Genome editing-CRISPR/Cas9 for the crop improvement of Industrial Cannabis sativa (Hemp)

Abstract

Industrial Cannabis sativa (Hemp) is a multipurpose revolutionary crop widely cultivated for its seeds, which are rich in oil, CBD content, proteins, carbohydrates, fibers, as well as vitamins and minerals. Genome editing, CRISPR/Cas9 acts as highly precise "genetic scissors" that accelerate traditional plant and animal breeding by modifying specific DNA sequences without introducing foreign (transgenic) DNA. The world's first genome-edited rice varieties are DRR Dhan 100 (Kamala) and Pusa DST Rice 1 developed by the Indian Council of Agricultural Research (ICAR),New Delhi, India. Genome editing, CRISPR/Cas9 revolutionizes Cannabis sativa (hemp) breeding by enabling precise, targeted modifications in a crop traditionally hampered by dioecy and high heterozygosity. CRISPR/Cas9 technology allows for sequence specific editing of the target genome, thereby allowing for precise control over gene modifications and associated traits, in a low cost and straightforward manner. Gene editing has been successfully used to generate climate-resilient crops for various climatic conditions. However, several limitations are descending its overall potential remains limited. The biological functions of most candidate genes are poorly characterized. For practical crop improvement in Cannabis sativa, functional validation serves as a bridge between genomic discovery and breeding applications. The Cannabis sativa genome has long been challenging to genetically manipulate due to recalcitrance in tissue culture and transformation, limiting functional validation of genes and targeted trait improvement. The major drawback of gene-editing technologies is off-target, which can cause unwanted editing of other genes, which hinders their wide applicability for crop trait improvement. Despite these advances, transformation and regeneration remain the major bottlenecks limiting widespread genome editing in Cannabis. Another disadvantage is the lack of efficient tissue culture methods for regeneration, transformation and regeneration of gene edited hemp crops. There are studies highlighting successful Cannabis sativa organogenesis but the commercial scale production is still a problem. However, in vitro regeneration of different varieties of hemp is very slow and found recalcitrant. This is another major disadvantage for the application of genome editing, CRISPR/Cas9 in the crop improvement of Industrial Cannabis sativa, hemp. Further limitations are caused by the regulatory uncertainty surrounding genetically edited cannabis.