Search

In vitro tissue culture technologies provide novel tools for improving plant production [...]

Root and tuber crops (RTCs) are the second-most important carbohydrate commodity after cereals. Many species of the RTCs are vegetatively propagated, making their shoot tips the preferred material to be conserved for future uses. Shoot tip cryopreservation provides an important tool to support the long-term conservation of plant genetic resources. Over the past four decades, significant efforts have been undertaken to move shoot tip cryopreservation of RTCs from research projects to full-scale implementation in cryobanks. This comprehensive review focuses on the history of cryopreservation protocols developed in RTCs. The encapsulation and vitrification solution-based cryopreservation techniques followed by ultra-rapid freezing and thawing have been highly successful. Additionally, different strategies for improving the cryotolerance of shoot tips have been introduced to further increase post-cryopreservation recovery. Finally, the research conducted to explain the mechanism underlying cryoprotection and differential cryotolerance including the use of histological studies are highlighted.

Abstract Lilium is one of the most popular flower crops worldwide, and some species are also used as vegetables and medicines. The availability of and easy access to diverse Lilium genetic resources are essential for plant genetic improvements. Cryopreservation is currently considered as an ideal means for the long-term preservation of plant germplasm. Over the last two decades, great efforts have been exerted in studies of Lilium cryopreservation and progress has been made in the successful cryopreservation of pollen, seeds and shoot tips in Lilium. Genes that exist in Lilium, including those that regulate flower shape, color and size, and that are resistant to cold stress and diseases caused by fungi and viruses, provide a rich source of valuable genetic resources for breeding programs to create novel cultivars required by the global floriculture and ornamental markets. Successful cryopreservation of Lilium spp. is a way to preserve these valuable genes. The present study provides updated and comprehensive information about the development of techniques that have advanced Lilium cryopreservation. Further ideas are proposed to better direct future studies on Lilium cryobiotechnology.

In vitro micrografting is an important technique supporting the micropropagation of a range of plant species, particularly woody plant species. Over the past several decades, in vitro micrografting has become a strategy to facilitate shoot recovery and acclimatization of in vitro-grown horticultural species. This review focuses on studies on horticultural crops over the past two decades that cover the establishment of in vitro micrografting, discusses factors affecting the success of in vitro micrografting, and provides commentary on the contribution of micrografting applications to the field of micropropagation. Considering the important roles of micrografting in the restoration of vigor and rooting competence, in promotion of shoot recovery following somatic embryogenesis and organogenesis, and in facilitation of shoot regrowth after cryopreservation, the potential use of this technique in facilitation of genetic engineering and safe conservation of horticultural species are specially highlighted.

This document, published in the journal Horticulturae, discusses the use of in vitro tissue culture technologies for plant regeneration, micropropagation, and germplasm conservation of horticultural crops. The document includes eleven publications that cover various aspects of in vitro plant regeneration and conservation. The studies focus on different plant species, such as Foxtail lily, Agapanthus praecox, Rhododendron decorum, and red-fleshed 'Da Hong' pitaya, and explore different techniques and protocols for micropropagation. The document also discusses the use of bioreactors, the application of silver nanoparticles, and the development of an in vitro incubation system for the safe exchange of plant germplasm. Additionally, the document highlights the importance of in vitro culture technologies for genetic improvements and long-term preservation of horticultural plant germplasm. The authors hope that the information presented in this document will contribute to further research and practical implementation of biotechnologies for crop improvement and germplasm conservation. [Extracted from the article]

Abstract Production of virus-free plants is necessary to control viral diseases, import novel cultivars from other countries, exchange breeding materials between countries or regions and preserve plant germplasm. In vitro techniques represent the most successful approaches for virus eradication. In vitro thermotherapy-based methods, including combining thermotherapy with shoot tip culture, chemotherapy, micrografting or shoot tip cryotherapy, have been successfully established for efficient eradication of various viruses from almost all of the most economically important crops. The present study reviewed recent advances in in vitro thermotherapy-based methods for virus eradication since the twenty-first century. Mechanisms as to why thermotherapy-based methods could efficiently eradicate viruses were discussed. Finally, future prospects were proposed to direct further studies.

Abstract Background Preservation of plant virus is a fundamental requirement in all types of virus-related research and applied applications. Development of efficient, reliable strategies for long-term preservation of plant virus would largely assist these studies. Results The present study reported a novel biotechnology allowing cryopreservation of Apple stem grooving virus (ASGV) in living shoot tips. Following cryopreservation by droplet-vitrification or encapsulation-dehydration, about 62–67% of shoot regrowth and 100% of ASGV cryopreservation were obtained. Although shoot proliferation and virus concentration were reduced in cryopreserved diseased shoots after 8 weeks of shoot regeneration, continuous subculture for 4 times (16 weeks) increased shoot proliferation and virus concentration to comparative levels as those produced by shoot tip culture (as a control to shoot tip cryopreservation). Cryopreserved ASGV was efficiently transmitted to a woody plant by micrografting and to a herbaceous indicator by mechanical inoculation. Gene sequencing in three fragments of ASGV genome including coat protein and movement protein showed that cryopreserved ASGV shared 99.87% nucleotide identities with shoot tip culture-preserved virus, indicating cryopreserved virus is genetically stable. Conclusions The present study demonstrates ASGV, a representative virus that can infect meristematic cells of shoot tips, can be efficiently cryopreserved in shoot tips. To the best of our knowledge, this is the first report on plant virus cryopreservation in living tissues, and has great potential applications to long-term preservation of plant viruses.

Grapevine (Vitis spp.) is one of the most economically important temperate fruit crops. Grapevine breeding programs require access to high-quality Vitis cultivars and wild species, which may be maintained within genebanks. Shoot tip cryopreservation is a valuable technique for the safe, long-term conservation of Vitis genetic resources that complements traditional field and in vitro germplasm collections. Vitis is highly susceptible to virus infections. Virus-free plants are required as propagation material for clonally propagated germplasm, and also for the global exchange of grapevine genetic resources. Shoot tip cryotherapy, a method based on cryopreservation, has proven to be effective in eradicating viruses from infected plants, including grapevine. This comprehensive review outlines/documents the advances in Vitis shoot tip cryopreservation and cryotherapy that have resulted in healthy plants with high regrowth levels across diverse Vitis species.

Cryopreservation is considered an ideal strategy for the long-term preservation of plant genetic resources. Significant progress was achieved over the past several decades, resulting in the successful cryopreservation of the genetic resources of diverse plant species. Cryopreservation procedures often employ in vitro culture techniques and require the precise control of several steps, such as the excision of explants, preculture, osmo- and cryoprotection, dehydration, freeze-thaw cycle, unloading, and post-culture for the recovery of plants. These processes create a stressful environment and cause reactive oxygen species (ROS)-induced oxidative stress, which is detrimental to the growth and regeneration of tissues and plants from cryopreserved tissues. ROS-induced oxidative stresses were documented to induce (epi)genetic and somatic variations. Therefore, the development of true-to-type regenerants of the source germplasm is of primary concern in the application of plant cryopreservation technology. The present article provides a comprehensive assessment of epigenetic and genetic integrity, metabolic stability, and field performance of cryopreserved plants developed in the past decade. Potential areas and the directions of future research in plant cryopreservation are also proposed.