Fruits are complex organs that are spatially regulated during development. Limited phenotyping capacity at cell and tissue levels is one of the main obstacles to our understanding of the coordinated regulation of the processes involved in fruit growth and quality. In this study, the spatial evolution of biophysical and metabolic traits of peach and apple fruit was investigated during fruit development. In parallel, the multi‐exponential relaxation times and apparent microporosity were assessed by quantitative magnetic resonance imaging (MRI). The aim was to identify the possible relationships between MRI parameters and variations in the structure and composition of fruit tissues during development so that transverse relaxation could be proposed as a biomarker for the assessment of the structural and functional evolution of fruit tissues during growth. The study provides species‐specific data on developmental and spatial variations in density, cell number and size distribution, insoluble and soluble compound accumulation and osmotic and water potential in the fruit mesocarp. Magnetic resonance imaging was able to capture tissue evolution and the development of pericarp heterogeneity by accessing information on cell expansion, water status and distribution at cell level, and microporosity. Changes in vacuole‐related transverse relaxation rates were mostly explained by cell/vacuole size. The impact of cell solute composition, microporosity and membrane permeability on relaxation times is also discussed. The results demonstrate the usefulness of MRI as a tool to phenotype fruits and to access important physiological data during development, including information on spatial variability.

中文翻译：

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桃和苹果果实定量磁共振成像参数的时空变化及其与生物物理和代谢特性的关系

水果是复杂的器官，在发育过程中受到空间调节。在细胞和组织水平上有限的表型能力是我们了解与果实生长和品质有关的过程的协调调控的主要障碍之一。在这项研究中，研究了桃和苹果果实在发育过程中生物物理和代谢性状的空间演变。同时，通过定量磁共振成像（MRI）评估了多指数弛豫时间和表观微孔率。目的是确定发育过程中MRI参数与水果组织的结构和组成变化之间的可能关系，从而可以提出横向松弛作为评估水果组织在生长过程中结构和功能演变的生物标记。该研究提供了果皮中密度，细胞数量和大小分布，不溶和可溶化合物积累以及渗透和水势的发育和空间变化的特定物种数据。磁共振成像能够通过访问有关细胞膨胀，水状态和细胞水平分布以及微孔性的信息来捕获组织进化和果皮异质性的发展。液泡相关的横向松弛率的变化主要由细胞/毛细血管大小解释。还讨论了细胞溶质组成，微孔和膜通透性对弛豫时间的影响。结果表明，MRI可以作为水果表型和在发育过程中获取重要生理数据（包括空间变异性信息）的工具。