Meeting Abstract
Many long-lived flowers have a diurnal pattern of opening and closing which determines how long they stay reproductively available during periods of pollinator activity. In the wild tomato clade (Solanum sect. Lycopersicum) there is variation in this floral behavior: flowers of ‘Awake’ species open before sunrise and close after sunset, while flowers of ‘Sleepy’ species open significantly later and close significantly earlier in the day. In this study, we 1) characterized the reproductive behavior of 10 species in the wild tomato clade as ‘Awake’ or ‘Sleepy,’ 2) assessed ecological variation among species to identify selective conditions associated with behavioral variation, and 3) examined the genetic basis of this trait using a recombinant F2 population segregating for this behavior. First, we found that floral opening and closing was a repeatable and diurnal behavior in a common garden across all four ‘Awake’ and six ‘Sleepy’ species. Second, using georeferenced climate data, we found that ‘Awake’ species tend to be at lower elevation and in environments that are more arid and experience more temperature variation, compared to ‘Sleepy’ species. Third, an F2 population was created from a cross between ‘Awake’ and ‘Sleepy’ parent species, and we screened both parents and F2s for allelic variation in known circadian clock genes. F2 segregation patterns indicate that behavioral variation is due to at least three loci. Patterns of association between circadian clock genotypes and floral phenotypes implicate PhytochromeA (a cytoplasmic photoreceptor) as one of these loci. This work broadens our understanding of how selective conditions could shape floral circadian rhythms, and the genetic underpinnings of such reproductive behaviors.
