Davidonis G H, Hamilton R H, Mumma R O
Pesticide Research Laboratory and Graduate Study Center and Departments of Entomology and Biology, The Pennsylvania State University, University Park, Pennsylvania 16802.
Plant Physiol. 1978 Jul;62(1):80-3. doi: 10.1104/pp.62.1.80.
The metabolism of [1-(14)C]2,4-dichlorophenoxyacetic acid (2,4-D) in soybean (Glycine max [L.] Merrill var. Amsoy) root callus and in differentiated soybean root cultures was investigated as a function of pesticide concentration and age of tissue. The chronological age of the tissue was found to be correlated with the mitotic index which reached a peak at 2 weeks and then declined. The metabolism of 2,4-D changed with age of the root callus tissue. The amount of free 2,4-D found in 3-week-old root callus tissue rapidly increased as the concentration of 2,4-D in the medium was increased from 10(-6) to 10(-5) molar, whereas the low level of aqueous (glycosides) and ether soluble metabolites (2,4-D amino acid conjugates) increased slowly. With 9-week-old root callus tissue, the amount of free 2,4-D remained at a relatively low, constant level (saturation level) as the concentration of 2,4-D in the medium increased. Under these conditions the aqueous metabolites increased only slightly but the ether fraction (2,4-D amino acid conjugates) rapidly increased. Thus, the older root callus tissue appeared to regulate the level of free 2,4-D at about 4 nanomoles per gram by converting any excess 2,4-D into amino acid conjugates.In 3-week-old, differentiated root cultures the metabolism of 2,4-D closely paralleled the metabolism found in the older 9-week-old callus tissue. The saturation level of free 2,4-D found in this tissue was only about 1 to 2 nanomoles per gram.
研究了[1-(14)C]2,4-二氯苯氧乙酸（2,4-D）在大豆（Glycine max [L.] Merrill var. Amsoy）根愈伤组织和分化的大豆根培养物中的代谢情况，该代谢情况是农药浓度和组织年龄的函数。发现组织的实足年龄与有丝分裂指数相关，有丝分裂指数在2周时达到峰值，然后下降。2,4-D的代谢随根愈伤组织年龄的变化而变化。当培养基中2,4-D的浓度从10^(-6)摩尔增加到10^(-5)摩尔时，3周龄根愈伤组织中游离2,4-D的量迅速增加，而水溶性（糖苷）和醚溶性代谢物（2,4-D氨基酸结合物）的低水平则缓慢增加。对于9周龄的根愈伤组织，随着培养基中2,4-D浓度的增加，游离2,4-D的量保持在相对较低的恒定水平（饱和水平）。在这些条件下，水溶性代谢物仅略有增加，但醚部分（2,4-D氨基酸结合物）迅速增加。因此，较老的根愈伤组织似乎通过将任何过量的2,4-D转化为氨基酸结合物，将游离2,4-D的水平调节在约每克4纳摩尔。在3周龄的分化根培养物中，2,4-D的代谢与在较老的9周龄愈伤组织中发现的代谢情况非常相似。在该组织中发现的游离2,4-D的饱和水平仅约为每克1至2纳摩尔。
