Changes in spatiotemporal protein and amino acid gradients in wheat caryopsis after N-topdressing
Changes in spatiotemporal protein and amino acid gradients in wheat caryopsis after N-topdressing
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追施氮肥后小麦颖果蛋白质和氨基酸时空梯度的变化
DOI：
10.1016/j.plantsci.2019.110336
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发表时间：
2020
期刊：
影响因子：
5.2
通讯作者：
Kim Henrik Hebelstrup
中科院分区：
文献类型：
--
作者：
Yingxin Zhong;Nanna Hjort Vidkjær;Julio A. Massange-Sanchez;Bente Birgitte Laursen;René Gislum;Søren Borg;Dong Jiang;Kim Henrik Hebelstrup
由于蛋白质含量的径向梯度，小麦籽粒氮含量在不同粒级间表现出较大的差异。我们确定了时空机制如何调节这一点。蛋白质梯度在花后19 d出现明显变化，糊粉层和种皮中N含量最高，外胚乳次之，中胚乳和内胚乳最低。采用激光显微切割、qRT-PCR和LC-MS分别从糊粉层、外胚乳、中胚乳、内胚乳和传递细胞中切割组织，测量基因表达以及游离氨基酸和蛋白结合氨基酸的水平。结果表明，不同FAA运输途径在籽粒灌浆期平行运转，但籽粒蛋白质梯度并不遵循贮藏蛋白质的空间表达规律。此外，还进行了两种追氮时期的试验，分别在顶三叶（标准时期）和顶一叶（延迟时期）出现时追氮，发现延迟追氮可提高氨基酸供应和蛋白质合成能力。这些结果为深入了解胚乳中蛋白质合成和氨基酸转运途径提供了依据，并为提高具有更高品质的特殊珍珠小麦提供了目标。
Wheat grain nitrogen content displays large variations within different pearling fractions of grains because of radial gradients in the protein content. We identified how spatiotemporal mechanisms regulate this. The protein gradients emerged clearly at 19 days after anthesis, with the highest N content in aleurone and seed coat, followed by outer endosperm, whereas the lowest was in middle and inner endosperm. Laser microdissection, qRT-PCR and LC–MS were used to dissect tissue from aleurone, outer endosperm, middle endosperm, inner endosperm and transfer cells, measure gene expression and levels of free and protein-bound amino acids, respectively. The results showed that different FAA transportation pathways worked in parallel during grain filling stage while the grain protein gradient did not follow spatial expression of storage proteins. Additionally, two nitrogen (N) topdressing timings were conducted, either at the emergence of top third leaf (standard timing) or top first leaf (delayed timing), finding that delayed N topdressing enhanced both amino acids supply and protein synthesis capacity. The results provide insight into protein synthesis and amino acid transport pathways in endosperm and suggest targets for the enhancement of specialty pearled wheat with higher quality.