Factors for the formation of deep-root-system that improves the drought resistance in the view of cell elongation and cell-wall expansibility

从细胞伸长和细胞壁扩张性角度探讨提高抗旱性的深根系形成因素

• 批准号: 12460008
• 负责人: ABE Jun
• 金额: $ 5.76万
• 依托单位: THE UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12460008/
• 关键词: Cell elongation; Drought resistanse; Rice (Oryza sativa L); Root; Water stress; Direction of root elongation; トウモロコシ

In this study, we first established the method using maize plants to investigate the relationships between the elongation of seminal roots and cell elongation and cell division under different water conditions. Not the low osmotic potential as pseudo-drought stress but the real drought stress using autoclaved vermiculite was treated on seedlings. Closs sections of the apical part of the seminal roots were made by a freezing microsilcer and observed by a fluorescent microscope to measure the cell length of the cortex cells. The cell length of cortex cells in the apical 5cm of seminal roots in rice cultivars with different drought resistance was measured with this method. The drought resistant varieties showed remarkable increase of cell length in the root elongation zone under low water content of the medium, suggesting the close relation of the cell elongation pattern in the elongation zone to the varietal differences in root elongation and the root response to the drought. The cell wall thickness in roots (in particular, in endodermis) was large in drought resistant varieties. The final cell length, however, did not showed difference among the varieties, suggesting the large contribution of the cell division in root apex and the root growth angle in the determination of the vertical distribution of roots. The observation of the root caps of maize plants indicated that the root growth angle gets closer to vertical with the longitudinal development of columella tissue and the enlargement of amyloplasts. Varietal difference in the accumulation of silicon on the cell wall of the root endodermis was also investigated in relation to the drought resistance.

本研究首次建立了不同水分条件下玉米种子根伸长与细胞伸长和细胞分裂的关系。用蒸压蛭石处理幼苗，模拟真实的干旱胁迫，而不是模拟低渗透势干旱胁迫。用冷冻显微镜制作精根顶端的闭合切片，在荧光显微镜下观察皮层细胞的长度。用该方法测定了不同抗旱性水稻品种种子根顶端5cm皮层细胞的细胞长度。抗旱品种在低含水量条件下，根伸长区细胞长度显著增加，表明伸长区细胞伸长模式与品种间根伸长差异及根系对干旱的反应密切相关。抗旱品种根的细胞壁（尤其是内皮层）厚度大。但最终细胞长度在品种间差异不显著，表明根尖细胞分裂和根生长角在决定根的垂直分布方面有较大贡献。对玉米根冠的观察表明，随着根柱组织的纵向发育和造粉体的增大，根的生长角度逐渐向垂直方向靠拢。同时还研究了硅在根内皮层细胞壁上积累的品种差异与抗旱性的关系。