ISHS Acta Horticulturae 1404: IV Asian Horticultural Congress - AHC2023
Structure and function of the xylem of tomato stem with adventitious roots |
| Authors: | T. Umebayashi, R. Araki, Y. Suzuki, K. Fukuda, H. Kanda, N. Kitamoto, H. Imanishi, Y. Yoshida |
| Keywords: | dye uptake method, micro-CT, vessel, water transport, xylem structure |
| DOI: | 10.17660/ActaHortic.2024.1404.30 |
| Abstract:
Adventitious roots (ARs) form on the stems of tomato plants (Solanum lycopersicum L.) under moist conditions. When cultured in hydroponic conditions, tomato plants with ARs display higher total water absorption, plant length, and total fruit weight compared to plants without ARs. Although the developmental processes of ARs in tomato stems have been studied, the physiological mechanisms of water absorption, including water-conducting pathways, require further investigation. In this study, high-resolution X-ray computed tomography (micro-CT) and the dye uptake method were used to visualize the structure and function of the xylem of AR-forming stems. Three-dimensional (3D) representations of the stems were developed based on micro-CT images of both frozen and air-dried tomato samples. The vessel distribution and regions connected to ARs were clearly observed in the 3D models of dried samples, however, not in those of frozen samples. The dye uptake method displayed that many conduits and fibers were stained on the cortical side, in addition the dye was detected in some inner conduits near the pith. Vessel distribution and diameter were readily observed on cryostat sections adhered to the plastic film, in addition the shredded and missing tissues were also observed. The CT analysis indicated that an AR consisted of multiple connections, and these connections were also observed in the inner xylem near the pith. Therefore, 3D analysis using micro-CT is necessary to understand the structure of ARs in the stem. Analyses using both CT and dye uptake facilitate a comprehensive visualization of water-conducting pathways in a stem with ARs. This study displays that the main pathways of water are the outer conduits and fibers on the cortical side, in addition water absorbed from ARs can be also supplied via inner conduits. | |
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