Invited Mini-Review Research Topic: Utilization of Protoplasts to Facilitate Gene Editing in Plants: Schemes for In Vitro Shoot Regeneration From Tissues and Protoplasts of Potato and Rapeseed: Implications of Bioengineering Such as Gene Editing of Broad-Leaved Plants

A quest for the potato of the future: characterization of wild tuber-bearing Solanum species for de novo domestication

Potato (Solanum tuberosum) is a staple food worldwide, but modern potato cultivation relies heavily on the use of pesticides to control pests and diseases. However, many wild Solanum species are highly resistant to biotic and abiotic stresses relevant to potato production. Several of those species have been used in potato breeding to confer resistance but this has only been moderately successful. Instead, we propose an alternative approach to utilize the potential of wild Solanum germplasm. Recently, de novo domestication has been suggested to produce more resilient crops: instead of introducing resistance genes into existing crops, domestication traits could be introduced into resistant wild crop relatives to create new crops. Therefore, we selected 10 promising species from the 107 known wild tuber-bearing Solanum species for their resistance to biotic and abiotic stresses. Selection was based on the existing literature, characterizing species by tuberization under short- and long-day conditions, tuber glycoalkaloid content, starch digestibility and performance in tissue culture. Based on this, the highly pest- and disease-resistant S. bulbocastanaum was chosen. Our results showed that it produced relatively large tubers, also under long-day conditions, and performed exceptionally well in tissue culture.

Strategies and Protocols for Optimized Genome Editing in Potato

The potato family includes a highly diverse cultivar repertoire and has a high potential for nutritional yield improvement and refinement but must in line with other crops be adapted to biotic and abiotic stresses, for example, accelerated by climate change and environmental demands. The combination of pluripotency, high ploidy, and relative ease of protoplast isolation, transformation, and regeneration together with clonal propagation through tubers makes potato highly suitable for precise genetic engineering. Most potato varieties are tetraploid having a very high prevalence of length polymorphisms and small nucleotide polymorphisms between alleles, often complicating CRISPR-Cas editing designs and strategies. CRISPR-Cas editing in potato can be divided into (i) characterization of target area and in silico-aided editing design, (ii) isolation and editing of protoplast cells, and (iii) the subsequent explant regeneration from single protoplast cells. Implementation of efficient CRISPR-Cas editing relies on efficient editing at the protoplast (cell pool) level and on robust high-throughput editing scoring methods at the cell pool and explant level. Gene and chromatin structure are additional features to optionally consider. Strategies and solutions for addressing key steps in genome editing of potato, including light conditions and schemes for reduced exposure to hormones during explant regeneration, which is often linked to somaclonal variation, are highlighted.

Efficient regeneration of protoplasts from Solanum lycopersicum cultivar Micro-Tom

Protoplast regeneration has become a key platform for genetic and genome engineering. However, we lack reliable and reproducible methods for efficient protoplast regeneration for tomato (Solanum lycopersicum) cultivars. Here, we optimized cell and tissue culture methods for protoplast isolation, microcallus proliferation, shoot regeneration, and plantlet establishment of the tomato cultivar Micro-Tom. A thin layer of alginate was applied to protoplasts isolated from third to fourth true leaves and cultured at an optimal density of 1 × 105 protoplasts/ml. We determined the optimal culture media for protoplast proliferation, callus formation, de novo shoot regeneration, and root regeneration. Regenerated plantlets exhibited morphologically normal growth and sexual reproduction. The entire regeneration process, from protoplasts to flowering plants, was accomplished within 5 months. The optimized protoplast regeneration platform enables biotechnological applications, such as genome engineering, as well as basic research on plant regeneration in Solanaceae species.

Research progress and applications of colorful Brassica crops

MAIN CONCLUSION

We review the application and the molecular regulation of anthocyanins in colorful Brassica crops, the creation of new germplasm resources, and the development and utilization of colorful Brassica crops. Brassica crops are widely cultivated: these include oilseed crops, such as rapeseed, mustards, and root, leaf, and stem vegetable types, such as turnips, cabbages, broccoli, and cauliflowers. Colorful variants exist of these crop species, and asides from increased aesthetic appeal, these may also offer advantages in terms of nutritional content and improved stress resistances. This review provides a comprehensive overview of pigmentation in Brassica as a reference for the selection and breeding of new colorful Brassica varieties for multiple end uses. We summarize the function and molecular regulation of anthocyanins in Brassica crops, the creation of new colorful germplasm resources via different breeding methods, and the development and multifunctional utilization of colorful Brassica crop types.