The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, Shaanxi, China.
Theor Appl Genet. 2019 May;132(5):1487-1503. doi: 10.1007/s00122-019-03294-4. Epub 2019 Feb 7.
We discovered that endopolyploidization is common in various organs and tissues of maize at different development stages. Endopolyploidy is not specific in maize germplasm populations. Endopolyploidy is caused by DNA endoreplication, a special type of mitosis with normal DNA synthesis and a lack of cell division; it is a common phenomenon and plays an important role in plant development. To systematically study the distribution pattern of endopolyploidy in maize, flow cytometry was used to determine the ploidy by measuring the cycle (C) value in various organs at different developmental stages, in embryos and endosperm during grain development, in roots under stress conditions, and in the roots of 119 inbred lines from two heterotic groups, Shaan A and Shaan B. Endopolyploidy was observed in most organs at various developmental stages except in expanded leaves and filaments. The endosperm showed the highest C value among all organs. During tissue development, the ploidy increased in all organs except the leaves. In addition, the endopolyploidization of the roots was significantly affected by drought stress. Multiple comparisons of the C values of seven subgroups revealed that the distribution of endopolyploidization was not correlated with the population structure. A correlation analysis at the seedling stage showed a positive relationship between the C value and both the length of the whole plant and the length of main root. A genome-wide association study (GWAS) identified a total of 9 significant SNPs associated with endopolyploidy (C value) in maize, and 8 candidate genes that participate in cell cycle regulation and DNA replication were uncovered in 119 maize inbred lines.
我们发现，多倍体化在不同发育阶段的玉米不同器官和组织中很常见。多倍体化在玉米种质群体中并不特异。多倍体化是由 DNA 内复制引起的，这是一种特殊的有丝分裂类型，具有正常的 DNA 合成但缺乏细胞分裂；它是一种常见现象，在植物发育中起着重要作用。为了系统研究玉米中多倍体化的分布模式，我们使用流式细胞术通过测量不同发育阶段各器官、胚和胚乳发育过程中的 C 值、在胁迫条件下的根以及来自两个杂种群（陕 A 和陕 B）的 119 个自交系的根中的 C 值来确定倍性。除了展开的叶片和花丝外，在大多数发育阶段的器官中都观察到了多倍体化。所有器官中，胚乳的 C 值最高。在组织发育过程中，除叶片外，所有器官的倍性都增加了。此外，根系的多倍体化受到干旱胁迫的显著影响。对七个亚组的 C 值进行多重比较发现，多倍体化的分布与群体结构无关。幼苗阶段的相关分析表明，C 值与整株长度和主根长度呈正相关。对玉米进行全基因组关联研究（GWAS）共鉴定出 9 个与多倍体化（C 值）相关的显著 SNP，在 119 个玉米自交系中发现了 8 个参与细胞周期调控和 DNA 复制的候选基因。
