Genetic Transformation of Hordeum vulgare ssp. spontaneum for the Development of a Transposon-Based Insertional Mutagenesis System

A Protocol for High-efficiency Transformation and Genome Editing in Elite Wheat Cultivars

CRISPR-Cas9-based editing offers a simple yet efficient method for introducing targeted mutations in the genes of interest. Low efficiency of transformation and a lack of reproducibility in editing genes in elite wheat cultivars are the bottlenecks in improving simply inherited traits. We describe a high-efficiency transformation protocol for editing elite wheat cultivars using JD633-GRF4-GIF1 CRISPR vector. This vector reduces the regeneration time of transformants to less than 90 days and enables transformation of elite cultivars.

Metabolic engineering-induced transcriptome reprogramming of lipid biosynthesis enhances oil composition in oat

The endeavour to elevate the nutritional value of oat (Avena sativa) by altering the oil composition and content positions it as an optimal crop for fostering human health and animal feed. However, optimization of oil traits on oat through conventional breeding is challenging due to its quantitative nature and complexity of the oat genome. We introduced two constructs containing three key genes integral to lipid biosynthesis and/or regulatory pathways from Arabidopsis (AtWRI1 and AtDGAT1) and Sesame (SiOLEOSIN) into the oat cultivar 'Park' to modify the fatty acid composition. Four homozygous transgenic lines were generated with a transformation frequency of 7%. The expression of these introduced genes initiated a comprehensive transcriptional reprogramming in oat grains and leaves. Notably, endogenous DGAT, WRI1 and OLEOSIN genes experienced upregulation, while genes associated with fatty acid biosynthesis, such as KASII, SACPD and FAD2, displayed antagonistic expression patterns between oat grains and leaves. Transcriptomic analyses highlighted significant differential gene expression, particularly enriched in lipid metabolism. Comparing the transgenic oat plants with the wild type, we observed a remarkable increase of up to 34% in oleic acid content in oat grains. Furthermore, there were marked improvements in the total oil content in oat leaves, as well as primary metabolites changes in both oat grains and leaves, while maintaining homeostasis in the transgenic oat plants. These findings underscore the effectiveness of genetic engineering in manipulating oat oil composition and content, offering promising implications for human consumption and animal feeding through oat crop improvement programmes.

Transposable elements: multifunctional players in the plant genome

Transposable elements (TEs) are indispensable components of eukaryotic genomes that play diverse roles in gene regulation, recombination, and environmental adaptation. Their ability to mobilize within the genome leads to gene expression and DNA structure changes. TEs serve as valuable markers for genetic and evolutionary studies and facilitate genetic mapping and phylogenetic analysis. They also provide insight into how organisms adapt to a changing environment by promoting gene rearrangements that lead to new gene combinations. These repetitive sequences significantly impact genome structure, function and evolution. This review takes a comprehensive look at TEs and their applications in biotechnology, particularly in the context of plant biology, where they are now considered "genomic gold" due to their extensive functionalities. The article addresses various aspects of TEs in plant development, including their structure, epigenetic regulation, evolutionary patterns, and their use in gene editing and plant molecular markers. The goal is to systematically understand TEs and shed light on their diverse roles in plant biology.

Highly Efficient and Reproducible Genetic Transformation in Pea for Targeted Trait Improvement

A reproducible tissue culture protocol is required to establish an efficient genetic transformation system in highly recalcitrant pea genotypes. High-quality callus with superior regeneration ability was induced and regenerated on optimized media enriched with copper sulfate and cytokinins, 6-benzylaminopurine and indole-3-acetic acid. This successful regeneration effort led to the development of a highly efficient transformation system for five pea genotypes using immature and mature seeds. The new transformation protocol included the addition of elevated glucose and sucrose concentrations for cocultivation and inoculation media to improve callus induction and regeneration, thus resulting in consistent transformation frequencies. Using the Agrobacterium strain AGL1, a transformation frequency of up to 47% was obtained for the pea genotype Greenfeast, using either of two different selection marker genes, PAT or NPT, sourced from two different vectors. Sixty-two transgenic pea events were able to survive kanamycin and phosphinothricin selection. A total of 30 transgenic events for Greenfeast, 15 for CN 43016, 9 for snap pea, and 5 for CN 31237 are reported herein. Two additional transgenic events were recovered from particle gun bombardment experiments. Quantitative RT-PCR analysis confirmed the transgenic status of pea plants, indicating elevated expression of relevant genes cloned into the transformation constructs.

Toward the development of Ac/Ds transposon-mediated gene tagging system for functional genomics in oat (Avena sativa L.)

Cultivated oat (Avena sativa L.) is an important cereal grown worldwide due to its multifunctional uses for animal feed and human food. Oat has lagged behind other cereals in the genetic and genomic studies attributed to its large and complex genomes. Transposon-based genome characterization has been utilized successfully for identifying and determining gene function in large genome cereals. To develop gene tagging and gene-editing resources for oat, maize Activator (Ac) and Dissociation (Ds) transposons were introduced into the oat genome using the biolistic delivery system. A total of 2035 oat calli were bombarded and twenty-four independent, stable transgenic events were obtained. Transformation frequencies were up to 19.0%, and 1.9% for bialaphos and hygromycin selection, respectively. Re-mobilization of the non-autonomous Ds element, by introducing Ac transposase source, led to a transposition frequency up to 16.8%. The properties of ten unique flanking sequences have been characterized to reveal the Ds-tagged sites in the oat genome. Genes at Ds insertion sites showed homology to gibberellin 20-oxidase 3, (1,3;1,4)-beta-D-glucan synthase, and aspartate kinase. This Ac/Ds transposon-based gene tagging system could facilitate and expedite functional genomic studies in oat.

Progress and challenges in sorghum biotechnology, a multipurpose feedstock for the bioeconomy

Sorghum [Sorghum bicolor (L.) Moench] is the fifth most important cereal crop globally by harvested area and production. Its drought and heat tolerance allow high yields with minimal input. It is a promising biomass crop for the production of biofuels and bioproducts. In addition, as an annual diploid with a relatively small genome compared with other C4 grasses, and excellent germplasm diversity, sorghum is an excellent research species for other C4 crops such as maize. As a result, an increasing number of researchers are looking to test the transferability of findings from other organisms such as Arabidopsis thaliana and Brachypodium distachyon to sorghum, as well as to engineer new biomass sorghum varieties. Here, we provide an overview of sorghum as a multipurpose feedstock crop which can support the growing bioeconomy, and as a monocot research model system. We review what makes sorghum such a successful crop and identify some key traits for future improvement. We assess recent progress in sorghum transformation and highlight how transformation limitations still restrict its widespread adoption. Finally, we summarize available sorghum genetic, genomic, and bioinformatics resources. This review is intended for researchers new to sorghum research, as well as those wishing to include non-food and forage applications in their research.