The effects of time, temperature and plant variety on pollen viability and its implications for gene flow risk.

Abstract

Pollen viability affects the probability that a pollen grain deposited on a plant's stigma will produce a viable seed. Because a mature seed is needed before a gene flow event can occur, pollen viability will influence the risk of escape for genetically engineered (GE) crops. Pollen viability was measured at intervals for up to 2h following removal of the pollen from the anthers. It was quantified at three temperatures and for different alfalfa varieties, including both conventional and Roundup Ready (RR) varieties. Pollen viability was assessed using invitro germination. Time since removal from the anthers was the most prevalent factor affecting pollen viability in alfalfa. Pollen viability declined with increasing time at all three temperatures and for all varieties tested. Pollen viability was not affected by temperatures ranging between 25 and 37°C and did not vary among plant varieties, including conventional and RR varieties. Bee foraging behaviour suggested pollen viability within the first 10min following pollen removal from a flower to most affect seed production. Pollen longevity was predicted to have little impact on seed set and gene flow. Linking pollinator behaviour to pollen viability improved our understanding of its impact on gene flow risk.