Maize Pollen Longevity and Distance Isolation Requirements for Effective Pollen Control

Abstract

Pollen is an important vector of gene flow in maize (Zea mays L.). Experiments were conducted to investigate the duration of pollen viability and the effectiveness of isolation distance for controlling gene flow. Pollen longevity was tested by collecting pollen at dehiscence and exposing it in a thin layer in the open air and sunshine for prescribed time periods before assessing pollen viability by measuring seed set after pollination and scoring visual appearance. Isolation distance efficacy was evaluated by growing 12.8‐m2 plot of maize at various distances from a 4000‐m2 pollen source. The pollinator contained either a genetic leaf or seed marker that allowed pollen flow to be measured. Pollen maintained viability for 1 to 2 h after dehiscence depending on atmospheric water potential. The theoretical, maximum distance viable pollen could move was 32 km, assuming pollen was transported linearly at the maximum average afternoon windspeeds for our location, viability was maintained for 2 h, and pollen settling rate was ignored. Cross pollinations occurred at a maximum distance of 200 m from the source planting, and only a limited number of cross pollinations occurred at the shortest distance (100 m). No cross pollinations occurred at 300 m from the source planting. The results are consistent with conclusions that maize pollen is desiccation intolerant and has a high settling rate. The results indicate isolation distance can be a useful tool for controlling gene flow via pollination in research scale plantings.

Cross-fertilization between genetically modified and non-genetically modified maize crops in Uruguay

“…Despite limitations due to variations in an array of factors, sampling commercial field situations may estimate conditions in which cross-fertilization occurs better than experimental designs. For instance, maize plots have been established to be evaluated as recipients of pollen at regular distances from a pollen source plot (Luna et al, 2001). Results obtained following this approach may not be representative of commercial situations in which recipient and sources are of much greater size.…”

“…Maize pollen grains are viable for one or two hours after emerging from the cob (Luna et al, 2001). However, pollen can often remain viable for more than 24 hours, a period that depends on temperature, humidity and atmospheric water potential (Ma et al, 2004).…”

Responses of spikelet fertility to air, spikelet, and panicle temperatures and vapor pressure deficit in rice

“…Luna et al (2001) reported that pollen viability was related with exposed time in the drying conditions and pollen death was due mainly to dehydration. Aylor et al (2003) reported that depending on the VPD, the water contents of maize pollen could change from being fully hydrated to being nearly dehydrated in 1-4 hour.…”

Pollen-mediated gene flow from transgenic safflower (CarthamustinctoriusL.) intended for plant molecular farming to conventional safflower

“…Various factors affect outcrossing among plant populations: pollinator effects including pollinator species and distance to other pollen sources; spatial and abiotic factors including distance to compatible crops, humidity, wind direction and velocity, geographic and vegetative barriers; crop species effects including the number and diversity of plant species attractive to pollinators in the area, ploidy level of the populations, shape, size and density of pollen donor and receptor plant populations, floral synchrony, floral and inflorescence position on the plant, pollen longevity, and cross-compatibility. Many of these factors interact, making predictions difficult without empirical measurements (Hoyle et al, 2007;Luna et al, 2001;Messeguer, 2003;Rognli et al, 2000). While complete confinement of pollen and seed is not possible for any crop species to date (Levin and Kerster, 1974), management that incorporates spatial, temporal or vegetative barriers could minimize pollen-mediated gene flow between crops.…”