Introduction
In the ever-evolving world of cannabis cultivation, breakthroughs in research and understanding are paramount to optimizing practices, reducing environmental impacts, and maximizing yields. This article, co-authored by Jorge Cervantes and Dr. Gary Yates, delves into a discovery by a team at Aurora, a Canadian Licensed Producer. The team's research has unveiled a naturally occurring mutation that potentially explains the varying flowering times of cannabis plants. This revelation could revolutionize the way growers and breeders approach cannabis cultivation, offering a potential reduction in environmental impacts and production costs in the cannabis industry.
Jorge Cervantes, with his 40 years of experience in the field of cannabis cultivation, brings to this article a wealth of knowledge and expertise. His emphasis on understanding the scientific principles and fundamentals of cannabis cultivation is evident throughout the piece. Cervantes' commitment to organic growing practices, sustainable and responsible cultivation, and fostering a community of informed growers shines through, reflecting his vast body of work, including "The Cannabis Encyclopedia." With his solid academic background in Genetics and Plant Science, Dr. Gary Yates complements Cervantes' insights by adding scientific explanations and fundamentals. Dr. Yates' dedication to understanding the unique biological and medicinal properties of the cannabis plant, combined with his commercial acumen, brings a fresh perspective to the article. His work at PharmaSeeds and extensive academic achievements, including a BSc (Hons) in Molecular Genetics and a Ph.D. focused on plant stress, further establish his authority in the field.
Article - Aurora Study on Autoflowering Genes
Hola, amigos! Jorge Cervantes and Dr. Gary Yates here, and today, we will delve into some exciting research that could revolutionize cannabis cultivation and breeding.
A team at Aurora, a global cannabis licensed producer, has made a breakthrough in understanding the flowering times of cannabis plants. They've discovered a mutation that likely explains why some cannabis plants have different flowering times. This could be a game-changer for growers and breeders, allowing us to manipulate flowering time, potentially reducing environmental impacts and production costs in the cannabis industry.
Photoperiod Plants
Most photoperiod cannabis cultivars initiate flowering when the amount of light they receive is reduced from ‘long days’ down to ‘short days’. This process is referred to as “triggering,” or flowering initiation, and cultivars that respond to this change in day length are called photoperiod sensitive or light dependent. This type of flowering works well for growing in indoor and greenhouse facilities where growers can control the duration/number of hours of light per day. However, it's not so great for outdoor cultivation in northern latitudes, like in Canada, where Aurora is based. The shortened day length required to initiate flowering doesn't occur until August, pushing harvest to October, when the risk of frost and pathogen damage increases significantly
Autoflowering Plants
Autoflowering varieties that flower regardless of day length have an advantage in more northern climates. Autoflowering cultivars flower at a determined number of weeks after germination, so growers can control flowering time by selecting when they sow the seeds. This allows for cultivation outdoors with a much lower environmental impact and in a much wider range of latitudes, including Canada. However, autoflowering cultivars historically have lower yields and cannabinoid concentrations than photoperiod-sensitive cultivars.
Same Gene, Different Expression
The team found 2,826 genes were differentially expressed between autoflowering and photoperiod-dependent varieties during vegetative growth. However, a few potential natural mutations controlled the expression of many of these.
The Aurora team proposes that a malfunctioning gene in the circadian clock of cannabis is responsible for the unusual yet more predictable flowering time of auto-flowering cultivars. They narrowed their search to two possible genes (APS2 and PRR37), and it became clear that the loss of a ‘flowering time’ repressor is the functional component in this pathway, an example of negative regulation.
Circadian Clocks
All organisms contain internal clocks (circadian rhythm) that help them time biological events to specific times of the day, year, or life cycle. In plants, the circadian clock helps integrate changes in day length with developmental processes such as flowering. The Aurora team characterized a natural single-point mutation in PRR37, a gene that plays a central role in the plant’s circadian clock. The mutation causes splicing variants in the resulting protein; these splice variants make a shorter, truncated protein, which replaces the full-length PRR37 protein, resulting in early flowering.
Splicing
One of the levels of regulation involved in gene expression is RNA processing. The initial RNA transcript produced from DNA in the nucleus is called pre-mRNA. This pre-mRNA consists of both coding regions and non-coding regions. The coding regions are called "exons," and the non-coding regions are called "introns." In a eukaryotic cell, like plants and humans have, the introns need to be removed and the exons joined together to form a mature mRNA molecule that can be translated into a protein. This process of cutting and joining is known as RNA splicing. The mutation here causes an alternative splice variant, which triggers early flowering through the formation of a truncated PRR37 protein.
This knowledge of the precise mutation that causes autoflowering in cannabis allows for fast-track breeding of elite-quality autoflowering cultivars that can be grown commercially outdoors. This gives growers more options and uses fewer resources to grow cannabis.
How They Did It
The study used RNA sequencing to analyze gene expression differences between photoperiod-sensitive and auto-flowering genotypes during vegetative growth. The results showed significant differential expression of genes, including those with sequence homology to known Arabidopsis floral regulators (Arabidopsis thaliana is a model plant and the most studied and understood plant on earth). The study also examined mRNA expression levels throughout development in autoflowering and photoperiod genotypes, showing massive differences. However, the expression of the photoperiod-dependent plants during flowering and the autoflowering plants during vegetation was similar. All in all, the evidence points to a very likely mechanism for controlling autoflowering.
In summary, this research is a big step in our understanding of cannabis cultivation. We can optimize cultivation practices, reduce environmental impacts, and increase yields by manipulating the flowering time. It's an exciting time to be a cannabis grower or breeder!
As always, stay curious and keep growing, amigos!
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References
Research May Explain Gene Responsible for Autoflowering Cannabis: https://www.cannabisbusinesstimes.com/news/autoflowering-cannabis-research-aurora-occo/?trk=public_post-text
Study - Loss of daylength sensitivity by splice site mutation in Cannabis:
https://www.biorxiv.org/content/10.1101/2023.03.10.532103v1.full.pdf
