Pollen flow in wheat revisited

100 %
0 %
Information about Pollen flow in wheat revisited
News-Reports

Published on October 4, 2007

Author: Megane

Source: authorstream.com

Pollen Flow in Wheat Revisited:  Pollen Flow in Wheat Revisited Joel Ransom Extension Agronomist – Cereal Crops Why renewed interest in pollen flow in wheat?:  Why renewed interest in pollen flow in wheat? Steady progress in the development of wheat with transgenic traits Certain markets have indicated that they require non-transgenic wheat Pollen drift is one of many factors to consider when maintaining segregation Information on out-crossing in wheat can help design effective identity preserved (IP) programs How does gene flow via pollen drift occur?:  How does gene flow via pollen drift occur? Some biology: Pollen is produced in anthers Fertilization requires viable pollen to attach to a receptive stigma and the successful transfer to genetic material to the ovule. Facts about wheat pollen:  Facts about wheat pollen Relatively heavy Viable for 2 to 20 minutes 2,000 to 4,000 pollen grains per flower Factors affecting gene flow via pollen:  Factors affecting gene flow via pollen Distance between plants Temperature Humidity Wind Insects Variety Receptivity of the stigma ‘Nick’ (synchrony of flowering) Pollen viability Gene Flow via pollen in Wheat – Current State of Knowledge:  Gene Flow via pollen in Wheat – Current State of Knowledge Review of pollen movement studies Review of information from out-crossing studies Isolation distances Varietal effects How far can wheat pollen move?:  How far can wheat pollen move? Adapted from Khan et al, 1973 (Kansas) Pollination of a male sterile :  Pollination of a male sterile Adapted from Khan et al, 1973 Summary on pollen movement:  Summary on pollen movement Viable wheat pollen can move > 150 ft Based on male sterile plants, cross pollination risk greatest in first 20 ft of isolation from source Fertilization success dependant on pollen concentration Effect of variety and year on out-crossing in adjacent plants in Kansas, HRWW:  Effect of variety and year on out-crossing in adjacent plants in Kansas, HRWW Adapted from Martin, 1990 Effect of variety and year on out-crossing (92-93), HRSW, Canada:  Effect of variety and year on out-crossing (92-93), HRSW, Canada Adapted from Hucl, 1996 Effect of isolation distance on out-crossing of four Canadian wheat cultivars, 1995 :  Effect of isolation distance on out-crossing of four Canadian wheat cultivars, 1995 Adapted from Hucl & Matus-Cadiz, 2001 Slide13:  Source: Ostby et al., 2004 Factors conferring varietal differences in cross-pollination propensity:  Factors conferring varietal differences in cross-pollination propensity Glume opening Extrusion of anthers Duration of opening Open spikelets vs dense spikes What are the practical implications of these data?:  What are the practical implications of these data? Environment and variety can influence level of OC In the two studies with spring wheat summarized a distance > 33-59 ft sufficient gave zero outcrossing in HRSW Isolation distance >90: high probability of zero or minimal out-crossing What are typical isolation distances in “IP” systems in ND currently?:  What are typical isolation distances in “IP” systems in ND currently? Methodology Fields (within/between farms) sampled 8 Organic fields 8 certified/foundation seed production fields 3 IP fields Distance between closest wheat crop measured (all edges and corners) Distance of natural isolation distance measured Results:  Results Organic production fields (isolation required from non-organic fields - ? distance) Natural isolation Minimum distance – 0 ft Maximum – 250 ft Average – 57 ft Median – 45 ft Actual Minimum distance - 48 Maximum – 21,120 Average - 2640 Median - 2640 Results:  Results Certified Seed Production (current regulations – 5 ft) Natural isolation Minimum distance – 0 ft Maximum – 165 ft Average – 43 ft Median – 42 ft Actual Minimum distance - 5 Maximum – 21,120 Average – 4,933 Median – 2,640 Results:  Results Identity Preserved (isolation specified in contract) Natural isolation Minimum distance – 0 ft Maximum – 500 ft Average – 97 ft Median – 50 ft Actual Minimum distance – 1 ft Maximum – 15,840 ft Average – 2,039 ft Median – 152 ft Summary on isolation distances:  Summary on isolation distances Natural boundaries typically 50+ feet “Fields” are not always separated by natural boundaries If new standards of OC established for non-transgenic wheat requiring greater isolation (i.e. 60-90 ft): Most but not all IP fields currently close to these distances Seed production would be most impacted Conclusions:  Conclusions With an isolation distance of 60 - 90 ft (conservative based on the most promiscuous cultivar) there is limited risk of gene flow via pollen between cultivars of HRSW Zero tolerance cannot be guaranteed with this distance, however, as pollen is capable of much farther movement Current IP systems frequently have isolation distances approaching 60 ft, but sometimes much less Natural boundaries alone for isolation is not workable due to layout of fields Conclusions:  Conclusions Revised isolation distances in IP would likely not be too difficult to achieve Isolation distances in seed production would need to be revised to ensure increased purity Given limited out-crossing and current field layouts, gene flow from transgenic wheat to non-transgenic wheat will likely be minimal and manageable. Other factors in segregation process will present greater challenges?

Add a comment

Related presentations

Related pages

PPT - Pollen Flow in Wheat Revisited PowerPoint ...

Pollen Flow in Wheat Revisited. Joel Ransom Extension Agronomist – Cereal Crops. Why renewed interest in pollen flow in wheat?. Steady progress in the ...
Read more

Pollen Flow in Wheat Revisited Joel Ransom Extension ...

2 Why renewed interest in pollen flow in wheat? Steady progress in the development of wheat with transgenic traits Steady progress in the development of ...
Read more

Pollen flow in wheat revisited - Ace Recommendation ...

Why renewed interest in pollen flow in wheat? Steady progress in the development of wheat with transgenic traits Certain markets have indicated that they ...
Read more

Pollen Flow in Wheat Revisited Joel Ransom Extension ...

Download Pollen Flow in Wheat Revisited Joel Ransom Extension Agronomist – Cereal Crops.
Read more

Pollen flow in wheat revisited - Ace Recommendation ...

How does gene flow via pollen drift occur? Some biology:– Pollen is produced in anthers– Fertilization requires viable pollen to attach to a receptive ...
Read more

PPT – Pollen Flow in Wheat Revisited PowerPoint ...

Fertilization requires viable pollen to attach to a receptive ... Pollen viability. Gene Flow via pollen in Wheat Current State ... Viable wheat pollen can ...
Read more

Pollen flow in wheat revisited - Ace Recommendation ...

Pollen Flow in Wheat RevisitedJoel RansomExtension Agronomist – Cereal Crops
Read more

NDSU Extension Service Biotechnology Resources - Presentations

Crop Biotechnology Update Conference Presentations ... Pollen Flow in Wheat Revisited ... Gene Flow Through Pollen Drift in Wheat: ...
Read more

PPT - Gene Flow Through Pollen Drift: A Scientific ...

Gene Flow Through Pollen Drift: A Scientific Perspective. ... Gene flow through pollen drift is low in wheat and IP ... Pollen Flow in Wheat Revisited ...
Read more

Gene Flow Through Pollen Drift: A Scientific Perspective ...

Gene Flow Through Pollen Drift: A Scientific Perspective Joel Ransom Extension Agronomist – Cereal Crops. ... (i.e. wheat and jointed goatgrass).
Read more