LEAF ABSCISSION IN IMPATIENS (BALSAMINACEAE) IS DUE TO LOSS OF HIGHLY DE-ESTERIFIED HOMOGALACTURONANS IN THE MIDDLE LAMELLAE
LEAF ABSCISSION IN IMPATIENS (BALSAMINACEAE) IS DUE TO LOSS OF HIGHLY DE-ESTERIFIED HOMOGALACTURONANS IN THE MIDDLE LAMELLAE
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DOI：
10.3732/ajb.1000268
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发表时间：
2011-04-01
影响因子：
3
通讯作者：
Vaughn, Kevin C.
中科院分区：
文献类型：
--
作者：
Bowling, Andrew J.;Vaughn, Kevin C.
研究目的：脱落区（AZ）是叶子和其他器官脱落的地方。由于AZ的体积小，并且周围组织不参与分解，因此通过经典的生物化学技术研究AZ是困难的。本研究的目的是确定AZ细胞壁是否在化学上与叶柄的其他细胞不同，这可能使它们在水解过程中更容易被酶降解，并确定哪些细胞壁多糖在水解过程中被降解。一组识别大量细胞壁多糖和糖蛋白表位的抗体用于探测凤仙花叶AZ的切片，关键结果：在解离之前，发现AZ细胞的壁在组成上与AZ近端和远端的细胞的壁相似。在监测的所有表位中，仅发现中间层的高度去酯化的同型半乳糖醛酸（HG）在解离后且仅在分离平面处减少。更高度酯化的同型半乳糖醛酸以及其他果胶和木葡聚糖表位不受影响。此外，纤维素，检测到的内切葡聚糖酶-金探针和纤维素结合模块染色，是不受影响的，即使在面对分离situ.Conclusions的细胞的墙壁上：在凤仙花的叶dispensation区，在dispensation过程中的壁改变严格限制在分离的平面，只涉及损失的高度去酯化果胶从中间laminae。
Premise of study: Abscission zones (AZ) are sites where leaves and other organs are shed. Investigating the AZ by classical biochemical techniques is difficult due to its small size and because the surrounding tissue is not involved in abscission. The goals of this study were to determine whether AZ cell walls are chemically unique from the other cells of the petiole, perhaps making them more susceptible to enzymatic degradation during abscission and to identify which cell wall polysaccharides are degraded during abscission.Methods: A battery of antibodies that recognize a large number of cell wall polysaccharide and glycoprotein epitopes was used to probe sections of the Impatiens leaf AZ at several time points in the abscission process.Key results: Prior to abscission, the walls of the AZ cells were found to be similar in composition to the walls of the cells both proximal and distal to the AZ. Of all the epitopes monitored, only the highly de-esterified homogalacturonans (HG) of the middle lamellae were found to be reduced post-abscission and only at the plane of separation. More highly esterified homogalacturonans, as well as other pectin and xyloglucan epitopes were not affected. Furthermore, cellulose, as detected by an endoglucanase-gold probe and cellulose-binding module staining, was unaffected, even on the walls of the cells facing the separation site.Conclusions: In the leaf abscission zone of Impatiens, wall alterations during abscission are strictly limited to the plane of separation and involve only the loss of highly de-esterified pectins from the middle lamellae.