Keski-Saari Sarita, Julkunen-Tiitto Riitta
Natural Product Research Laboratories, Department of Biology, University of Joensuu, P.O.Box 111, FIN-80101 Joensuu, Finland.
Physiol Plant. 2003 May;118(1):114-126. doi: 10.1034/j.1399-3054.2003.00077.x.
The composition and concentrations of phenolic compounds were studied in the first true leaves, cotyledons, stems and roots of 2.5-week-old seedlings of mountain birch (Betula pubescens ssp. czerepanovii). The differences in secondary compounds among these plant parts were both qualitative and quantitative. In all parts, condensed tannins accounted for more than 50% of the phenolics. In the first true leaves and cotyledons, chlorogenic acid was the most abundant of the HPLC phenolics. The main components in stems were (+)-catechins and rhododendrins whereas in roots, the main components were ellagitannins. The seedlings were grown at three levels of nitrogen supply (very low-N, low-N, moderate-N), and the effect of nitrogen on concentrations of phenolic compounds was studied in all plant parts. The dry weight of all plant parts, except the roots, increased with increased nitrogen. In all parts, the concentration of condensed tannins was higher at lower levels of nitrogen than at moderate-N. The concentrations of total HPLC phenolics and also those of the compound groups of HPLC phenolics were, however, affected only in the first true leaves and roots. The concentrations in the first true leaves were generally higher in seedlings grown at very low-N and low-N than in seedlings grown at moderate-N. The concentrations in roots were highest at low-N. Not all compounds responded to nitrogen supply in the same manner. The changes in concentrations cannot be exclusively interpreted as changes in the accumulation of phenolic compounds, due to dilution caused by the increase in biomass in better nitrogen availability. There were differences in carbon allocation between condensed tannins and HPLC phenolics in seedlings grown at different nitrogen levels.
对2.5周龄的欧洲山桦（Betula pubescens ssp. czerepanovii）幼苗的第一片真叶、子叶、茎和根中的酚类化合物组成及浓度进行了研究。这些植物部位中次生化合物的差异既有定性的也有定量的。在所有部位，缩合单宁占酚类化合物的比例超过50%。在第一片真叶和子叶中，绿原酸是高效液相色谱法测定的酚类化合物中含量最高的。茎中的主要成分是（+）-儿茶素和杜鹃素，而根中的主要成分是鞣花单宁。幼苗在三种氮供应水平（极低氮、低氮、中等氮）下生长，并研究了氮对所有植物部位酚类化合物浓度的影响。除根外，所有植物部位的干重都随着氮含量的增加而增加。在所有部位，低氮水平下缩合单宁的浓度高于中等氮水平。然而，高效液相色谱法测定的总酚类化合物浓度以及酚类化合物组的浓度仅在第一片真叶和根中受到影响。在极低氮和低氮条件下生长的幼苗，其第一片真叶中的浓度通常高于在中等氮条件下生长的幼苗。根中的浓度在低氮时最高。并非所有化合物对氮供应的反应方式都相同。由于在氮供应较好时生物量增加导致稀释，浓度变化不能完全解释为酚类化合物积累的变化。在不同氮水平下生长的幼苗中，缩合单宁和高效液相色谱法测定的酚类化合物之间的碳分配存在差异。
