Loss of daylength sensitivity by splice site mutation in Cannabis pseudo‐response regulator

Abstract

SUMMARYPhotoperiod insensitivity (auto‐flowering) in drug‐type Cannabis sativa circumvents the need for short day (SD) flowering requirements making outdoor cultivation in high latitudes possible. However, the benefits of photoperiod insensitivity are counterbalanced by low cannabinoid content and poor flower quality in auto‐flowering genotypes. Despite recent studies in cannabis flowering, a mechanistic understanding of photoperiod insensitivity is still lacking. We used a combination of genome‐wide association study and genetic fine‐mapping to identify the genetic cause of auto‐flowering in cannabis. We then used gene expression analyses and transient transformation assays to characterize flowering time control. Herein, we identify a splice site mutation within circadian clock gene PSEUDO‐RESPONSE REGULATOR 37 (CsPRR37) in auto‐flowering cannabis. We show that CsPRR37 represses FT expression and its circadian oscillations transition to a less repressive state during SD as compared to long days (LD). We identify several key circadian clock genes whose expression is altered in auto‐flowering cannabis, particularly under non‐inductive LD. Research into the pervasiveness of this mutation and others affecting flowering time will help elucidate cannabis domestication history and advance cannabis breeding toward a more sustainable outdoor cultivation system.

A FLOWERING LOCUS T ortholog is associated with photoperiod‐insensitive flowering in hemp (Cannabis sativa L.)

“…Two recent mapping studies have suggested C. sativa homologues of APETALA2 and PSEUDO-RESPONSE REGU-LATOR 37 (PRR37) as candidate genes within Autoflower1 (Garfinkel et al, 2023;Leckie et al, 2023). Alterations of PRR37 homologues in T. aestivum, O. sativa, and Sorghum bicolor are known to confer photoperiod insensitivity due to de-repressed FT expression (Beales et al, 2007;Koo et al, 2013;Murphy et al, 2011).…”