Cannabis (Cannabis sativa L.) is a dioecious plant cultivated worldwide for thousands of years. Besides the narcotic and therapeutic effects, Cannabis can be used as raw materials in multiple fields, including bioenergy, textiles, food, and ecological restoration. It is also an efficient bioremediation agent for contaminated soil, as well as greenhouse gas absorption. With the expansion of the market, there has been an increased demand to develop Cannabis cultivars with enhanced traits. As a major science breakthrough, the advent of the CRISPR/Cas system will revolutionize the basic and applied research in Cannabis. This article provides an overview of the recent advances in the optimization of a transformation system and in the gene editing of Cannabis. To achieve the full potential of this environmentally friendly and sustainable crop, we highlight future directions of genetic modification as well as several bottlenecks to overcome.

Female inflorescence is the primary output of medical Cannabis. It contains hundreds of cannabinoids that accumulate in the glandular trichomes. However, little is known about the genetic mechanisms governing Cannabis inflorescence development. In this study, we reported the map-based cloning of a gene determining the number of inflorescences per branch. We named this gene CsMIKC1 since it encodes a transcription factor that belongs to the MIKC-type MADS subfamily. Constitutive overexpression of CsMIKC1 increases inflorescence number per branch, thereby promoting flower production as well as grain yield in transgenic Cannabis plants. We further identified a plant-specific transcription factor, CsBPC2, promoting the expression of CsMIKC1. CsBPC2 mutants and CsMIKC1 mutants were successfully created using the CRISPR-Cas9 system; they exhibited similar inflorescence degeneration and grain reduction. We also validated the interaction of CsMIKC1 with CsVIP3, which suppressed expression of four inflorescence development-related genes in Cannabis. Our findings establish important roles for CsMIKC1 in Cannabis, which could represent a previously unrecognized mechanism of inflorescence development regulated by ethylene.