Over-expression of AGPase genes enhances seed weight and starch content in transgenic maize
Over-expression of AGPase genes enhances seed weight and starch content in transgenic maize
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DOI：
10.1007/s00425-010-1296-5
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发表时间：
2011-02-01
期刊：
影响因子：
4.3
通讯作者：
Zhang, Juren
中科院分区：
文献类型：
--
作者：
Li, Ning;Zhang, Shujuan;Zhang, Juren
谷类作物在种子胚乳中积累淀粉作为能量储备。ADP-葡萄糖焦磷酸化酶（ADP-glucose pyrophosphorylase，AGP-P）在调节谷类种子淀粉合成中起着关键作用。玉米胚乳中的AGG是由Brittle 2（Bt 2）基因编码的两个小亚基和Shrunken 2（Sh 2）基因编码的两个大亚基组成的异源四聚体。将来自玉米的两个基因（Bt 2、Sh 2）单独和串联导入两个优良玉米自交系中，并在胚乳特异性启动子的控制下过量表达。PCR、Southern杂交和实时荧光定量RT-PCR分析表明，外源基因已整合到转基因植株的基因组中，并在后代中过量表达。与野生型相比，任一基因的过表达增强了AGR 1活性、种子重量和淀粉含量，但量低于Bt 2和Sh 2两者均过表达的植物。从共表达转基因玉米植株发育的种子具有更高的细胞质AGEs活性：百粒重比野生型（WT）增加15%，淀粉含量比野生型（WT）的65%增加到74%以上。这些结果表明，在转基因玉米植株中过量表达这些基因可以改善籽粒性状。本研究为提高玉米淀粉含量和粒重提供了一条可行的途径。
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.