Multiscale NMR investigations of two anatomically contrasted genotypes of sorghum under watered conditions and during drought stress

Abstract

Today, in the presence of global warming, understanding how plants respond to drought stress is essential to meet the challenge of developing new cultivars and new irrigation strategies, consistent with the maintenance of crop productivity. In this context, the study of the relation between plants and water is of central interest for modeling their responses to biotic and abiotic constraints. Paradoxically, there are very few direct and noninvasive methods to quantify and measure the level and the flow of water in plants. The present work aims to develop a noninvasive methodology for living plant based on nuclear magnetic resonance (NMR) at low magnetic field and imaging (MRI) to tackle the issue of water quantity in plants. For this purpose, a portable NMR device measuring the signal level at 8 mT was built. This instrument addresses specific challenges such as miniaturization, accessibility, and overheating in order to maintain the plant intact of time over long period. Time dependence of the water content in sorghum plants is reported under abiotic stress as well as the fraction of transpirable soil water and the photosynthesis activity through the leaves. At high magnetic field (9.4 T), T2 maps were acquired on the same sorghum plants at two time points. The combination of these approaches allows us to identify ecophysiological biomarkers of drought stress. One particular interesting result concerns the spatial distribution of water in two anatomically contrasted sorghum genotypes.

Critical knowledge gaps and research priorities in global soil salinity

“…In addition, innovative experiments are needed to better understand the integrated plant response to water and salinity stress. For that purpose, high resolution geophysical methods (such as magnetic resonance imaging and neutron tomography) open new avenues to better quantify local concentration and potential gradients around roots and in plant tissues (Koch et al, 2019;Sidi-Boulenouar et al, 2019). Their application to plants subjected to combined stresses may help to visualize the spatio-temporal evolution of local gradients as a function of root and soil properties, evaporative demand, and soil salinity.…”

FijiRelax: Fast and noise-corrected estimation of MRI relaxation maps in 3D + t

“…Quantitative Magnetic Resonance Imaging (MRI) is a relevant technique to measure water availability and binding in animal or vegetal tissues. Among others, MRI is useful to decipher the impact of stresses on living samples (Sidi-Boulenouar et al, 2019). Reproducible measurements of anatomical and physiological changes can be obtained by quantitative mapping of biomarkers (see Figure 1-a) such as proton density (PD) and magnetization relaxation times (T1, T2) in 2D images (Borisjuk et al, 2012 ;Dusschoten et al, 2016).…”