Forage Crop Research Division, NARO Institute of Livestock and Grassland Science, 768 Senbonmatsu, Nasushiobara, Tochigi 329-2793, Japan.
Ann Bot. 2013 Oct;112(6):1125-39. doi: 10.1093/aob/mct160. Epub 2013 Jul 21.
Nicaraguan teosinte (Zea nicaraguensis), a species found in frequently flooded areas, provides useful germplasm for breeding flooding-tolerant maize (Z. mays subsp. mays). The objective of this study was to select flooding-tolerant lines using a library of introgression lines (ILs), each containing a chromosome segment from Z. nicaraguensis in the maize inbred line Mi29.
To produce the ILs, a single F1 plant derived from a cross between maize Mi29 and Z. nicaraguensis was backcrossed to Mi29 three times, self-pollinated four times and genotyped using simple sequence repeat markers. Flooding tolerance was evaluated at the seedling stage under reducing soil conditions.
By backcrossing and selfing, a series of 45 ILs were developed covering nearly the entire maize genome. Five flooding-tolerant lines were identified from among the ILs by evaluating leaf injury. Among these, line IL#18, containing a Z. nicaraguensis chromosome segment on the long arm of chromosome 4, showed the greatest tolerance to flooding, suggesting the presence of a major quantitative trait locus (QTL) in that region. The presence of the QTL was verified by examining flooding tolerance in a population segregating for the candidate region of chromosome 4. There was no significant relationship between the capacity to form constitutive aerenchyma and flooding tolerance in the ILs, indicating the presence of other factors related to flooding tolerance under reducing soil conditions.
A flooding-tolerant genotype, IL#18, was identified; this genotype should be useful for maize breeding. In addition, because the chromosome segments of Z. nicaraguensis in the ILs cover nearly the entire genome and Z. nicaraguensis possesses several unique traits related to flooding tolerance, the ILs should be valuable material for additional QTL detection and the development of flooding-tolerant maize lines.
尼加拉瓜类蜀黍（Zea nicaraguensis）是一种生长在常被洪水淹没地区的物种，为培育耐淹玉米（Zea mays subsp. mays）提供了有用的种质资源。本研究的目的是利用包含来自玉米自交系 Mi29 的尼加拉瓜类蜀黍染色体片段的导入系（ILs）文库选择耐淹系。
为了产生 ILs，从玉米 Mi29 和尼加拉瓜类蜀黍杂交的 F1 单株与 Mi29 回交三次，自交四次，并使用简单序列重复标记进行基因型分析。在土壤条件降低的情况下，在幼苗期评估耐淹性。
通过回交和自交，开发了一系列包含几乎整个玉米基因组的 45 个 ILs。通过评估叶片损伤，从 ILs 中鉴定出 5 个耐淹系。其中，IL#18 号系含有来自染色体 4 长臂上的尼加拉瓜类蜀黍染色体片段，对洪水的耐受性最强，表明该区域存在一个主要的数量性状位点（QTL）。通过检查染色体 4 候选区域的分离群体的耐淹性，验证了 QTL 的存在。在 ILs 中，形成组成型通气组织的能力与耐淹性之间没有显著关系，表明在土壤条件降低的情况下，存在与耐淹性相关的其他因素。
鉴定出了一个耐淹基因型 IL#18，该基因型应可用于玉米育种。此外，由于 ILs 中的尼加拉瓜类蜀黍染色体片段几乎覆盖了整个基因组，并且尼加拉瓜类蜀黍具有几种与耐淹性相关的独特特性，因此 ILs 应该是用于进一步检测 QTL 和开发耐淹玉米系的有价值的材料。
