Establishment of a Genetically Diverse, Disease-Resistant Acacia koa A. Gray Seed Orchard in Kokee, Kauai: Early Growth, Form, and Survival

Dudley, Nicklos S.; Jones, Tyler; Gerber, Kaitlin; Ross‐Davis, Amy L.; Sniezko, Richard A.; Cannon, Phil; Dobbs, Joe

doi:10.3390/f11121276

Cited by 9 publications

(4 citation statements)

References 13 publications

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“…Extensive areas of koa forests, especially in more mesic higher elevation areas, have been converted to alternative land uses via logging, grazing, and, more recently, fire and introduced pests and diseases, such as koa wilt disease ( Fusarium spp.). These threats have severely reduced populations at lower elevations (Gardner, 1980 ; Wilkinson and Elevitch, 2003 ; Elevitch et al, 2006 ; Dudley et al, 2020 ). In the past decade, the native koa moth ( Scotorythra paludicola ) also caused wide spread defoliation of koa on Hawai‘i Island and significant koa mortality (Stein and Scowcroft, 1984 ; Banko et al, 2014 ).…”

Section: Methodsmentioning

confidence: 99%

Intraspecific Variation Along an Elevational Gradient Alters Seed Scarification Responses in the Polymorphic Tree Species Acacia koa

Sugiyama¹,

Friday

Giardina³

et al. 2021

Front. Plant Sci.

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Physical dormancy in seeds can challenge restoration efforts where scarification conditions for optimal germination and seedling vigor are unknown. For species that occur along wide environmental gradients, optimal scarification conditions may also differ by seed source. We examined intraspecific variation in optimal scarification conditions for germination and seedling performance in koa (Acacia koa), which occurs across a wide range of environmental conditions. To evaluate scarification responses, we recorded imbibition percentage, germination percentage, germination time, seedling abnormalities, early mortality, seedling growth, and seedling survivorship. From these, we developed a scarification index (SI) that integrates these measures simultaneously. We hypothesized that seeds from lower elevation sources exposed to higher temperatures would have harder seed coats and would require more intense scarification treatments. To test this hypothesis, we repeatedly exposed seeds to hot water differing in temperature and time until seeds imbibed. Supporting the hypothesis, seeds from lower elevation sources generally required more intense scarification, although we found substantial variation among sources. Koa seeds germinated in about a week following imbibition. Boiling seeds (i.e., maintaining at 100°C) was effective for imbibing seeds but it also substantially reduced germination percentages. Repeated exposure to 90 to 100°C water did not reduce germination percentage but decreased seedling performance and increased early mortality. No seeds remained unimbibed after six attempts of boiling germinated whereas seeds remaining unimbibed after 15 attempts of exposure to 90 to 100°C water showed high germination percentages. Abnormalities in seedling development were rare but increased with treatment intensity. Exposure to 100°C water for 1 min overall generated the best SI values but the best treatment differed by elevation, and the treatment with the best SI was rarely predicted from the highest germination percentages. Seeds that imbibed without any treatment germinated at the same level as manually filed seeds but produced poor seedling quality. Variation in mother tree environments along an elevational gradient can lead to differences in seed coat characteristics, which may explain differing responses to treatments. Scarification treatments affected processes beyond imbibition and germination and using an index like SI may improve efficiency by identifying optimal scarification treatments while reducing seed waste.

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Section: Methodsmentioning

confidence: 99%

Intraspecific Variation Along an Elevational Gradient Alters Seed Scarification Responses in the Polymorphic Tree Species Acacia koa

Sugiyama¹,

Friday

Giardina³

et al. 2021

Front. Plant Sci.

