Is Vrn3 a Good Candidate Gene for Vernalization Control of Flowering in Lolium?.

The contamination of turf type perennial ryegrass seed lots by annual ryegrass through physical seed mixing or gene flow can significantly reduce turfgrass quality.  One of the characteristics that can be used to differentiate annual from perennial ryegrass is the flowering habit of these two species.  Perennial ryegrass requires a period of cold temperatures and short days (vernalization) followed by a photoperiod over 14 hours before flowering will be initiated, however, annual ryegrass typically does not have these requirements.  Genetic markers from regions of the ryegrass genome that influence the control of flowering have the potential to be useful by seed certification agencies for quality control.  Controlled environment studies were conducted to phenotype the progeny from an annual (Lolium multiflorum) x perennial (Lolium perenne) ryegrass mapping population for days to flowering under 8, 16 and 24-hour photoperiods with and without vernalization.  One QTL influencing photoperiodic control of flowering time was identified and mapped to Lolium linkage group 4.  A second QTL influencing vernalization control of flowering was identified and mapped to Lolium linkage group 7.   One candidate gene (Vrn3) that influences vernalization control of flowering in other grass species maps near the vernilization QTL on Lolium linkage group 7 and could prove to be a useful marker for ryegrass species separation.