Department of Botany, University of Wisconsin, 53706, Madison, WI.
Planta. 1983 Jul;157(4):289-97. doi: 10.1007/BF00397399.
The oxidation of carbohydrate by the pentose-phosphate pathway in the shoot apical meristem and developing leaf primordia of Dianthus chinensis was assessed by measuring the activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49). On a kg(-1) dry weight h(-1) basis, activity rose from 250 mmol in the apical meristem to 550 mmol in the first two leaf primordia and then declined to 350 mmol in the sixth pair of leaf primordia, and finally to 200 mmol in leaves just emerged from the shoot bud. Measurements of activity in the sixth leaf pair from the apex showed differential distribution in leaf tissues. Epidermal and mesophyll tissue had about the same activity as whole-leaf tissue, but vascular bundles had 70% greater activity. Within the vascular tissue, activity in the phloem was twice as high as in the xylem. When activity was expressed on a per-cell basis, there was a continuous increase from 20 fmol in the apex to 2 pmol in the sixth leaf pair. Activity on a per unit cell volume basis showed that cells of the apical meristem and the epidermis, mesophyll and xylem of the sixth leaf pair had similar values, about 30 amol; only the two youngest pairs of primordia and the phloem had values two or three times this amount.
通过测量葡萄糖-6-磷酸脱氢酶（EC 1.1.1.49）的活性，评估了香石竹茎尖分生组织和发育中的叶片原基中戊糖磷酸途径对碳水化合物的氧化作用。以每千克干重每小时为基础，活性从顶端分生组织的 250mmol 上升到前两个叶片原基的 550mmol，然后下降到第六对叶片原基的 350mmol，最后在刚从芽中长出的叶片中下降到 200mmol。从顶端测量第六对叶片的活性显示出叶片组织中的差异分布。表皮和叶肉组织的活性与整个叶片组织大致相同，但维管束的活性高 70%。在维管组织中，韧皮部的活性是木质部的两倍。当以每细胞为基础表达活性时，从顶端的 20fmol 连续增加到第六对叶片的 2pmol。以单位细胞体积为基础的活性表明，顶端分生组织和表皮、叶肉和木质部的细胞具有相似的数值，约为 30amol；只有最年轻的两对原基和韧皮部的数值是这个数量的两倍或三倍。
