title: Transgenic maize plants expressing a fungal phytase gene.
abstract: Maize seeds are the major ingredient of commercial pig and poultry feed. Phosphorus in maize seeds exists predominantly in the form of phytate. Phytate phosphorus is not available to monogastric animals and phosphate supplementation is required for optimal animal growth. Undigested phytate in animal manure is considered a major source of phosphorus pollution to the environment from agricultural production. Microbial phytase produced by fermentation as a feed additive is widely used to manage the nutritional and environmental problems caused by phytate, but the approach is associated with production costs for the enzyme and requirement of special cares in feed processing and diet formulation. An alternative approach would be to produce plant seeds that contain high phytase activities. We have over-expressed Aspergillus niger phyA2 gene in maize seeds using a construct driven by the maize embryo-specific globulin-1 promoter. Low-copy-number transgenic lines with simple integration patterns were identified. Western-blot analysis showed that the maize-expressed phytase protein was smaller than that expressed in yeast, apparently due to different glycosylation. Phytase activity in transgenic maize seeds reached approximately 2,200 units per kg seed, about a 50-fold increase compared to non-transgenic maize seeds. The phytase expression was stable across four generations. The transgenic seeds germinated normally. Our results show that the phytase expression lines can be used for development of new maize hybrids to improve phosphorus availability and reduce the impact of animal production on the environment.
authors.affiliation: Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P.R. China.
authors.forename: Rumei
authors.initials: R
authors.lastname: Chen
authors.forename: Guangxing
authors.initials: G
authors.lastname: Xue
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Yang
authors.forename: Qianli
authors.initials: Q
authors.lastname: Ma
authors.forename: Yunliu
authors.initials: Y
authors.lastname: Fan
authors.forename: Zuoyu
authors.initials: Z
authors.lastname: Zhao
authors.forename: Mitchell C
authors.initials: MC
authors.lastname: Tarczynski
authors.forename: Jinrui
authors.initials: J
authors.lastname: Shi
mesh_terms: D010832:6-Phytase / Q000235:genetics* / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics; D015153:Blotting, Western; D005916:Globulins / Q000235:genetics; D010758:Phosphorus / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012639:Seeds / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D005916:Globulins; D010758:Phosphorus; D010833:Phytic Acid; D010832:6-Phytase