Ando Yuko, Nagata Shinji, Yanagisawa Schuichi, Yoneyama Tadakatsu
Department of Applied Biological Chemistry, The University of Tokyo, Yayoi 1-1-1, Bunkyo-Ku, Tokyo 113-8657, Japan.
Funct Plant Biol. 2012 Feb;40(1):89-100. doi: 10.1071/FP12158.
Copper (Cu) is an essential element for cereals, playing important roles as a cofactor of several enzymes. Copper and four other metals (Fe, Mn, Zn and Mo) taken up by roots are efficiently delivered to the shoots via xylem and phloem. Here we investigated the concentrations of Cu, Fe, Mn, Zn and Mo in the xylem and phloem saps as well as in tissues of rice (Oryza sativa L.) seedlings when they were grown under different Cu levels in culture solution. Although the Cu concentrations in the roots and the Mn concentrations in the mature shoot tissues were increased with the increase of the Cu level in the culture solution, the concentrations of Cu and the other four metals in the xylem and phloem saps and the Cu contents in the shoot tissues were only slightly affected by moderate increases in the Cu medium level. The results of our analyses using membrane filtration, size-exclusion chromatography and electrospray ionisation time-of-flight mass spectrometry indicate that Cu in the xylem sap is dominantly complexed by 2'-deoxymugineic acid, whereas Cu in the phloem sap is bound to several compounds, i.e. nicotianamine, histidine and other >3-kDa compounds.
铜（Cu）是谷物生长所必需的元素，作为多种酶的辅因子发挥着重要作用。根系吸收的铜以及其他四种金属（铁、锰、锌和钼）通过木质部和韧皮部有效地输送到地上部分。在此，我们研究了在培养液中不同铜水平下生长的水稻（Oryza sativa L.）幼苗的木质部和韧皮部汁液以及组织中铜、铁、锰、锌和钼的浓度。尽管随着培养液中铜水平的升高，根中的铜浓度以及成熟地上部组织中的锰浓度有所增加，但木质部和韧皮部汁液中铜及其他四种金属的浓度以及地上部组织中的铜含量仅受到铜培养基水平适度升高的轻微影响。我们使用膜过滤、尺寸排阻色谱和电喷雾电离飞行时间质谱分析的结果表明，木质部汁液中的铜主要与2'-脱氧 mugineic 酸络合，而韧皮部汁液中的铜则与几种化合物结合，即烟酰胺、组氨酸和其他分子量大于3 kDa的化合物。
