International Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China.
Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Int J Mol Sci. 2019 Feb 6;20(3):699. doi: 10.3390/ijms20030699.
Waterlogging is a serious environmental problem that limits agricultural production in low-lying rainfed areas around the world. The major constraint that plants face in a waterlogging situation is the reduced oxygen availability. Accordingly, all previous efforts of plant breeders focused on traits providing adequate supply of oxygen to roots under waterlogging conditions, such as enhanced aerenchyma formation or reduced radial oxygen loss. However, reduced oxygen concentration in waterlogged soils also leads to oxygen deficiency in plant tissues, resulting in an excessive accumulation of reactive oxygen species (ROS) in plants. To the best of our knowledge, this trait has never been targeted in breeding programs and thus represents an untapped resource for improving plant performance in waterlogged soils. To identify the quantitative trait loci (QTL) for ROS tolerance in barley, 187 double haploid (DH) lines from a cross between TX9425 and Naso Nijo were screened for superoxide anion (O₂) and hydrogen peroxide (H₂O₂)-two major ROS species accumulated under hypoxia stress. We show that quantifying ROS content after 48 h hypoxia could be a fast and reliable approach for the selection of waterlogging tolerant barley genotypes. The same QTL on chromosome 2H was identified for both O₂ (QSO.TxNn.2H) and H₂O₂ (QHP.TxNn.2H) contents. This QTL was located at the same position as the QTL for the overall waterlogging and salt tolerance reported in previous studies, explaining 23% and 24% of the phenotypic variation for O₂ and H₂O contents, respectively. The analysis showed a causal association between ROS production and both waterlogging and salt stress tolerance. Waterlogging and salinity are two major abiotic factors affecting crop production around the globe and frequently occur together. The markers associated with this QTL could potentially be used in future breeding programs to improve waterlogging and salinity tolerance.
水涝是一个严重的环境问题，限制了世界各地低地雨养地区的农业生产。植物在水涝情况下面临的主要限制是氧气供应减少。因此，植物育种者以前的所有努力都集中在提供水涝条件下根系充足氧气供应的特性上，例如增强通气组织形成或减少径向氧气损失。然而，水涝土壤中氧气浓度的降低也会导致植物组织缺氧，导致植物中活性氧（ROS）的过度积累。据我们所知，这种特性从未在育种计划中得到过关注，因此代表了在水涝土壤中提高植物性能的未开发资源。为了鉴定大麦中 ROS 耐受性的数量性状位点（QTL），我们从 TX9425 和 Naso Nijo 的杂交后代中筛选了 187 个双单倍体（DH）系，以检测缺氧胁迫下积累的超氧阴离子（O₂）和过氧化氢（H₂O₂）——两种主要的 ROS 物质。我们表明，在缺氧 48 小时后定量 ROS 含量可以快速可靠地选择耐水涝的大麦基因型。在 2H 染色体上鉴定到了与 O₂（QSO.TxNn.2H）和 H₂O₂（QHP.TxNn.2H）含量相关的相同 QTL。该 QTL 位于先前研究中报道的整体水涝和耐盐性 QTL 的相同位置，分别解释了 O₂和 H₂O₂含量表型变异的 23%和 24%。分析表明 ROS 产生与水涝和耐盐性之间存在因果关系。水涝和盐度是影响全球作物生产的两个主要非生物因素，并且经常同时发生。与该 QTL 相关的标记物可能在未来的育种计划中用于提高水涝和盐度耐受性。
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