Utilization of Imaging Approaches to Understand Chenopodium quinoa, a Model Plant to Study Salt Stress

Abstract

Chenopodium quinoa is an important crop that is known for its salt tolerance [1, 2]. Salinity is an osmotic stress and the accumulation of ions in the root zone causes a reduction in soil water availability, which negatively affects the uptake of essential nutrients, changes seed composition, and reduces biomass. Therefore, there is a need to develop highly productive crops under poor soils. This research used imaging and other approaches to examine the effect of salt stress on quinoa photosynthetic efficiency, salt bladder changes and chloroplast development. Sensitive and tolerant quinoa lines were examined under salt stress conditions when a concentration of 155 mM NaCl was applied. Electrical soil conductivity was monitored during the experiment to assure salt stress and at approximately two months old, leaf tissue was sampled and chloroplast and grana were characterized using a super-resolution approach called lattice structured illumination microscopy. Chloroplast structure was negatively affected by environmental factors such as the availability of water and minerals [3]. Salt-sensitive lines showed swelling of the chloroplast stroma and starch accumulation (Figure 1). Live tissue was also analyzed using reflection and fluorescence confocal microscopy, where epidermal salt bladders [4] images were acquired, visualized and analyzed in 3-D and the salt tolerant line showed bigger bladder volumes compared with control conditions (Figure 2). A more high-throughput approach was used by using PlantCV [5], an open-source image analysis software package targeted for plant phenotyping. This software helped count epidermal salt bladders using stereoscope images. The salt tolerant line had more salt bladders on the leaf surface than the sensitive line, which could be one of the mechanisms why this line tolerated more stress cause by the salt application (Figure 2). A comprehensive understanding of the quinoa salt tolerant mechanisms by employing multidisciplinary approaches is necessary for their effective incorporation into salt-sensitive crops for better crop yields under stressful environments. Chloroplast structure measured using a super-resolution approach called lattice structured illumination microscopy. Two different genotypes 37TES (salt sensitive) and QQ74 (salt tolerant) under two different treatments salt (+) and no salt conditions (-). A) Epidermal salt bladder images using reflection and fluorescence confocal microscopy. Volume quantification of two different genotypes 37TES (salt sensitive) and QQ74 (salt tolerant) under two different treatments salt (+) and no salt conditions (-). B) Epidermal salt bladder number quantification using PlantCV.

Plant phenotyping relevance

塩ストレスの生物学的解析を目的とするが、複数の画像取得・解析法とPlantCVを用いた塩腺の3D体積・個数の定量が主要な構成であり、植物形態形質の画像ベース表現型解析として中心的である。

Code and data availability

This is a two-page conference meeting report with no data availability statement, no public dataset or image deposit, and no author code release. PlantCV is cited as a generic open-source tool, not a paper-specific asset.

No evidence-backed public reproduction asset is currently recorded.