Control of pollen-mediated gene flow in transgenic trees.
Pollen elimination provides an effective containment method to reduce direct gene flow from transgenic trees to their wild relatives. Until now, only limited success has been achieved in controlling pollen production in trees. A pine (Pinus radiata) male cone-specific promoter, PrMC2, was used to drive modified barnase coding sequences (barnaseH102E, barnaseK27A, and barnaseE73G) in order to determine their effectiveness in pollen ablation. The expression cassette PrMC2-barnaseH102E was found to efficiently ablate pollen in tobacco (Nicotiana tabacum), pine, and Eucalyptus (spp.). Large-scale and multiple-year field tests demonstrated that complete prevention of pollen production was achieved in greater than 95% of independently transformed lines of pine and Eucalyptus (spp.) that contained the PrMC2-barnaseH102E expression cassette. A complete pollen control phenotype was achieved in transgenic lines and expressed stably over multiple years, multiple test locations, and when the PrMC2-barnaseH102E cassette was flanked by different genes. The PrMC2-barnaseH102E transgenic pine and Eucalyptus (spp.) trees grew similarly to control trees in all observed attributes except the pollenless phenotype. The ability to achieve the complete control of pollen production in field-grown trees is likely the result of a unique combination of three factors: the male cone/anther specificity of the PrMC2 promoter, the reduced RNase activity of barnaseH102E, and unique features associated with a polyploid tapetum. The field performance of the PrMC2-barnaseH102E in representative angiosperm and gymnosperm trees indicates that this gene can be used to mitigate pollen-mediated gene flow associated with large-scale deployment of transgenic trees.
ArborGen, Inc., Ridgeville, South Carolina 29472, USA.
Chunsheng
C
Zhang
Kim H
KH
Norris-Caneda
William H
WH
Rottmann
Jon E
JE
Gulledge
Shujun
S
Chang
Brian Yow-Hui
BY
Kwan
Anita M
AM
Thomas
Lydia C
LC
Mandel
Ronald T
RT
Kothera
Aditi D
AD
Victor
Leslie
L
Pearson
Maud A W
MA
Hinchee
D001426:Bacterial Proteins; D005052:Eucalyptus / Q000235:genetics / Q000254:growth & development; D018628:Gene Dosage / Q000235:genetics; D051456:Gene Flow / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D005966:Glucuronidase / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D028223:Pinus / Q000166:cytology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D011058:Pollen / Q000166:cytology / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012038:Regeneration; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D014197:Trees / Q000235:genetics* / Q000254:growth & development
D001426:Bacterial Proteins; D050505:Mutant Proteins; D010940:Plant Proteins; D012260:Ribonucleases; C019760:Bacillus amyloliquefaciens ribonuclease; D005966:Glucuronidase