Characterization of the Embryogenic Tissue of the Norway Spruce Including a Transition Layer between the Tissue and the Culture Medium by Magnetic Resonance Imaging

The paper describes the visualization of the cells (ESEs) and mucilage (ECMSN) in an embryogenic tissue via magnetic resonance imaging (MRI) relaxometry measurement combined with the subsequent multi-parametric segmentation. The computed relaxometry maps T₁ and T₂ show a thin layer (transition layer) between the culture medium and the embryogenic tissue. The ESEs, mucilage, and transition layer differ in their relaxation times T₁ and T₂; thus, these times can be used to characterize the individual parts within the embryogenic tissue. The observed mean values of the relaxation times T₁ and T₂ of the ESEs, mucilage, and transition layer are as follows: 1469 ± 324 and 53 ± 10 ms, 1784 ± 124 and 74 ± 8 ms, 929 ± 164 and 32 ± 4.7 ms, respectively. The multi-parametric segmentation exploiting the T₁ and T₂ relaxation times as a classifier shows the distribution of the ESEs and mucilage within the embryogenic tissue. The discussed T₁ and T₂ indicators can be utilized to characterize both the growth-related changes in an embryogenic tissue and the effect of biotic/abiotic stresses, thus potentially becoming a distinctive indicator of the state of any examined embryogenic tissue.