Transgenic maize plants expressing a fungal phytase gene
Transgenic maize plants expressing a fungal phytase gene
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DOI：
10.1007/s11248-007-9138-3
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发表时间：
2008-08-01
影响因子：
3
通讯作者：
Shi, Jinrui
中科院分区：
文献类型：
--
作者：
Chen, Rumei;Xue, Guangxing;Shi, Jinrui
玉米种子是商品猪和家禽饲料的主要成分。玉米种子中的磷主要以植酸盐的形式存在。单胃动物无法获得植酸磷，需要补充磷酸盐以达到最佳动物生长。动物粪便中未消化的植酸被认为是农业生产中对环境造成磷污染的主要来源。通过发酵产生的微生物植酸酶作为饲料添加剂被广泛用于管理由植酸引起的营养和环境问题，但这种方法与酶的生产成本和饲料加工和日粮配方中的特殊照顾要求有关。另一种方法是生产含有高植酸酶活性的植物种子。我们利用玉米胚特异性球蛋白-1启动子驱动的构建体在玉米种子中过表达黑曲霉phyA2基因。鉴定出具有简单整合模式的低拷贝数转基因株系。Western-blot分析显示，玉米中表达的植酸酶蛋白比酵母中表达的要小，这可能是由于糖基化程度不同造成的。转基因玉米种子的植酸酶活性达到每公斤种子约2,200单位，比非转基因玉米种子增加约50倍。植酸酶在4代间表达稳定。转基因种子正常发芽。研究结果表明，植酸酶表达系可用于培育新的玉米杂交种，以提高磷利用率，减少动物生产对环境的影响。
Maize seeds are the major ingredient of commercial pig and poultry feed. Phosphorus in maize seeds exists predominately 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.