Introduction of glucan synthase into the cytosol in wheat endosperm causes massive maltose accumulation and represses starch synthesis.
Introduction of glucan synthase into the cytosol in wheat endosperm causes massive maltose accumulation and represses starch synthesis.
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将葡聚糖合酶引入小麦胚乳的细胞质中会导致大量麦芽糖积累并抑制淀粉合成。
DOI：
10.1111/tpj.15246
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Schreier TB
中科院分区：
文献类型：
--
作者：
Schreier TB
我们在小麦籽粒发育中的胚乳细胞的细胞质中表达了细菌葡聚糖合酶（农杆菌GlgA），以探索它是否可以从细胞质ADP-葡萄糖产生葡聚糖。转基因品系在籽粒灌浆期间具有高葡聚糖合酶活性，但不积累葡聚糖。相反，谷物中积累了非常高浓度的麦芽糖。由于含水量高，它们在发育过程中体积很大，成熟时谷物非常干瘪。淀粉合成严重减少。我们提出，由葡聚糖合酶合成的胞质葡聚糖立即被胞质 β-淀粉酶水解为麦芽糖。麦芽糖的积累导致了谷物发育过程中的高渗透势，吸收了过量的水分，拉伸了种皮和果皮。谷物成熟过程中水分的流失会导致谷物成熟时的收缩。麦芽糖的积累可能通过信号传导和毒性作用来解释转基因谷物中淀粉合成的减少。利用生物信息学，我们确定了可能导致麦芽糖积累的β-淀粉酶亚型。通过识别 TILLING 突变体或基因组编辑来去除这种亚型，结合异源葡聚糖合酶和葡聚糖分支酶的共表达，将来可能会通过淀粉和胞质葡聚糖的同时积累来提高碳水化合物的产量。
We expressed a bacterial glucan synthase (AgrobacteriumGlgA) in the cytosol of developing endosperm cells in wheat grains, to discover whether it could generate a glucan from cytosolic ADP‐glucose. Transgenic lines had high glucan synthase activity during grain filling, but did not accumulate glucan. Instead, grains accumulated very high concentrations of maltose. They had large volumes during development due to high water content, and very shrivelled grains at maturity. Starch synthesis was severely reduced. We propose that cytosolic glucan synthesized by the glucan synthase was immediately hydrolysed to maltose by cytosolic β‐amylase(s). Maltose accumulation resulted in a high osmotic potential in developing grain, drawing in excess water that stretched the seed coat and pericarp. Loss of water during grain maturation then led to shrinkage when the grains matured. Maltose accumulation is likely to account for the reduced starch synthesis in transgenic grains, through signalling and toxic effects. Using bioinformatics, we identify an isoform of β‐amylase likely to be responsible for maltose accumulation. Removal of this isoform through identification of TILLING mutants or genome editing, combined with co‐expression of heterologous glucan synthase and a glucan branching enzyme, may in future enable elevated yields of carbohydrate through simultaneous accumulation of starch and cytosolic glucan.
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影响因子：
2.9
作者：
J. Smirnova;A. Fernie;C. Spahn;M. Steup
通讯作者：
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DOI：
--
发表时间：
2015
期刊：
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作者：
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作者：
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Zeeman, Samuel C.
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DOI：
--
发表时间：
2000
期刊：
影响因子：
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作者：
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通讯作者：
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