California Cannabis Research Briefing, April 2023: Meeting Summary.

On April 28, 2023, the University of California Office of the President, in partnership with the California Department of Cannabis Control (DCC), hosted the California Cannabis Research Briefing. The California Cannabis Research Briefing brought together researchers and state agencies/policymakers to discuss pertinent policy issues on cannabis within the state. Researchers across six different topic areas (environment, cannabis markets, social equity matters, public health, medicinal cannabis use, and public safety) provided brief explanations of their research and its policy implications.

Sequence modification on demand: search and replace tools for precise gene editing in plants.

Until recently, our ability to generate allelic diversity in plants was limited to introduction of variants from domesticated and wild species by breeding via uncontrolled recombination or the use of chemical and physical mutagens-processes that are lengthy and costly or lack specificity, respectively. Gene editing provides a faster and more precise way to create new variation, although its application in plants has been dominated by the creation of short insertion and deletion mutations leading to loss of gene function, mostly due to the dependence of editing outcomes on DNA repair pathway choices intrinsic to higher eukaryotes. Other types of edits such as point mutations and precise and pre-designed targeted sequence insertions have rarely been implemented, despite providing means to modulate the expression of target genes or to engineer the function and stability of their protein products.

Genome Editing to Achieve the Crop Ideotype in Tomato.

For centuries, combining useful traits into a single tomato plant has been done by selective crossbreeding that resulted in hundreds of extant modern cultivars. However, crossbreeding is a labor-intensive process that requires between 5 and 7 years to develop a new variety. More recently, genome editing with the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system has been established as an efficient method to accelerate the breeding process by introducing targeted modifications to plant genomes via generation of targeted double-strand breaks (DSBs).

De novo domestication of wild tomato using genome editing.

Breeding of crops over millennia for yield and productivity has led to reduced genetic diversity. As a result, beneficial traits of wild species, such as disease resistance and stress tolerance, have been lost. We devised a CRISPR-Cas9 genome engineering strategy to combine agronomically desirable traits with useful traits present in wild lines.

Agrobacterium rhizogenes-mediated transformation of a dioecious plant model Silene latifolia.

Silene latifolia serves as a model species to study dioecy, the evolution of sex chromosomes, dosage compensation and sex-determination systems in plants. Currently, no protocol for genetic transformation is available for this species, mainly because S. latifolia is considered recalcitrant to in vitro regeneration and infection with Agrobacterium tumefaciens.