Pollen-mediated gene flow in wheat at the commercial scale

Currently, information is lacking on gene flow in common wheat (Triticum aestivum L.) at distances greater than 300 m based on commercial-scale fields. The objective of this research was to measure pollen-mediated gene flow rates from a blue-aleuroned pollinator (T aestivum cv. 'Purendo-38') to neighboring commercial fields of common wheat grown within a 10-km radius of a central pollinator field. In the 2-yr study, 33-ha (2002) and 20-ha (2003) fields of Purendo-38 were sown 200 km east-northeast of Saskatoon, Saskatchewan. Sixty-nine fields in 2002 and 76 fields in 2003 were identified as having overlapping flowering relative to Purendo-38. At maturity, up to 2 m(2) samples were harvested from each corner of each recipient field. Gene flow was identified by the expression of a light-blue pigment in the aleurone layer of F-1 hybrid seed. In 2002 one case of gene flow was confirmed at 190 m northeast of the pollinator at a rate of 0.01%. In 2003 nine putative hybrid seeds were confirmed to be the result of gene flow between Purendo-38 and the recipient field using gliadin fingerprinting. Consequently, gene flow was confirmed at 0.01% at 500 m northeast, 630 m southeast, and 2.75 km northwest from the pollinator. In commercial production, gene flow in wheat occurs at trace levels (<= 0.01%) at distances up to 2.75 km.