Mélida Hugo, García-Angulo Penélope, Alonso-Simón Ana, Encina Antonio, Alvarez Jesús, Acebes José Luis
Area de Fisiología Vegetal, Facultad de CC., Biológicas y Ambientales, Universidad de León, 24071, León, Spain.
Planta. 2009 Feb;229(3):617-31. doi: 10.1007/s00425-008-0860-8. Epub 2008 Dec 2.
Growth of maize (Zea mays L.) callus-culture cells was inhibited using dichlobenil (2,6 dichlorobenzonitrile, DCB) concentrations > or =1 microM; I (50) value for the effect on inhibited fresh weight gain was 1.5 microM. By increasing the DCB concentration in the culture medium, DCB-habituated cells became 13 times more tolerant of the inhibitor (I (50): 20 microM). In comparison with non-habituated calluses, DCB-habituated calluses grew slower, were less friable and were formed by irregularly shaped cells surrounded by a thicker cell wall. By using an extensive array of techniques, changes in type II cell wall composition and structure associated with DCB habituation were studied. Walls from DCB-habituated cells showed a reduction of up to 75% in cellulose content, which was compensated for by a net increase in arabinoxylan content. Arabinoxylans also showed a reduction in their extractability and a marked increase in their relative molecular mass. DCB habituation also involved a shift from ferulate to coumarate-rich cells walls, and enrichment in cell wall esterified hydroxycinnamates and dehydroferulates. The content of polymers such as mixed-glucan, xyloglucan, mannans, pectins or proteins did not vary or was reduced. These results prove that the architecture of type II cell walls is able to compensate for deficiencies in cellulose content with a more extensive and phenolic cross-linked network of arabinoxylans, without necessitating beta-glucan or other polymer enhancement. As a consequence of this modified architecture, walls from DCB-habituated cells showed a reduction in their swelling capacity and an increase both in pore size and in resistance to polysaccharide hydrolytic enzymes.
当二氯苯腈（2,6 - 二氯苯腈，DCB）浓度≥1微摩尔时，玉米（Zea mays L.）愈伤组织培养细胞的生长受到抑制；对鲜重增加抑制作用的半数抑制浓度（I(50)）值为1.5微摩尔。通过提高培养基中DCB的浓度，适应DCB的细胞对该抑制剂的耐受性提高了13倍（I(50)：20微摩尔）。与未适应的愈伤组织相比，适应DCB的愈伤组织生长较慢，质地较硬，由形状不规则且被较厚细胞壁包围的细胞形成。通过使用一系列广泛的技术，研究了与DCB适应相关的II型细胞壁组成和结构的变化。适应DCB的细胞的细胞壁纤维素含量降低了多达75%，这由阿拉伯木聚糖含量的净增加得到补偿。阿拉伯木聚糖的可提取性也降低了，其相对分子质量显著增加。DCB适应还涉及细胞壁从富含阿魏酸向富含香豆酸的转变，以及细胞壁酯化羟基肉桂酸和脱氢阿魏酸的富集。混合葡聚糖、木葡聚糖、甘露聚糖、果胶或蛋白质等聚合物的含量没有变化或有所降低。这些结果证明，II型细胞壁的结构能够通过更广泛的阿拉伯木聚糖酚类交联网络来弥补纤维素含量的不足，而无需增强β - 葡聚糖或其他聚合物。由于这种结构的改变，适应DCB的细胞的细胞壁膨胀能力降低，孔径和对多糖水解酶的抗性增加。
