XYLOGLUCAN ENDOTRANSGLYCOSYLASE ACTIVITY, MICROFIBRIL ORIENTATION AND THE PROFILES OF CELL-WALL PROPERTIES ALONG GROWING REGIONS OF MAIZE ROOTS
XYLOGLUCAN ENDOTRANSGLYCOSYLASE ACTIVITY, MICROFIBRIL ORIENTATION AND THE PROFILES OF CELL-WALL PROPERTIES ALONG GROWING REGIONS OF MAIZE ROOTS
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DOI：
10.1093/jxb/44.8.1281
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发表时间：
1993-08-01
影响因子：
6.9
通讯作者：
TOMOS, AD
中科院分区：
文献类型：
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作者：
PRITCHARD, J;HETHERINGTON, PR;TOMOS, AD
对水培玉米幼苗根系膨大区进行了一系列理化分析。局部相对元素生长率和膨压的纵向分布表明，细胞壁在根尖5 mm处开始变松，在根尖5 ~ 10 mm处开始变紧。在200 mol m-3甘露醇（0.48 MPa）渗透胁迫下，根系快速均匀地降低了整个生长区域的膨胀压力。根尖5 ~ 1 ~ 0 mm区域的生长受抑制程度大于根尖区域。这表明根尖的管壁迅速松动，但在较基部的区域没有。在400 mol m-3甘露醇（渗透应力0.96 MPa）中浸泡24 h后，膨胀恢复到应力前的值。在这种应力处理下，尽管生长恢复，但在根尖4 ~ 10 mm区域生长减少，表明管壁收紧。在根端，与对照组织相比，局部元素相对生长率没有变化，表明这里的壁特性与对照值相似。在未受胁迫和受胁迫的根的生长剖面上，皮层细胞壁内表面的纤维素微原纤维越来越平行于根轴。渗透胁迫24 h后，根系的取向与未受胁迫的根尖区管壁松动和距根尖5 ~ 10 mm处管壁收紧没有相关性。可能的壁松动酶木葡聚糖内转糖基化酶（XET）的纵向分布与发育过程中壁松动的增加有很好的对应关系。在渗透胁迫后的管壁收紧区，单位干重XET活性降低（与未胁迫对照相比），但单位鲜重XET活性没有降低。
A series of physical and chemical analyses were made on the expanding zone of maize seedling roots grown in hydroponics. Comparison of longitudinal profiles of local relative elemental growth rate and turgor pressure indicated that cell walls become looser in the apical 5 mm and then tighten 5- 1 0 mm from the root tip. Immersion of roots in 200 mol m-3 mannitol (an osmotic stress of 0.48 MPa) rapidly and evenly reduced turgor pressure along the whole growing region. Growth was reduced to a greater extent in the region 5-1 0 mm from the root tip than in the apical region. This indicated rapid wall-loosening in the root tip, but not in the more basal regions.Following 24 h immersion in 400 mol m-3 mannitol (an osmotic stress of 0.96 MPa) turgor had recovered to pre-stressed values. Under this stress treatment, growth was reduced in the region 4- 1 0 mm from the root tip, despite the recovery of turgor, indicating a tightening of the wall. In the root apex, local relative elemental growth rate was unchanged in comparison to control tissue, showing that wall properties here were similar to the control values.Cellulose microfibrils on the inner face of cortical cell walls became increasingly more parallel to the root axis along the growth profile of both unstressed and stressed roots. Orientation did not correlate with the wall loosening in the apical region of unstressed roots, or with the tightening in the region 5-10 mm from the root tip following 24 h of osmotic stress.Longitudinal profiles of the possible wall-loosening enzyme xyloglucan endotransglycosylase (XET) had good correspondence with an increase in wall loosening during development. In the zone of wall tightening following osmotic stress, XET activity was decreased per unit dry weight (compared with the unstressed control), but not per unit fresh weight.