ABSTRACT

Ipomoea trifida, the closest relative of sweetpotato, does not generally form storage roots, but some lines develop thick roots similar to the storage roots of the sweetpotato. Revealing the molecular mechanism of thick root development in I. trifida would help us understand the evolution of storage roots in the sweetpotato. In this study, we conducted a mapping method for quantitative trait loci (QTLs) known as QTL-seq, which is a kind of next-generation sequencing-based bulk segregant analysis. We performed QTL-seq using a backcross population (BC₁F₁) derived from two I. trifida lines: Mx23Hm, which does not show root-thickening; and 0431-1, which produces thick roots. The aim was to identify the QTL region involved in thick root development. As a result, a major QTL for root thickness (qRT1) was detected in the 2.94–8.71 Mb region of chr06 of Itr_r2.2, in both pot and field experiments. Six DNA markers were designed for qRT1 using InDels on chr06. Genotyping each BC₁F₁ individual based on these DNA markers agreed well with the SNP-Index of QTL-seq. Moreover, most individuals with 0431-1-type alleles of qRT1 developed thicker roots than individuals without 0431-1-type alleles of qRT1 in the BC₂F₂ population. The results of this study implied that qRT1 was an important QTL for regulating root thickness in I. trifida.

摘要

Ipomoea trifida是甘薯的近亲，一般不会形成贮藏根，但有些品系会发育出类似于甘薯贮藏根的粗根。揭示I. trifida粗根发育的分子机制将有助于我们了解甘薯中贮藏根的进化。在这项研究中，我们进行了一种称为 QTL-seq 的数量性状基因座 (QTL) 作图方法，这是一种基于下一代测序的批量分离分析。我们使用来自两个I. trifida的回交群体 (BC ₁ F _{1 ) 执行 QTL-seq}线：Mx23Hm，不显示根部增厚；和 0431-1，产生粗根。目的是确定参与粗根发育的 QTL 区域。结果，在盆栽和田间实验中，在 Itr_r2.2 的 chr06 的 2.94-8.71 Mb 区域中检测到了根厚度 ( qRT1 ) 的主要 QTL。使用 chr06 上的 InDels为qRT1设计了六个 DNA 标记。基于这些 DNA 标记对每个 BC ₁ F _{1个体进行基因分型与 QTL-seq 的 SNP-Index 一致。}此外，在 BC ₂ F _{2中，大多数具有}qRT1 0431-1 型等位基因的个体比没有 qRT1 0431-1 型等位基因的个体发育出更粗的根。人口。本研究结果提示qRT1是调控三叶草根粗度的重要QTL 。