Background

The root system plays a major role in plant growth and development and root system architecture is reported to be the main trait related to plant adaptation to drought. However, phenotyping root systems in situ is not suited to high-throughput methods, leading to the development of non-destructive methods for evaluations in more or less controlled root environments. This study used a root phenotyping platform with a panel of 20 japonica rice accessions in order to: (i) assess their genetic diversity for a set of structural and morphological root traits and classify the different types; (ii) analyze the plastic response of their root system to a water deficit at reproductive phase and (iii) explore the ability of the platform for high-throughput phenotyping of root structure and morphology.

Results

High variability for the studied root traits was found in the reduced set of accessions. Using eight selected traits under irrigated conditions, five root clusters were found that differed in root thickness, branching index and the pattern of fine and thick root distribution along the profile. When water deficit occurred at reproductive phase, some accessions significantly reduced root growth compared to the irrigated treatment, while others stimulated it. It was found that root cluster, as defined under irrigated conditions, could not predict the plastic response of roots under drought.

Conclusions

This study revealed the possibility of reconstructing the structure of root systems from scanned images. It was thus possible to significantly class root systems according to simple structural traits, opening up the way for using such a platform for medium to high-throughput phenotyping. The study also highlighted the uncoupling between root structures under non-limiting water conditions and their response to drought.

中文翻译：

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一套粳稻种质的表型根系：结构性状能否预测干旱响应？

背景

根系在植物的生长发育中起着重要作用，据报道根系结构是植物适应干旱的主要特征。但是，原位表型根系不适用于高通量方法，导致开发了用于在或多或少受控制的根系环境中进行评估的非破坏性方法。这项研究使用了一个带有20个粳稻品种的根表型平台，以便：（i）评估其遗传多样性，以获得一组结构和形态根特征，并对不同类型进行分类；（ii）分析其根系对生殖期水分亏缺的塑性响应，以及（iii）探索平台进行根结构和形态高通量表型分析的能力。

结果

在减少的种质中发现了所研究根系性状的高度变异性。在灌溉条件下使用八个选定的性状，发现五个根簇，它们的根粗细，分支指数以及沿剖面的细根和粗根分布模式不同。当生殖阶段出现缺水时，与灌溉处理相比，某些种质显着降低了根系生长，而另一些则刺激了根系生长。发现在灌溉条件下定义的根簇不能预测干旱条件下根的塑性响应。

结论

这项研究揭示了从扫描图像重建根系结构的可能性。因此，有可能根据简单的结构特征对根系进行显着分类，从而开辟了使用这种平台进行中高通量表型鉴定的方式。该研究还强调了非限制性水分条件下根系结构与干旱响应之间的解偶联。