Phenotypic variation in root development of 162 soybean accessions under hypoxia condition at the seedling stage

Soybean is often damaged by hypoxia caused by waterlogging at the seedling stage. Hypoxia severely inhibits root development and retards plant growth. We aimed to clarify phenotypic variation in root development under hypoxia condition at the seedling stage using diverse soybean accessions. Root development in 162 accessions was evaluated in hydroponic culture. Substantial changes under hypoxia were investigated by means of WinRHIZO analysis before and after the treatment. We found significant phenotypic variation in hypoxia tolerance in root among the 162 accessions. A principal components analysis indicated an association between hypoxia tolerance and the country of origin. We found three new accessions which have a high ability to develop roots under hypoxia (Kokubu 7, Maetsue zairai 90B, and Yahagi). Root development in selected accessions was also evaluated in soil culture. Root development levels in hydroponic and soil culture were significantly correlated. These results will provide important information on waterlogging damage in regions where waterlogging occurs. The three accessions with hypoxia-tolerant roots might be useful for genetic improvement of waterlogging tolerance of modern soybean varieties.

大豆在苗期常受涝害引发的低氧胁迫损伤。低氧会严重抑制根系发育，延缓植株生长。本研究旨在利用多样的大豆种质资源，阐明苗期低氧条件下根系发育的表型变异。我们采用水培法对162份大豆种质的根系发育状况进行了评价。借助WinRHIZO根系分析（WinRHIZO）技术，我们对低氧处理前后植株根系的显著变化展开了研究。结果显示，162份种质的根系耐低氧性存在显著表型变异。主成分分析表明，根系耐低氧性与其起源国存在关联。我们筛选出3份在低氧条件下根系发育能力较强的新种质：Kokubu 7、Maetsue zairai 90B及Yahagi。我们还通过土培法对筛选出的种质材料的根系发育情况进行了评价。水培与土培条件下的根系发育水平呈显著相关。上述研究结果可为涝害发生地区的涝害防控提供重要参考。这3份根系耐低氧的种质，可为现代大豆品种的耐涝性遗传改良提供宝贵的遗传资源。