Generation of transgenic maize with enhanced provitamin A content.
Vitamin A deficiency (VAD) affects over 250 million people worldwide and is one of the most prevalent nutritional deficiencies in developing countries, resulting in significant socio-economic losses. Provitamin A carotenoids such as beta-carotene, are derived from plant foods and are a major source of vitamin A for the majority of the world's population. Several years of intense research has resulted in the production of 'Golden Rice 2' which contains sufficiently high levels of provitamin A carotenoids to combat VAD. In this report, the focus is on the generation of transgenic maize with enhanced provitamin A content in their kernels. Overexpression of the bacterial genes crtB (for phytoene synthase) and crtI (for the four desaturation steps of the carotenoid pathway catalysed by phytoene desaturase and zeta-carotene desaturase in plants), under the control of a 'super gamma-zein promoter' for endosperm-specific expression, resulted in an increase of total carotenoids of up to 34-fold with a preferential accumulation of beta-carotene in the maize endosperm. The levels attained approach those estimated to have a significant impact on the nutritional status of target populations in developing countries. The high beta-carotene trait was found to be reproducible over at least four generations. Gene expression analyses suggest that increased accumulation of beta-carotene is due to an up-regulation of the endogenous lycopene beta-cylase. These experiments set the stage for the design of transgenic approaches to generate provitamin A-rich maize that will help alleviate VAD.
Aluru
Maneesha
M
Department of Genetics, Development and Cell Biology, 253 Bessey Hall, Iowa State University, Ames, IA 50011, USA.
Xu
Yang
Y
Guo
Rong
R
Wang
Zhenguo
Z
Li
Shanshan
S
White
Wendy
W
Wang
Kan
K
Rodermel
Steve
S
D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004885:Erwinia / Q000201:enzymology; D005818:Genetic Engineering; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism*; D019207:beta Carotene / Q000096:biosynthesis* / Q000235:genetics
D001426:Bacterial Proteins; D019207:beta Carotene; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase