Establishment of resistance to stresses caused by soil moisture fluctuation through strengthening the ability of plastic response ability of root system in rice

本研究旨在研究植物随着环境条件的变化而改变其发育的能力在作物适应干旱和土壤水分波动胁迫等水分胁迫中的功能作用。我们利用水稻SNP种质集、日本晴与Kasalath杂交衍生的染色体片段置换系、IR系，以及包括NERICA在内的几个有希望的抗逆性基因，进行了一系列实验，以评估根可塑性的功能作用。我们采用了根箱-插板法、斜管法、安装了能在干旱胁迫强度中产生梯度的线源喷洒系统的试验台和能在田间条件下增加生根深度的斜床，对根系性状进行了表型鉴定。这些结果一致表明，除了深根，根系的可塑性发育是植物适应水分胁迫的关键特征。我们还发现，整个根系发育的可塑性对于逐渐干旱的响应是重要的，而侧根发育和通风组织形成的可塑性对于短暂干旱和缺氧条件的响应是重要的。我们定量地展示了水分胁迫下根系可塑性对干物质生产的贡献是通过提高水分吸收来实现的。

This study aimed to examine the functional roles of the ability of the plant to change its development as environmental conditions change, which is known as phenotypic plasticity in crop adaptation to water stress such as drought as well as soil moisture fluctuation stress, and. We conducted a series of experiments to evaluate the functional roles of root plasticity by using various accessions/populations such as OryzaSNP germplasm set, chromosome segment substitution lines (CSSL) derived from Nipponbare and Kasalath cross, IR 64 INLs and a few promising genotypes for stress tolerance including NERICA (New Rice for Africa that is an interspecific cross between Oryza sativa and Oryza glaberrima). We used the rootbox-pinboard method, slant tube method, experimental bed installed with line source sprinkler system that can create gradient in drought stress intensities, and sloping bed that can create increasing rooting depths under field conditions for phenotyping root traits. These results consistently showed that in addition to deep roots, the plastic development of the root system is a key trait for plant adaptation to water stress. We also found that the plasticity in development of the entire root system is important in response to progressive drought, while that in lateral root development and aerenchyma formation is important in response to transient drought and O2 deficient conditions. We quantitatively showed the contributions of root plasticity to dry matter production through enhanced water uptake under water stress.