ROOT-NODULES OF PHASEOLUS - EFFICIENT SCAVENGERS OF MOLYBDENUM FOR N2-FIXATION
ROOT-NODULES OF PHASEOLUS - EFFICIENT SCAVENGERS OF MOLYBDENUM FOR N2-FIXATION
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DOI：
10.1093/jxb/42.5.679
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发表时间：
1991-05-01
影响因子：
6.9
通讯作者：
GILLER, KE
中科院分区：
文献类型：
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作者：
BRODRICK, SJ;GILLER, KE
钼被认为在韧皮部具有中等流动性，这可能通过限制钼对豆科植物根瘤的供应来限制氮的固定。在不给钼的情况下，即使籽粒钼含量很高，其钼含量也会以牺牲芽和根为代价而增加。从在进料液中接受钼的植物中取样的根瘤的浓度为21-78 mu-g Mo g-1。在缺钼和种子含量不足（Mo -1 < 0.5 mu-g）的情况下，小种子型的结核浓度为1.9 ~ 3.5 mu-g Mo -1，大种子型的结核浓度为8.7 +/- 0.48 mu-g Mo -1。这些植物对氮的固定没有受到损害，除了一个根瘤浓度为1.9 mu-g Mo -1的实例。通过叶面处理，钼能有效地从叶片转移到根和根瘤。施用于叶片的3.3 mu-g钼在10 d后全部在植株中恢复，根瘤中钼含量增加81%，芽中钼含量增加56%。根系Mo含量比未进行叶面钼处理的植株高8倍。当钼在植株中缺乏时，钼是流动的，从根和芽向根瘤转运。因此，即使植物完全依赖少量的钼种子储备，根瘤的钼浓度和含量也经常维持在足以固定n2的水平。
Molybdenum is thought to be of intermediate mobility in the phloem and this may limit N2-fixation by restricting the supply of molybdenum to the nodules of legumes.When no molybdenum was supplied to Phaseolus vulgaris nodule Mo content increased at the expense of shoots and roots even when seed molybdenum content was large. Nodules sampled from plants receiving molybdenum in the feeding solution had a concentration of 21-78-mu-g Mo g-1. In the absence of molybdenum and with deficient seed content (< 0.5-mu-g Mo seed-1) nodule concentrations ranged from 1.9 to 3.5-mu-g Mo g-1 in a small seeded genotype and 8.7 +/- 0.48-mu-g Mo g-1 in a large seeded genotype. N2-fixation in these plants was not impaired except in one instance where nodule concentration was 1.9-mu-g Mo g-1. Evidence that molybdenum is effectively translocated from leaves to roots and nodules was obtained using foliar treatments. All of the 3.3-mu-g Mo applied to a leaf was recovered in the plant after 10 d. Mo content of the nodules increased by 81%, whilst Mo content of shoots increased by 56%. Root Mo content was eight times greater than that in plants not receiving a foliar treatment of molybdenum.We conclude that when molybdenum was scarce in the plant it was mobile and was translocated from roots and shoots to the nodules. As a result, nodule concentrations and contents of molybdenum were frequently maintained at amounts sufficient for N2-fixation even when the plant was entirely dependent on a small seed reserve of molybdenum.