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“…Chamaecyparis lawsoniana, which is expected to be unlisted from its threatened species designation in the near future (53,66,207,209). Disease resistant populations of Castanea dentata, Ulmus americana, and more recently Fraxinus spp., are also in various stages of Williams, Ginzel, Ma…”

Section: Wingfield and Bonellomentioning

confidence: 99%

The Global Forest Health Crisis: A Public Good Social Dilemma in Need of International Collective Action

Williams¹,

Ginzel²,

Ma³

et al. 2022

Preprint

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Society is confronted by interconnected threats to ecological sustainability. Among these is the devastation of forests by destructive non-native pathogens and insects introduced through global trade, leading to the loss of critical ecosystem services and a global forest health crisis. We argue that the forest health crisis is a public good social dilemma and propose a response framework that incorporates principles of collective action. This framework will enable scientists to better engage policymakers and empower the public to advocate for proactive biosecurity and forest health management. Collective action in forest health will feature broadly inclusive stakeholder engagement to build trust and set goals; accountability for destructive pest introductions; pooled support for weakest-link partners; and inclusion of intrinsic and non-market values of forest ecosystems in risk assessment. We provide short-term and longer-term measures that incorporate the above principles to shift the societal and ecological forest health paradigm to a more resilient state.

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“…There is significant momentum to restore koa forests (Pejchar., 2006) and understanding the environmental and genetic factors that limit survival and growth of planted koa may improve the success of conservation and reforestation efforts. Koa grown at lower elevations must contend with heat and drought stress (less than 250 mm annual rainfall in some areas; Gugger et al, 2018), as well as susceptibility to koa wilt disease (Dudley et al 2020). At higher elevation sites, the climate is relatively unpredictable in terms of nighttime winter freezing temperatures (Lipp et al, 1994; Rose et al, 2020) and cold susceptibility is a key limiting factor for koa regeneration.…”

Section: Introductionmentioning

confidence: 99%

Integrative analysis of physiology and genomics provides insights into freeze tolerance adaptations of Acacia koa along an elevational cline

Ebrahimi,

Sugiyama,

Ayala‐Jacobo

et al. 2023

Physiologia Plantarum

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Natural selection for plant species in heterogeneous environments creates genetic variation for traits such as cold tolerance. While physiological or molecular analyses have been used to evaluate stress tolerance adaptations, combining these approaches may provide deeper insight. Acacia koa (koa) occurs from sea level to 2300 m in Hawaiʻi, USA. At high elevations, natural koa populations have declined due to deforestation, and freeze tolerance is a limiting factor for tree regeneration. We used physiology and molecular analyses to evaluate cold tolerance of koa populations from low (300–750 m), middle (750–1500 m), and high elevations (1500–2100 m). Half of the seedlings were cold acclimated by exposure to progressively lowered air temperatures for eight weeks (from 25.6/22.2°C to 8/4°C, day/night). Using the whole plant physiology‐freezing test and koa C‐repeat Binding Factor CBF genes, our results indicated that koa can be cold‐acclimated when exposed to low, non‐freezing temperatures. Seedlings from high elevations had consistently higher expression of Koa CBF genes associated with cold tolerance, helping to explain variation in cold‐hardy phenotypes. Evaluation of the genetic background of 22 koa families across the elevations with low coverage RNA sequencing indicated that high elevation koa had relatively low values of heterozygosity, suggesting that adaptation is more likely to arise in the middle and low elevation sources. This physiology and molecular data for cold tolerance of koa across the elevation gradient of the Hawaiian Islands provides insights into natural selection processes and may help to support guidelines for conservation and seed transfer in forest restoration efforts.

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Establishment of a Genetically Diverse, Disease-Resistant Acacia koa A. Gray Seed Orchard in Kokee, Kauai: Early Growth, Form, and Survival

Cited by 9 publications

References 13 publications

Intraspecific Variation Along an Elevational Gradient Alters Seed Scarification Responses in the Polymorphic Tree Species Acacia koa

Intraspecific Variation Along an Elevational Gradient Alters Seed Scarification Responses in the Polymorphic Tree Species Acacia koa

The Global Forest Health Crisis: A Public Good Social Dilemma in Need of International Collective Action

Integrative analysis of physiology and genomics provides insights into freeze tolerance adaptations of Acacia koa along an elevational cline

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