Epigenetics: Environmental Influence on Phenotypic Expression

Epigenetics refers to heritable changes in gene expression that do not involve alterations to the underlying DNA sequence. In Cannabis sativa, epigenetic mechanisms, primarily DNA methylation and histone modification, play a crucial role in how a cultivar responds to its environment.

When a clone is placed in an environment with high UV-B radiation or significant temperature fluctuations, it can express greatly different cannabinoid ratios and anthocyanin (purple pigmentation) production compared to its genetic identical grown in standard conditions. This phenotypic plasticity allows the plant to adapt to abiotic stress. Research indicates that these stress-induced epigenetic markers can sometimes be passed down to the next generation, a vital consideration for breeders stabilizing traits in diverse climates.

The implications of these epigenetic shifts are major for commercial cultivation. A phenomenon known as 'clonal degradation' or 'phenotypic drift' can occur when mother plants are kept in suboptimal conditions for extended periods. Over time, the accumulation of stress-induced DNA methylation can cause the clones to slowly lose their vigor and original terpene profiles, necessitating the use of tissue culture to strip these epigenetic markers and restore the cultivar to its true genetic baseline.