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.

大豆在苗期常受渍水引发的低氧胁迫危害。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化大豆种质资源，解析苗期低氧胁迫下根系发育的表型变异。研究通过水培法对162份大豆种质的根系发育情况进行评价，并采用WinRHIZO根系分析系统，对胁迫处理前后低氧条件下的根系显著变化展开分析。结果显示，162份种质的根系低氧耐性存在显著表型变异。主成分分析表明，根系低氧耐性与种质起源国家存在关联。本研究筛选得到3份在低氧条件下根系发育能力极强的全新种质：Kokubu 7、Maetsue zairai 90B及Yahagi。此外，研究还通过土培法对筛选出的种质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。上述结果可为渍水频发区域的渍害防控提供重要参考依据。这3份根系耐低氧的大豆种质，可用于现代大豆品种耐渍性的遗传改良。