Transgenic barley grain overexpressing thioredoxin shows evidence that the starchy endosperm communicates with the embryo and the aleurone
Transgenic barley grain overexpressing thioredoxin shows evidence that the starchy endosperm communicates with the embryo and the aleurone
复制标题
DOI：
10.1073/pnas.212641999
复制
发表时间：
2002-11
影响因子：
11.1
通讯作者：
J. Wong;Yong-Bum Kim;P. Ren;Nick Cai;M. Cho;P. Hedden;P. Lemaux;B. Buchanan
中科院分区：
文献类型：
--
作者：
J. Wong;Yong-Bum Kim;P. Ren;Nick Cai;M. Cho;P. Hedden;P. Lemaux;B. Buchanan
在此之前，我们利用含有信号肽序列的B1-hordein启动子获得了高表达小麦硫氧还蛋白h转基因的大麦纯合子株系（高表达30倍），并发现其淀粉脱支酶（pullulanase）丰富。在这里，我们描述了生物化学活性，过表达硫氧还蛋白h对发芽和α-淀粉酶活性的影响。与缺乏转基因的零分离对照相比，过表达硫氧还蛋白h的纯合子(i) α-淀粉酶活性和发芽率加快，赤霉素A1 （GA1）含量增加1.6- 2.8倍；（ii）用赤霉素孵育的转基因脱胚籽粒α-淀粉酶活性也有类似的加速现象；（iii）丙醇可溶性蛋白（hordein I部分）的相对还原比（SH丰度）增加35%；（iv）可提取蛋白和可溶性蛋白含量分别提高5-12%和11-35%。硫氧还蛋白h在干粒中被高度还原，在吸胀后在零分离和纯合子中均被降解。α-淀粉酶活性的增加和蛋白质还原状态的提高伴随着蛋白质的分布从不溶部分向可溶部分的转变。结果表明，淀粉质胚乳的硫氧还蛋白h与邻近组织交流，从而调节其活性，特别是通过促进胚萌发和糊粉释放α-淀粉酶的出现。
Homozygous lines of barley overexpressing a wheat thioredoxin h transgene (up to 30-fold) were generated earlier by using a B1-hordein promoter with a signal peptide sequence for targeting to the protein body and found to be enriched in starch debranching enzyme (pullulanase). Here, we describe the effect of biochemically active, overexpressed thioredoxin h on germination and the onset of α-amylase activity. Relative to null segregant controls lacking the transgene, homozygotes overexpressing thioredoxin h effected (i) an acceleration in the rate of germination and appearance of α-amylase activity with a 1.6- to 2.8-fold increase in gibberellin A1 (GA1) content; (ii) a similar acceleration in the appearance of the α-amylase activity in deembryonated transgenic grain incubated with gibberellic acid; (iii) a 35% increase in the ratio of relative reduction (abundance of SH) of the propanol soluble proteins (hordein I fraction); and (iv) an increase in extractable and soluble protein of 5–12% and 11–35%, respectively. Thioredoxin h, which was highly reduced in the dry grain, was degraded in both the null segregant and homozygote after imbibition. The increase in α-amylase activity and protein reduction status was accompanied by a shift in the distribution of protein from the insoluble to the soluble fraction. The results provide evidence that thioredoxin h of the starchy endosperm communicates with adjoining tissues, thereby regulating their activities, notably by accelerating germination of the embryo and the appearance of α-amylase released by the aleurone.