Over-expression of AGPase genes enhances seed weight and starch content in transgenic maize |
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Authors: | Ning Li Shujuan Zhang Yajie Zhao Bei Li Juren Zhang |
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Institution: | (1) School of Life Science, Shandong University, 27 Shanda South Road, Jinan, 250100, People’s Republic of China; |
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Abstract: | Cereal crops accumulate starch in the seed endosperm as an energy reserve. ADP-glucose pyrophosphorylase (AGPase) plays a
key role in regulating starch biosynthesis in cereal seeds. The AGPase in the maize endosperm is a heterotetramer of two small
subunits, encoded by Brittle2 (Bt2) gene, and two large subunits, encoded by the Shrunken2 (Sh2) gene. The two genes (Bt2, Sh2) from maize were introduced into two elite maize inbred lines, solely and in tandem, and under the control of endosperm-specific
promoters for over-expression. PCR, Southern blotting, and real-time RT-PCR analysis indicated that the transgenes were integrated
into the genome of transgenic plants and were over-expressed in their progeny. The over-expression of either gene enhanced
AGPase activity, seed weight and starch content compared with the WT, but the amounts were lower than plants with over-expression
of both Bt2 and Sh2. Developing seeds from co-expression transgenic maize plants had higher cytoplasmic AGPase activity: the 100-grain weight
increased 15% over the wild type (WT), and the starch content increased to over 74% compared with the WT of 65%. These results
indicate that over-expression of the genes in transgenic maize plants could improve kernel traits. This report provides a
feasible approach for increasing starch content and seed weight in maize. |
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