Defining exceptional species—A conceptual framework to expand and advance ex situ conservation of plant diversity beyond conventional seed banking

Pence, Valerie C.; Meyer, Abby; Linsky, Jean; Gratzfeld, Joachim; Pritchard, Hugh W.; Westwood, Murphy; Bruns, Emily Beckman

doi:10.1016/j.biocon.2021.109440

Cited by 33 publications

(32 citation statements)

References 71 publications

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“…There were 19 exceptional families for which no articles were found in the literature search, representing 152 species, or 20% of the List of Exceptional Plants (Table 6). When these were examined for the reason for their exceptionality (their exceptionality factor or EF; [11]), the highest proportion of these were EF2 (desiccation sensitive/recalcitrant) (70%), followed by EF3 (freeze-sensitive/short-lived) (26%). Dipterocarpaceae was the family with the most exceptional species (59) with no literature in the Web of Science search, and 55 or 93% of these were classified as EF2.…”

Section: Resultsmentioning

confidence: 99%

“…Species with desiccation sensitive (recalcitrant) seeds, for example, cannot undergo the drying required for seed banking, and a recent study indicated that such species are projected to make up more than a quarter of threatened species [10]. These and other species, such as those without adequate seeds for banking or seeds that are short-lived in storage, pose challenges to conventional seed banking and are known as exceptional species [11].…”

Section: Introductionmentioning

confidence: 99%

“…Exceptionality factors (EFs) of the species within each family are also provided. EF1 = few or no seeds; EF2 = desiccation sensitive seeds; EF3 = short-lived seeds; EF4 = seeds deeply dormant[11]. Shaded cells indicate non-zero values.…”

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confidence: 99%

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The Tip of the Iceberg: Cryopreservation Needs for Meeting the Challenge of Exceptional Plant Conservation

Pence

Bruns

2022

Plants

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Cryopreservation is increasingly important as a conservation tool, particularly for threatened exceptional species. The goal of this study was to investigate the current knowledge of plant cryopreservation through a search of the literature in Web of Science and align that with the 775 species currently identified on the Working List of Exceptional Plants. While there is a good foundation in plant cryopreservation research, particularly with economically important species, there are significant gaps in research on families that contain the largest numbers of currently known exceptional species, including the Dipterocarpaceae, Rhizophoraceae, and Pittosporaceae. Even families well represented in both in the literature and on the List of Exceptional Plants had much less overlap at the level of genus. Tropical trees, a significant portion of exceptional species, were not as well represented in the literature as herbaceous species. Over 70% of all articles dealt with in vitro cryopreservation, with much less emphasis on other methods (seed, embryo, dormant bud, and pollen) that will be more cost-effective for species where they can be applied. While the research on plant cryopreservation to date provides a strong foundation and is being utilized effectively for conserving the diversity of a number of economically important species, this study revealed significant gaps that can help prioritize future research to more effectively conserve the diversity of threatened exceptional species.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Tip of the Iceberg: Cryopreservation Needs for Meeting the Challenge of Exceptional Plant Conservation

Pence

Bruns

2022

Plants

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“…Unfortunately, many other species can be described as "exceptional" which means that their seeds cannot be stored under conventional seed bank conditions. It is estimated that one-third of all exceptional species globally are threatened with extinction [7,8]. Four main requirements need to be met for successful seed banking, and species designated as exceptional are placed into different groups based on which of the four Exceptional Factors (EF) is the most predominant [7].…”

Section: Introductionmentioning

confidence: 99%

“…Four main requirements need to be met for successful seed banking, and species designated as exceptional are placed into different groups based on which of the four Exceptional Factors (EF) is the most predominant [7]. The second largest EF group (EF3) of known exceptional species (36.6%) are characterized as species producing short-lived seeds [8]. Fundamental knowledge about the progressive loss of seed viability during storage is based on studies conducted in crops and model species (Arabidopsis thaliana L.) which produce orthodox seeds with a relatively long lifespan [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

DNA Methylation as an Early Indicator of Aging in Stored Seeds of “Exceptional” Species Populus nigra L.

Michalak

Plitta-Michalak

Naskręt-Barciszewska

et al. 2022

Cells

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Ex situ preservation of genetic resources is an essential strategy for the conservation of plant biodiversity. In this regard, seed storage is the most convenient and efficient way of preserving germplasm for future plant breeding efforts. A better understanding of the molecular changes that occur during seed desiccation and aging is necessary to improve conservation protocols, as well as real-time methods for monitoring seed quality. In the present study, we assessed changes in the level of genomic 5-methylcytosine (5mC) in seeds of Populus nigra L. by 2D-TLC. Epigenetic changes were characterized in response to several seed storage regimes. Our results demonstrate that P. nigra seeds represent an intermediate type of post-harvest behavior, falling between recalcitrant and orthodox seeds. This was also true for the epigenetic response of P. nigra seeds to external factors. A crucial question is whether aging in seeds is initiated by a decline in the level of 5mC, or if epigenetic changes induce a process that leads to deterioration. In our study, we demonstrate for the first time that 5mC levels decrease during storage and that the decline can be detected before any changes in seed germination are evident. Once P. nigra seeds reached an 8–10% reduction in the level of 5mC, a substantial decrease in germination occurred. The decline in the level of 5mC appears to be a critical parameter underlying the rapid deterioration of intermediate seeds. Thus, the measurement of 5mC can be a fast, real-time method for assessing asymptomatic aging in stored seeds.

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Supporting long‐term sustainability of ex situ collections using a pedigree‐based population management approach

et al. 2022

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Premise Living collections maintained for generations are at risk of diversity loss, inbreeding, and adaptation to cultivation. To address these concerns, the zoo community uses pedigrees to track individuals and implement crosses that maximize founder contributions and minimize inbreeding. Using a pedigree management approach, we demonstrate how conducting strategic crosses can minimize genetic issues that have arisen under current practices. Methods We performed crosses between collections and compared progeny fitness, including plant performance and reproductive health. We genotyped the progeny and parental accessions to measure changes in diversity and relatedness within and between accessions. Results The mean relatedness values among individuals within each accession suggest they are full siblings, demonstrating that there was high inbreeding and low diversity within accessions, although less so among accessions. Progeny from the wider crosses had increased genetic diversity and were larger and more fertile, while self‐pollinated accessions were smaller and less fertile. Discussion Institutions that hold exceptional species should consider how diversity is maintained within their collections. Implementing a pedigree‐based approach to managing plant reproduction ex situ will slow the inevitable loss of genetic diversity and, in turn, result in healthier collections.

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Defining exceptional species—A conceptual framework to expand and advance ex situ conservation of plant diversity beyond conventional seed banking

Cited by 33 publications

References 71 publications

The Tip of the Iceberg: Cryopreservation Needs for Meeting the Challenge of Exceptional Plant Conservation

The Tip of the Iceberg: Cryopreservation Needs for Meeting the Challenge of Exceptional Plant Conservation

DNA Methylation as an Early Indicator of Aging in Stored Seeds of “Exceptional” Species Populus nigra L.

Supporting long‐term sustainability of ex situ collections using a pedigree‐based population management approach

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