Abstract
Organic acids secreted from plant roots play important roles in various biological processes including nutrient acquisition, metal detoxification, and pathogen attraction. The secretion of organic acids may be affected by various conditions such as plant growth stage, nutrient deficiency, and abiotic stress. For example, when white lupin (Lupinus albus L.) is exposed to phosphorus (P)-deficient conditions, the secretion of citrate acid from its proteoid roots significantly increases (Neumann et al., 1999). This protocol describes a method for the collection and measurement of the efflux of organic acids (oxalate, malate, and citrate) from the roots of rice cultivar Nipponbare (‘Nip’) under different nitrogen forms (NH4+ and NO3-), together with different P supply (+P and -P) conditions.
Keywords: Organic acids, Rice, Collection, Measurement, Ion chromatography
Background
In addition to enzymatic methods (Delhaize et al., 1993) and high-performance liquid chromatography (HPLC) (Chen et al., 2013), ion chromatography is another widely used method for the determination of organic acids, which has previously been employed to detect the significant increase in oxalate content in taro root exudates during Al3+ stress (Ma and Miyasaka, 1998). Compared to ion chromatography, alternative methods have their own defects. For example, enzymatic methods require the use of enzymes that can easily undergo denaturation. Moreover, it is difficult to distinguish oxalate acid from Cl- peaks by HPLC. Here, we describe a method for analyzing organic acids secreted by rice roots using ion chromatography. This method could be used in the analysis of organic acids that are secreted by other hydroponically cultivated plants.
Materials and Reagents
Equipment
Procedure
Notes:
Data analysis
Recipes
Acknowledgments
The methods to collect and concentrate organic acids were modified from Ma et al. (2004), the measurement of organic acids content was modified from Zhu et al. (2015) and developed in the Ren Fang Shen’s Lab-Institute of Soil Science, Chinese Academy of Science. This work was supported by the National Key Basic Research Program of China (No. 2014CB441000), Natural Science Foundation of China (31501825) and the ‘Strategic Priority Research Program’ of the Chinese Academy of Sciences (Nos. XDB15030302 and XDB15030202).
References
If you have any questions/comments about this protocol, you are highly recommended to post here. We will invite the authors of this protocol as well as some of its users to address your questions/comments. To make it easier for them to help you, you are encouraged to post your data including images for the troubleshooting.