Protecting tree species is essential for maintaining biodiversity, ensuring ecosystem stability, and supporting future reforestation and adaptation to climate change. Trees play a crucial role in global ecological balance, carbon sequestration, and provide habitat for countless organisms. The in vitro conservation of trees using nonembryonic tissues and organs has emerged as a vital strategy for protecting genetic diversity, yet it faces significant challenges. These methods are grounded in controlled, sterile environments that minimize space requirements and allow for the preservation of germplasm regardless of season and climate regimes. Slow-growth storage (SGS) techniques have proven effective for medium-term preservation because they reduce metabolic activity and minimize the need for subculturing, therefore lowering contamination risks and operating costs. Synthetic seeds, i.e., the encapsulation of plant propagules within protective matrices, offer an innovative approach for storing and transporting germplasm, particularly for large-scale conservation programs. Cryopreservation, involving ultralow-temperature storage, further complements these methods by enabling the long-term preservation of diverse tree germplasms in the form of somatic tissue samples (e.g., buds, meristems, and nodes). Significant advancements have been made in this field, including the development of modern techniques such as droplet vitrification, encapsulation–dehydration, and cryoplate-based combinations. Despite the potential of tissue culture techniques to preserve genetic diversity, issues such as low explant survival rates, endophyte outbreaks, and ethylene production remain critical obstacles. Innovative solutions, including the use of silver thiosulfate to inhibit ethylene production or screening for endophyte-control methods, are being explored to improve the final outcomes. However, cryopreservation remains species-specific and complex, with challenges related to recalcitrant tissues, post-thaw recovery, and protocol optimization. The need for user-friendly, cost-effective protocols further complicates implementation. Advances in genetic engineering, such as CRISPR-Cas9, and knowledge from postgenomic research hold promise for enhancing dehydration tolerance and improving the viability of cryopreserved tissues. Additionally, the integration of high-throughput screening methods facilitates the identification of optimal cryoprotocols and storage conditions. Prospects include establishing global cryobank networks for effective germplasm exchange and engaging indigenous communities to incorporate traditional knowledge into conservation strategies. This chapter summarizes the present knowledge on the in vitro-based conservation methods applied to trees.

Progress, Challenges, and Prospects of In Vitro Conservation of Tree Species Using Nonembryonic Tissue and Organs

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发表日期：

2025年

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Dariusz Kulus

摘要

Protecting tree species is essential for maintaining biodiversity, ensuring ecosystem stability, and supporting future reforestation and adaptation to climate change. Trees play a crucial role in global ecological balance, carbon sequestration, and provide habitat for countless organisms. The in vitro conservation of trees using nonembryonic tissues and organs has emerged as a vital strategy for protecting genetic diversity, yet it faces significant challenges. These methods are grounded in controlled, sterile environments that minimize space requirements and allow for the preservation of germplasm regardless of season and climate regimes. Slow-growth storage (SGS) techniques have proven effective for medium-term preservation because they reduce metabolic activity and minimize the need for subculturing, therefore lowering contamination risks and operating costs. Synthetic seeds, i.e., the encapsulation of plant propagules within protective matrices, offer an innovative approach for storing and transporting germplasm, particularly for large-scale conservation programs. Cryopreservation, involving ultralow-temperature storage, further complements these methods by enabling the long-term preservation of diverse tree germplasms in the form of somatic tissue samples (e.g., buds, meristems, and nodes). Significant advancements have been made in this field, including the development of modern techniques such as droplet vitrification, encapsulation–dehydration, and cryoplate-based combinations. Despite the potential of tissue culture techniques to preserve genetic diversity, issues such as low explant survival rates, endophyte outbreaks, and ethylene production remain critical obstacles. Innovative solutions, including the use of silver thiosulfate to inhibit ethylene production or screening for endophyte-control methods, are being explored to improve the final outcomes. However, cryopreservation remains species-specific and complex, with challenges related to recalcitrant tissues, post-thaw recovery, and protocol optimization. The need for user-friendly, cost-effective protocols further complicates implementation. Advances in genetic engineering, such as CRISPR-Cas9, and knowledge from postgenomic research hold promise for enhancing dehydration tolerance and improving the viability of cryopreserved tissues. Additionally, the integration of high-throughput screening methods facilitates the identification of optimal cryoprotocols and storage conditions. Prospects include establishing global cryobank networks for effective germplasm exchange and engaging indigenous communities to incorporate traditional knowledge into conservation strategies. This chapter summarizes the present knowledge on the in vitro-based conservation methods applied to trees.