The growth and phosphorus utilisation of plants in sterile media when supplied with inositol hexaphosphate, glucose 1-phosphate or inorganic phosphate
The growth and phosphorus utilisation of plants in sterile media when supplied with inositol hexaphosphate, glucose 1-phosphate or inorganic phosphate
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DOI：
10.1023/a:1004782324030
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发表时间：
2000-01-01
期刊：
影响因子：
4.9
通讯作者：
Richardson, AE
中科院分区：
文献类型：
--
作者：
Hayes, JE;Simpson, RJ;Richardson, AE
六种温带牧场物种（三种禾本科植物和三种豆科植物）的幼苗在无菌琼脂或沙蛭石培养基中，在无机磷酸盐 (P(i))、葡萄糖 1-磷酸盐 (G1P) 或肌醇六磷酸盐 (IHP) 存在下生长 19-24 天。琼脂 (pH 5.0) 的 IHP 吸附能力较低，而 IHP 几乎完全吸附在沙蛭石中。 P(i) 和 G1P 在两种媒体中都相对可用。测量每个物种的生长与磷 (P) 供应的关系，并确定芽产量达到最大产量 (P(crit)) 90% 时的 P(i) 供应水平。豆科植物的 P（临界）值通常高于禾本科植物，并且在沙蛭石中生长的三叶草幼苗相对于琼脂的 P（临界）值高六倍。当提供 G1P 时，六个物种的幼苗和提供 P(i) 的植物一样生长。相比之下，即使在琼脂中提供的磷水平比 P(crit) 高 40 倍，IHP 也是植物生长的不良磷来源。利用 T. subterraneum 在 IHP 存在下的生长情况，计算出在 20 天的生长过程中，根每天释放约 0.09 nkat 植酸酶 g(-1) 根干重。通过用来自黑曲霉的植酸酶（E.C. 3.1.3.8；0.012 nkat 植物(-1)，或类似于 1.3 nkat g(-1) 根干重）补充含有 IHP 的琼脂，可以获得足够的 P，使 T. subterraneum 幼苗能够与提供 P(i) 的植物一样生长。这些结果表明，虽然牧草植物可以非常有效地利用某些有机磷源（例如 G1P）中的磷，但植酸磷的获取受到底物可用性和植物根部水解可用 IHP 的能力的限制。
Seedlings of six temperate pasture species, three grasses and three legumes, were grown for 19-24 days in sterile agar or sand-vermiculite media, in the presence of inorganic phosphate (P(i)), glucose 1-phosphate (G1P) or inositol hexaphosphate (IHP). Agar (pH 5.0) had a low IHP-sorbing capacity while IHP was almost completely sorbed in sand-vermiculite. P(i) and G1P were relatively available in both media. Growth of each species was measured in relation to phosphorus (P) supply and levels of P(i) supply at which shoot yields reached 90% of maximum yield (P(crit)) were determined. P(crit) values were generally higher for the legume species than for the grasses, and were six-fold higher for Trifolium subterraneum L. seedlings when grown in sand-vermiculite relative to agar. When supplied with G1P, seedlings of the six species grew as well as plants supplied with P(i). By contrast, IHP was a poor source of P for plant growth, even when supplied in agar at levels up to 40-fold greater than P(crit). Using the growth of T. subterraneum in the presence of IHP, it was calculated that roots released approximately 0.09 nkat phytase g(-1) root dry wt per day, over 20 days of growth. By supplementing agar containing IHP with phytase from Aspergillus niger (E.C. 3.1.3.8; 0.012 nkat plant(-1), or similar to 1.3 nkat g(-1) root dry wt), sufficient P became available to enable T. subterraneum seedlings to grow as well as P(i)-supplied plants. These results indicate that while pasture plants can quite effectively use P from some organic P sources (e.g. G1P), the acquisition of phytate-P is limited both by availability of substrate and the capacity of plant roots to hydrolyse available IHP.