in
New Zealand by three endemic species: K. clavata, K. lindsayi, and K. salicornioides. The most
host-specific is K. salicornioides as it parasitizes two main host genera Leptospermum
(Myrtaceae) and Kunzea (Myrtaceae), while the other two species are considered generalists
parasitizing a wider range of host species. K. salicornioides is naturally uncommon and sparse,
although it can be locally abundant on occasion. Mistletoe populations are at risk primarily
due to habitat destruction and subsequent loss of hosts. Cross-infection experiments in K.
salicornioides provided some insight into the presence of putative host races, as better
mistletoe seedling establishment success rates were apparent when the maternal and
recipient hosts were the same. However, because previous molecular sequence data (nuclear
internal transcribed spacers and chloroplast trnQ-rps16) for K. salicornioides were not
informative about specific host-races, more rapidly evolving molecular markers might be
expected to detect host races.
In this study, next generation sequencing was used to develop novel microsatellite
markers for Korthalsella. Eleven markers were reliably amplifiable and the most polymorphic
for K. salicornioides were used to genotype 272 K. salicornioides individuals from 16
populations. Across all populations few alleles were identified, and within-population
assessment of genetic variation indicated that many populations have low levels of genetic
diversity and high proportions of homozygotes. Despite the presence of few alleles, a high
degree of genetic differentiation between most populations was detected and was found to
reflect host species and geography.
The findings of this study that Korthalsella salicornioides populations have low levels of
genetic variation but host-specific races, has important conservation implications. The main
conservational focus should be maintaining and increasing host Leptospermum and Kunzea
populations. The spread of mistletoe seed on hosts within or between populations may also
increase the chances of continued survival. However, it is imperative that genetic material
comes from the same host species, and consideration should also be given to the geographic
area, especially in the Wairarapa. This study provides insights into the population structure
within and between the different host populations and suggests several interesting areas of
future study.
Description
Keywords
Mistletoes, Korthalsella salicornioides, Genetics, Host plants, Host-parasite relationships, New Zealand, Research Subject Categories::NATURAL SCIENCES::Biology::Organism biology::Plant physiology, Conservation