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Item Rhododendron diversity conservation in global botanic gardens: A case study of Maddenia species(Cambridge University Press on behalf of Fauna & Flora International, 2024-11-04) Hu L; MacKay M; Gardiner SE; Tate JAEffective ex situ conservation of plants in botanic gardens requires sufficient wild accessions to represent wild diversity. In Rhododendron L. (Ericaceae), c. 64% of the taxa are threatened or require field investigation. As a case study of the analysis of ex situ conservation gaps we used ecogeographical representation as a proxy for genetic representation in ex situ collections of the 65 taxa of Rhododendron subsection Maddenia. We compiled the first list profiling both wild distributions and ex situ wild collections of all taxa in subsection Maddenia. Our results reveal that 55 Maddenia taxa are in cultivation. Of the 18 threatened taxa all are in cultivation but nine require further collection to capture adequate wild diversity. There are 12 Data Deficient taxa: These await further field investigation of wild populations and nine of them require wild collections to conserve genetic diversity. The UK, the USA, Australia, New Zealand and China are the top five countries holding ex situ collections of subsection Maddenia; in these countries nearly 66% of the ex situ sites hold > 86% of the global living collections of subsection Maddenia. We recommend that wild collections of endemic species of subsection Maddenia should be established in all 10 countries of origin and that data should be shared internationally for metacollections. In addition to proposing priorities, our case study highlights the challenges facing data and collection management to help achieve effective ex situ conservation for Rhododendron species.Item Rhododendron taxonomy and diversity of ex situ collections for conservation : (subsection) Maddenia species as a case study : a thesis presented in the partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Agriculture and Horticulture at Massey University (Manawatū campus], Palmerston North, New Zealand(Massey University, 2024-02-01) Hu, LingIn the ‘big genus’ Rhododendron of over 1,000 species, more than half of the species are threatened, at risk, or lacking data for biodiversity conservation. Ex situ collections, especially those from the wild, are crucial for safeguarding the diversity of species. However, lack of knowledge on existing wild diversity in botanic garden collections, and complex taxonomy, are two main problems in species assessments and conservation decision making. This research studied subsection Maddenia, a group of ~65 taxa encountering the two problems but seldom studied, as an exemplar to investigate species taxonomy and ex situ diversity. An ex situ conservation gap analysis was undertaken, using ecogeographical representation as a proxy for genetic representation in current botanic garden collections worldwide. Fifty-five of the total 65 taxa were found in cultivation, with over 86% of the living collections conserved in 66% of global botanic gardens. Half of the 18 threatened taxa, and nine of the 12 Data Deficient taxa require further wild collection to achieve a minimum level of ecogeographical representation in ex situ collections. Occurrence of ex situ collections in countries of origin is limited, and the distribution of ex situ collections worldwide is northern hemisphere centric. The results highlight the necessity of having more ex situ collections in the 10 native countries, and the importance of inter-institutional data sharing and robust documentation of collections. Determination of ploidy level of species was the second study, as the presence of polyploid samples may affect phylogenetic analysis. Ploidy levels were estimated for 263 accessions of 47 taxa (including 135 wild accessions) using flow cytometry. Meiotic chromosomes were counted for representative species of both diploids and polyploids to verify the flow cytometry results. This study showed that all taxa except one were diploid. The exception was that polyploids (2–8x, 12x) occur in the R. maddenii complex, where only seven of the 62 accessions tested were diploid while the rest were polyploid. This high level of polyploidy, combined with (i) the wide geographical distribution of the R. maddenii complex, and (ii) the previous ‘lumping’ of 12 taxa into the two subspecies, suggests the possibility of either some cryptic species or the need to re-evaluate some of the synonymized species. If new species were revealed, some may require conservation action. However, a greater number of wild-collected accessions and of different geographic origins are needed to explore this possibility. Following the ploidy study, molecular phylogeny of 40 taxa, including diploids and polyploids, was analysed using target capture sequencing. Phylogenetic trees from maximum likelihood and Bayesian analyses largely supported the morphological groupings of the Maddenii Series, Ciliicalyx Subseries and Megacalyx Subseries, but not the Ciliatum Subseries as classified by Davidian (1982). Of particular interest was the clustering in one clade of all of the R. maddenii complex, including all polyploid samples. This occurred irrespective of the method of analysis; however, there was no clear pattern of relationships to ploidy levels within the clade. The molecular phylogeny delimited