Collaborative Innovation Center of Henan Grain Crops, State Key Laboratory of Wheat and Maize Crop Science, College of Life Sciences, Henan Agricultural University, Zhengzhou, China.
Laboratory of Plant Genetics and Breeding, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, Japan.
J Exp Bot. 2019 Nov 18;70(21):6475-6487. doi: 10.1093/jxb/erz403.
Zea nicaraguensis is a wild relative of Zea mays subsp. mays (maize) that has high waterlogging tolerance. One of its traits is constitutive aerenchyma formation (CAF) in roots and this may be one of the reasons for the tolerance, but it has not yet been proven by comparing plants that differ only in CAF in the same genetic background. We therefore produced an introgression line AE24-50-44-91 (IL-AE91) possessing four quantitative trait loci for CAF from Z. nicaraguensis in the background of maize (inbred line Mi29). The degree of root CAF in IL-AE91 was intermediate between that of Mi29 and Z. nicaraguensis. Seedlings of IL-AE91 grown aerobically were more tolerant to transfer to oxygen-deficient conditions than were Mi29 seedlings. On day 2 of oxygen deficiency, the root extension rate and viability of root-tip cells in IL-AE91 were ~2.7 and ~1.3 times greater, respectively, than they were in Mi29. On day 4, the area of aerenchyma at 80 mm from the root tips was ~1.5 times greater in IL-AE91 and radial oxygen loss from the apical parts of roots was ~3.4 times higher than in Mi29. These results demonstrate that CAF reduces the stress from low external oxygen levels caused by soil waterlogging.
大刍草是玉米（玉米亚种）的野生近缘种，具有较强的耐淹水能力。其特性之一是在根系中形成组成型通气组织（CAF），这可能是其耐淹水的原因之一，但尚未通过比较在相同遗传背景下仅在 CAF 上存在差异的植物来证明。因此，我们从大刍草中产生了一个具有四个组成型通气组织（CAF）数量性状位点的导入系 AE24-50-44-91（IL-AE91），该导入系位于玉米（自交系 Mi29）的背景下。IL-AE91 的根系 CAF 程度介于 Mi29 和大刍草之间。在有氧条件下生长的 IL-AE91 幼苗比 Mi29 幼苗更能耐受缺氧条件的转变。在缺氧的第 2 天，IL-AE91 的根伸长率和根尖细胞活力分别比 Mi29 高约 2.7 倍和 1.3 倍。在第 4 天，从根尖 80mm 处的通气组织面积 IL-AE91 比 Mi29 大 1.5 倍，根顶端部分的径向耗氧量比 Mi29 高约 3.4 倍。这些结果表明，CAF 减轻了由土壤淹水引起的低外部氧气水平带来的胁迫。
