Burton R A, Gibeaut D M, Bacic A, Findlay K, Roberts K, Hamilton A, Baulcombe D C, Fincher G B
Department of Plant Science, University of Adelaide, South Australia, Australia.
Plant Cell. 2000 May;12(5):691-706. doi: 10.1105/tpc.12.5.691.
Specific cDNA fragments corresponding to putative cellulose synthase genes (CesA) were inserted into potato virus X vectors for functional analysis in Nicotiana benthamiana by using virus-induced gene silencing. Plants infected with one group of cDNAs had much shorter internode lengths, small leaves, and a "dwarf" phenotype. Consistent with a loss of cell wall cellulose, abnormally large and in many cases spherical cells ballooned from the undersurfaces of leaves, particularly in regions adjacent to vascular tissues. Linkage analyses of wall polysaccharides prepared from infected leaves revealed a 25% decrease in cellulose content. Transcript levels for at least one member of the CesA cellulose synthase gene family were lower in infected plants. The decrease in cellulose content in cell walls was offset by an increase in homogalacturonan, in which the degree of esterification of carboxyl groups decreased from approximately 50 to approximately 33%. The results suggest that feedback loops interconnect the cellular machinery controlling cellulose and pectin biosynthesis. On the basis of the phenotypic features of the infected plants, changes in wall composition, and the reduced abundance of CesA mRNA, we concluded that the cDNA fragments silenced one or more cellulose synthase genes.
将对应于假定纤维素合酶基因（CesA）的特定cDNA片段插入马铃薯X病毒载体中，通过病毒诱导的基因沉默在本氏烟草中进行功能分析。感染一组cDNA的植物节间长度明显缩短，叶片变小，呈现“矮化”表型。与细胞壁纤维素缺失一致，异常大且在许多情况下呈球形的细胞从叶片下表面鼓起，尤其是在靠近维管组织的区域。对感染叶片制备的细胞壁多糖进行连锁分析表明，纤维素含量降低了25%。感染植物中CesA纤维素合酶基因家族至少一个成员的转录水平较低。细胞壁中纤维素含量的降低被同型半乳糖醛酸的增加所抵消，其中羧基的酯化程度从约50%降至约33%。结果表明，反馈环将控制纤维素和果胶生物合成的细胞机制相互连接起来。根据感染植物的表型特征、细胞壁组成的变化以及CesA mRNA丰度的降低，我们得出结论，cDNA片段使一个或多个纤维素合酶基因沉默。