several species and suggested a revision of the boundary of ‘subsection Maddenia’, although further research, to include a wider range of species, is needed to determine whether the new boundaries should be wider or narrower than before. The feasibility of using controlled pollination for safeguarding germplasm of prioritised species in ex situ collections was studied. Fruit set and seed germination identified the self- and cross-incompatibility of R. excellens (Vulnerable), which requires methods other than controlled pollination to conserve the intraspecific diversity in botanic gardens. R. dalhousiae var. dalhousiae (Least Concern), R. dalhousiae var. rhabdotum (Vulnerable), R. lindleyi (Least Concern), and R. nuttallii (Near Threatened) were both self- and cross-compatible, but the compatibility between self and cross pollinations differed from taxon to taxon and from accession to accession. These results suggest the choice of intraspecific pollination should be tested for each species before a programme of propagation is initiated. These aspects studied for subsection Maddenia can be immediately applied to conservation of this group of plants by working with the Global Conservation Consortium for Rhododendron. Meanwhile, the methods used here provide an exemplar for investigating other Rhododendron species or plant groups that encounter similar problems, to guide conservation efforts.Item Ex situ conservation of orchid seeds of the Lycaste genus : a thesis presented in partial fulfilment of the requirements for the degree of Master of Sciences in Plant Breeding at Massey University, (Manawatū campus) Palmerston North, New Zealand(Massey University, 2022) Alfaro Pinto, Maria AlejandraThe orchid family (Orchidaceae) is the second largest family in the plant kingdom with about 28000 species. Most orchid species are endangered. Both in situ and ex situ approaches are necessary for the conservation of endangered and threatened species, including orchids. In situ conservation should be the priority, however, ex situ conservation can complement initiatives to ensure species survival in situ. More information on orchid seed dispersal mechanisms, pollination, and germination biology is needed to support conservation efforts. This study included three endangered species from Mesoamerica, Lycaste virginlis, L. cochleata, and L. lasioglossa that should be considered a high conservation priority. The primary intention of the different experiments was to contribute information that favours seed conservation of endangered orchid species from the Mesoamerica biodiversity hotspot. For this, characterization of the seed capsule morphology and seed micro-morphological traits were investigated followed by the assessment of the effect of three media on in vitro asymbiotic seed germination and the viability and germination of the seeds under different storage conditions. The qualitative traits of the seed capsules and the seeds were similar in appearance and colour for the three Lycaste species evaluated. However, high variability was found in the quantitative traits of both seed capsules and seeds. Based on the micro-morphological traits’ findings, it is possible to speculate that these three epiphytic Lycaste species which all grow under dense tropical canopies are dispersed by water drops falling onto the orchid plant from the canopy and by gravity. This suggestion is consistent with their having small-sized seeds, relatively large embryos, and low air volume (in comparison with other epiphytic and terrestrial orchid species). Specifically, those traits may allow the seeds to be dispersed in vegetation-dense and humid natural environments. Further research needs to be done to validate these findings, including more species of the Lycaste genus. For the successful implementation of conservation plans, it is important to understand the specific nutritional requirements for seed germination of the target species. This study assessed three different germination media (Murashige and Skoog (MS), Knudson C, and terrestrial orchid medium BM-1) to identify the most suitable one for asymbiotic in vitro germination. The germination percentages and seedling development significantly varied across the three Lycaste species. MS media sustained the highest germination percentages with high-quality plantlets (in stage 4). Still, germination did not reach the potential suggested by the tetrazolium test for viability, meaning that further media optimization is required. Knudson C media was also a good option for the seed germination and seedling development for two of the three species (L. cochleata and L. lasioglossa). The effect of different storage conditions (temperature, RH, and time) on seed viability and germinability was tested. The differential scanning calorimetry (DSC) method was used to identify each species' lipid melting and crystallization points. Based on the DSC findings, storage temperatures below -75°C is recommended for the storage of three Lycaste species. Still, further research needs to be done by testing more and different storage temperatures to validate these findings.Item Rhododendron in New Zealand and ex situ conservation.MacKay MThis presentation outlines the New Zealand ex situ Rhododendron Conservation Project, its relationship to the Global Conservation Consortium, and practical steps that collection managers can take to support conservation.