Recently, researchers from North Carolina State University and the Beltsville Agricultural Research Center published the first review of research progress on genotype-independent plant transformation. In this review, researchers discussed recent advances in the use of regulatory genes in plant transformation and regeneration, as well as their potential to facilitate genotype-independent plant transformation and regeneration.
Somatic embryogenesis and de novo organogenesis are the two main means of plant regeneration. Many genetic and environmental factors can affect plant regeneration, and four types of regeneration-promoting factors play essential roles: wounding, epigenetic modifications, growth regulatory genes, and developmental regulatory genes. Wounding is the primary external trigger for callus induction from explants, which is caused by a series of damage-associated molecular patterns. These local wounding signals are translated into long-distance signals such as the electrical signal of GLUTAMATE RECEPTOR-LIKE cation channels, thereby inducing epigenetic modifications, alterations in the synthesis and accumulation of cytokinin and free auxin, and transcriptional upregulation of growth and developmental regulatory genes. Transcriptional changes include the activated expression of callus-inductive chromatin-remodeling regulator genes. These regeneration-promoting factors work together to tightly and precisely control each step of callus formation and plant regeneration.
How best to use plant developmental regulatory genes in plant transformation is a challenging question. Constitutive or ectopic expression of most such genes typically interferes with normal plant growth and development and causes undesirable pleiotropic effects. Fine-tuning the expression of these genes is critical for the regeneration of normal, fertile plants of different species. The researchers summarized the advantages and disadvantages of these regulatory factors and discussed the use of a dexamethasone (Dex)-inducible expression system or estradiol-inducible expression system to fine-tune their expression.
More information can be found in the review ‘Genotype-independent plant transformation’ published in the journal Horticulture Research.
Nathan A. Maren1,†, Hui Duan2,†,*, Kedong Da1, G. Craig Yencho1, Thomas G. Ranney3 and Wusheng Liu1,*
1 Department of Horticultural Science, North Carolina State University, Raleigh, NC, 27607, USA
2 USDA-ARS, U.S. National Arboretum, Floral and Nursery Plants Research Unit, Beltsville Agricultural Research Center (BARC)-West, Beltsville, MD 20705, USA
3 Mountain Crop Improvement Lab, Department of Horticultural Science, Mountain Horticultural Crops Research and Extension Center, North Carolina State University, Mills River, NC 28759, USA
About Dr. Wusheng Liu
Dr. Wusheng Liu is an assistant professor in Translational Genomics and Plant Bioengineering within the Department of Horticultural Science. The Liu laboratory is interested in:
i) development of novel approaches for non-GMO, genotype-independent delivery of the CRISPR/Cas9 system into crops for gene editing;
ii) understanding of the molecular mechanisms of agronomic traits, including seed size in Arabidopsis, soybean, and camelina, tomato fruit lycopene content, and potato internal heat necrosis;
iii) crop trait engineering using genetic engineering and gene editing such as modified flowering patterns in camelina and rose rosette virus resistance.
The Liu laboratory is also interested in computational tool–assisted de novo motif discovery and synthetic promoter engineering and in the use of plant synthetic biology for enhanced defense against nematodes in Arabidopsis and soybean.
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