MsPG4-mediated hydrolysis of pectins increases the cell wall extensibility and aluminum resistance of alfalfa,Plant and Soil

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MsPG4-mediated hydrolysis of pectins increases the cell wall extensibility and aluminum resistance of alfalfa
Plant and Soil ( IF 3.9 ) Pub Date : 2022-04-13 , DOI: 10.1007/s11104-022-05431-3
Nana Fan ₁ , Wuwu Wen ₁ , Li Gao ₁ , Aimin Lv ₁ , Liantai Su ₁ , Peng Zhou ₁ , Yuan An _{1,

2}

Affiliation

Background and aims

Aluminum (Al) stress is a global problem that inhibits root growth and crop production in acidic soils. The inhibitive effect is greatly attributed to the reduction of cell wall elasticity. The present study aimed to investigate the function of a polygalacturonase gene MsPG4 in regulating cell wall extensibility and alfalfa resistance to Al stress.

Methods

The transgenic alfalfa plants of overexpression (MsPG4-OE) and knockdown (MsPG4-RNAi) of MsPG4 were treated with or without 100 µM AlCl₃. The methods of field emission scanning electron microscope, transmission electron microscope and atomic force microscopy were used in physiological and histological analysis.

Results

The relative root elongation was higher in MsPG4-OE lines and lower in MsPG4-RNAi lines than wild type (WT) plants under Al stress. Al contents in root tips and cell wall decreased in MsPG4-OE lines but increased in MsPG4-RNAi lines, which positively related to their pectin contents. The contents of water soluble pectin (WSP) and chelator soluble pectin (CSP) decreased in MsPG4-OE lines and increased in MsPG4-RNAi lines in the absence or presence of Al compared to WT plants. Consequently, the dimensions of the two pectin’s molecules reduced, the porosity and extensibility of cell wall increased in MsPG4-OE lines comparted to WT plants under Al stress.

Conclusions

MsPG4 effectively increases the cell wall extensibility and Al resistance of alfalfa via hydrolysis of pectins in the cell wall.

中文翻译：

MsPG4介导的果胶水解增加了紫花苜蓿的细胞壁延伸性和铝抗性

背景和目标

铝 (Al) 胁迫是抑制酸性土壤中根系生长和作物生产的全球性问题。抑制作用很大程度上归因于细胞壁弹性的降低。本研究旨在研究多聚半乳糖醛酸酶基因MsPG4在调节细胞壁延伸性和苜蓿对Al胁迫的抗性中的作用。

方法

用或不用100 µM AlCl _{3处理过表达(}MsPG4 -OE)和MsPG4敲低( MsPG4 -RNAi)的转基因紫花苜蓿植物。采用场发射扫描电子显微镜、透射电子显微镜和原子力显微镜等方法进行生理和组织学分析。

结果

在铝胁迫下，与野生型 (WT) 植物相比，MsPG4 -OE 系的相对根伸长率较高，而 MsPG4 -RNAi 系中的相对根系伸长率较低。MsPG4 -OE株系根尖和细胞壁Al含量降低，MsPG4 -RNAi株系增加，与果胶含量呈正相关。与 WT 植物相比，在不存在或存在 Al 的情况下，水溶性果胶 (WSP) 和螯合剂可溶性果胶 (CSP) 的含量在 MsPG4 -OE 系中降低，而在MsPG4 -RNAi 系中增加。因此，在铝胁迫下，与WT植物相比， MsPG4- OE系中两种果胶分子的尺寸减小，细胞壁的孔隙率和延伸性增加。