Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas, Convolvulaceae) complex.
Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas, Convolvulaceae) complex.
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甘薯（Ipomoea batatas，旋花科）复合体中核 DNA 含量和花粉大小随多倍化的变化。
作者：
S. Srisuwan;Darasingh Sihachakr;Joan Martín;Joan Vallès;Adrienne Ressayre;Spencer Brown;Sonja Siljak
我们在甘薯 (Ipomoea batatas) 中研究了基因组大小进化及其与花粉粒大小的关系，甘薯是一种与二倍体和四倍体物种密切相关的重要经济作物，评估了来自 5 个甘薯物种、10 个甘薯品种和两个外类群的 22 个种质的核 DNA 含量。使用流式细胞术测定核DNA量。使用扫描和透射电子显微镜研究花粉粒。六倍体红薯的 2C DNA 含量范围为 3.12-3.29 pg；平均单倍体基因组大小为 0.539 pg (527 Mbp)，与相关的二倍体种质相似。在四倍体物种 I. trifida 和 I. tabascana 中，2C DNA 含量分别为 2.07 和 2.03 pg。在与甘薯密切相关的二倍体物种中，例如I. × leucantha、I. tiliacea、I. trifida 和 I. triloba，2C DNA 含量为 1.01-1.12 pg。然而，两个二倍体外群物种 I. setosa 和 I. purpurea 与其他二倍体物种明显不同，2C 为 1.47-1.49 pg；它们也有更大的染色体。 I. 红薯基因组含有 60.0% AT 碱基。该复合体中 DNA 含量和倍性水平呈正相关。在 I. batatas 和更密切相关的物种 I. trifida 中，基因组大小和倍性水平与花粉大小相关。我们的结果使我们能够提出目前提出的六倍体红薯形成的替代或补充假设。
Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa. Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy. 2C DNA content of hexaploid I. batatas ranged between 3.12-3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana, 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. ×leucantha, I. tiliacea, I. trifida and I. triloba, 2C DNA content was 1.01-1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea, were clearly different from the other diploid species, with 2C of 1.47-1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases. DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida, the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas.