Exploring Ethylene-Related Genes inCannabis sativa: Implications for Sexual Plasticity

Abstract

Sexual plasticity describes an organism's ability to change its phenotypic sex in response to environmental, chemical or physiological cues without a change in sex chromosome karyotype. Cannabis sativa L. (cannabis) is a medically important dioecious crop, with a pair of heteromorphic XY sex chromosomes. Cannabis has demonstrated sexual plasticity in response to chemical treatments which target the biosynthesis and signalling of ethylene. To date, ethylene biosynthesis and signalling has not been specifically studied in C. sativa, and the role of ethylene-related genes (ERGs) in sexual plasticity in the species has not been investigated. In the present study, we performed gene orthology analysis based on the model species Arabidopsis thaliana L. to reconstruct the C. sativa Yang Cycle, ethylene biosynthesis and ethylene signalling pathways, whose canonical composition appear conserved in cannabis. Additionally, we employ two transcriptomic datasets containing male, female and chemically induced male flowers to investigate patterns of expression for ethylene-related genes which may be involved in sexual plasticity. Comparison of these transcriptomes highlighted CsERGs whose differential expression was associated with sexual determination and those which we propose are associated with the sexual plasticity. These sexual plasticity ERGs could be classified into two patterns of expression: karyotype concordant (KC) and unique (uERG). We show that CsERGs involved in sexual plasticity are distributed throughout the genome and are not exclusive to the sex chromosomes, suggesting a broad control of sexual plasticity in C. sativa.

Comprehensive Phenotypic Characterization of Diverse Drug-Type Cannabis Varieties from the Canadian Legal Market

“…Feminized seeds and regular seeds are two types of cannabis seeds that differ primarily in their genetic makeup and reproductive characteristics [8]. Regular seeds are of high importance for breeders and growers to develop new varieties.…”

“…Regular seeds exhibit a roughly 25% likelihood of producing male plants, which can pose challenges as non-fertilized female plants are preferred due to their higher cannabinoid production. In contrast, cannabis's flexible sexuality has led to the development of an intelligent approach to masculinize female plants, using foliar sprays of specific plant growth regulators or inhibitors (e.g., silver thiosulfate) [8], to produce female seeds, so-called feminized seeds. Significant differences between the plants derived from regular female seeds and feminized seeds were found in this study.…”

“…Generally, it is dioecious (2n = 20), characterized by nine autosomes and one pair of sex chromosomes. However, the process of sex determination in cannabis is rather intricate; most drug-type cannabis plants are dioecious, exclusively producing either male (XY) or female (XX) flowers [7][8][9]. On the other hand, some plants, primarily hemp, exhibit monoecious characteristics, with both male and female flowers growing on the same plant [10].…”

“…Under specific conditions, dioecious plants may revert to a monoecious-like state, known as hermaphroditism [7,11,12]. In cannabis, sex holds a great importance: unpollinated female flowers produce and store considerably more cannabinoids than male flowers [7,8,13].…”