Natural Polymorphisms in Arabidopsis Result in Wide Variation or Loss of the Amylose Component of Starch.
Natural Polymorphisms in Arabidopsis Result in Wide Variation or Loss of the Amylose Component of Starch.
复制标题
拟南芥中的天然多态性导致淀粉直链淀粉成分的广泛变化或损失。
DOI：
10.1104/pp.19.01062
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发表时间：
2020
期刊：
影响因子：
7.4
通讯作者：
Seung D
中科院分区：
文献类型：
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作者：
Seung D
淀粉颗粒含有两种葡萄糖聚合物，支链淀粉和直链淀粉。直链淀粉占迄今为止研究的所有天然淀粉的约10%至30%（w/w），但是产生无直链淀粉的淀粉的作物和模式植物的突变体通常在生长、淀粉含量和颗粒形态方面与其野生型对应物没有区别。由于直链淀粉的功能和适应意义是未知的，我们问是否有直链淀粉合成的野生，未栽培的物种的自然遗传变异。我们检测了1,135个已测序的拟南芥（Arabidopsis thaliana）基因组中GBSS（编码负责直链淀粉合成的酶）的多态性。我们鉴定了18份预测具有影响蛋白质功能的GBSS多态性的材料，其中5份材料产生的淀粉不含或极低直链淀粉（< 0.5% [w/w]）。另外8份材料的直链淀粉含量显著低于或高于Col-0（9% [w/w]），范围为5%至12%（w/w）。我们研究了多态性对GBSS功能的影响，并揭示了GBSS序列变异导致不同直链淀粉含量的三种机制：（1）改变GBSS丰度，（2）改变GBSS活性，（3）改变GBSS结合蛋白质靶向淀粉1的亲和力-一种将GBSS靶向淀粉颗粒的蛋白质。这些研究结果表明，叶片中的直链淀粉是不是必不可少的一些自然发生的拟南芥基因型的生存能力，至少在短时间尺度和在某些环境条件下，并打开一个机会，探索直链淀粉的适应意义。
Starch granules contain two Glc polymers, amylopectin and amylose. Amylose makes up approximately 10% to 30% (w/w) of all natural starches thus far examined, but mutants of crop and model plants that produce amylose-free starch are generally indistinguishable from their wild-type counterparts with respect to growth, starch content, and granule morphology. Since the function and adaptive significance of amylose are unknown, we asked whether there is natural genetic variation in amylose synthesis within a wild, uncultivated species. We examined polymorphisms among the 1,135 sequenced accessions of Arabidopsis (Arabidopsis thaliana) inGRANULE-BOUND STARCH SYNTHASE(GBSS), encoding the enzyme responsible for amylose synthesis. We identified 18 accessions that are predicted to have polymorphisms inGBSSthat affect protein function, and five of these accessions produced starch with no or extremely low amylose (< 0.5% [w/w]). Eight further accessions had amylose contents that were significantly lower or higher than that of Col-0 (9% [w/w]), ranging from 5% to 12% (w/w). We examined the effect of the polymorphisms on GBSS function and uncovered three mechanisms by which GBSS sequence variation led to different amylose contents: (1) altered GBSS abundance, (2) altered GBSS activity, and (3) altered affinity of GBSS for binding PROTEIN TARGETING TO STARCH1—a protein that targets GBSS to starch granules. These findings demonstrate that amylose in leaves is not essential for the viability of some naturally occurring Arabidopsis genotypes, at least over short timescales and under some environmental conditions and open an opportunity to explore the adaptive significance of amylose.