An Efficient Intragenic Vector for Generating Intragenic and Cisgenic Plants in Citrus

Genetic transformation has become a promising tool for improvement of a variety of crop species. However, transferring genes across species, the presence of selectable marker genes, and bacteria-derived vector backbone sequences have raised considerable health and environmental concerns. Intragenic vector system-based intragenesis/cisgenesis is a new method using transgenic approach to achieving traditional breeding objectives but circumventing many of the associated shortcomings. We report here the development of an intragenic vector by assembling a T-DNA-like fragment and a buffering sequence following the left border from Citrus clementina into the backbone of the binary vector pCB302. Recovery of citrus regenerants is performed under non-selective conditions and positive intra-/cisgenic regenerants were identified through PCR analysis. Transformation efficiencies obtained in Arabidopsis and “Duncan” grapefruit were ~3% and ~0.67%, respectively, demonstrating the potential of the system for development of “foreign DNA-free” intra-/cisgenic citrus cultivars.

Regulation of gene-edited plants in Europe:from the valley of tears into the shining sun?

Some 20 years ago,the EU introduced complex regulatory rules for the growth of transgenic crops,which resulted in a de facto ban to grow these plants in fields within most European countries.With the rise of novel genome editing technologies,it has become possible to improve crops genetically in a directed way without the need for incorporation of foreign genes.Unfortunately,in 2018,the European Court of Justice ruled that such gene-edited plants are to be regulated like transgenic plants.Since then,European scientists and breeders have challenged this decision and requested a revision of this outdated law.Finally,after 5 years,the European Commission has now published a proposal on how,in the future,to regulate crops produced by new breeding technologies.The proposal tries to find a balance between the different interest groups in Europe.On one side,genetically modified plants,which cannot be discerned from their natural counterparts,will exclusively be used for food and feed and are-besides a registration step-not to be regulated at all.On the other side,plants expressing herbicide resistance are to be excluded from this regulation,a concession to the strong environmental associations and NGOs in Europe.Moreover,edited crops are to be excluded from organic farming to protect the business interests of the strong organic sector in Europe.Nevertheless,if this law passes European parliament and council,unchanged,it will present a big step forward toward establishing a more sustainable European agricultural system.Thus,it might soon be possible to develop and grow crops that are more adapted to global warming and whose cultivation will require lower amounts of pesticides.However,there is still a long way to go until the law is passed.Too often,the storm of arguments raised by the opponents,based on irrational fears of mutations and a naive understanding of nature,has fallen on fruitful ground in Europe.