Department of Botany, Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel.
Plant Physiol. 1992 Sep;100(1):120-30. doi: 10.1104/pp.100.1.120.
Our previous work (E. Shedletzky, M. Shmuel, D.P. Delmer, D.T.A. Lamport [1990] Plant Physiol 94:980-987) showed that suspension-cultured tomato cells adapted to growth on the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile (DCB) have a markedly altered cell wall composition, most notably a markedly reduced level of the cellulose-xyloglucan network. This study compares the adaptation to DCB of two cell lines from dicots (tomato [Lycopersicon esculentum] and tobacco [Nicotiana tabacum]) and a Graminaceous monocot (barley [Hordeum bulbosum] endosperm). The difference in wall structures between the dicots and the monocot is reflected in the very different types of wall modifications induced by growth on DCB. The dicots, having reduced levels of cellulose and xyloglucan, possess walls the major integrity of which is provided by Ca(2+)-bridged pectates because protoplasts can be prepared from these cells simply by treatment with divalent cation chelator and a purified endopolygalacturonase. The tensile strength of these walls is considerably less than walls from nonadapted cells, but wall porosity is not altered. In contrast, walls from adapted barley cells contain very little pectic material and normal to elevated levels of noncellulosic polysaccharides compared with walls from nonadapted cells. Surprisingly, they have tensile strengths higher than their nonadapted counterpart, although cellulose levels are reduced by 70%. Evidence is presented that these walls obtain their additional strength by an altered pattern of cross-linking of polymers involving phenolic components. Such cross-linking may also explain the observation that the porosity of these walls is also considerably reduced. Cells of adapted lines of both the dicots and barley are resistant to plasmolysis, suggesting that they possess very strong connections between the wall and the plasma membrane.
我们之前的工作（E. Shedletzky、M. Shmuel、D.P. Delmer、D.T.A. Lamport [1990] Plant Physiol 94:980-987）表明，适应于纤维素合成抑制剂 2,6-二氯苯腈（DCB）生长的悬浮培养番茄细胞具有明显改变的细胞壁组成，最显著的是纤维素-木葡聚糖网络的水平明显降低。这项研究比较了两种双子叶植物（番茄[Lycopersicon esculentum]和烟草[Nicotiana tabacum]）和一种单子叶植物（大麦[Hordeum bulbosum]胚乳）的细胞系对 DCB 的适应。双子叶植物和单子叶植物的细胞壁结构差异反映在生长在 DCB 上诱导的细胞壁修饰类型非常不同。双子叶植物的纤维素和木葡聚糖水平降低，其细胞壁的主要完整性由 Ca(2+)-桥接的果胶提供，因为可以通过用二价阳离子螯合剂和纯化的内切多聚半乳糖醛酸酶处理这些细胞来制备原生质体。这些细胞壁的拉伸强度明显小于未适应细胞的细胞壁，但细胞壁的孔隙率没有改变。相比之下，适应的大麦细胞壁中含有很少的果胶物质和正常到升高水平的非纤维素多糖，与未适应细胞的细胞壁相比。令人惊讶的是，尽管纤维素水平降低了 70%，但它们的拉伸强度高于其未适应的对应物。有证据表明，这些细胞壁通过涉及酚类成分的聚合物交联模式的改变获得了额外的强度。这种交联也可能解释了这样一个观察结果，即这些细胞壁的孔隙率也大大降低。适应的双子叶植物和大麦细胞系的细胞对质壁分离具有抗性，这表明它们在细胞壁和质膜之间具有非常强的连接。
