Bialek K, Cohen J D
Horticultural Crops Quality Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, Beltsville, Maryland 20705-2350.
Plant Physiol. 1992 Dec;100(4):2002-7. doi: 10.1104/pp.100.4.2002.
We have shown that amide-linked IAA (indole-3-acetic acid) conjugates accumulated to high levels during maturation of bean seeds (K. Bialek and J.D. Cohen [1989] Plant Physiol 91: 775-779). In the present study, we were interested in the fate of these and other IAA conjugates during seed germination. The content of amide-linked conjugates of IAA in cotyledons declined dramatically during the first hours of imbibition. The rate of decline slowed markedly during the period of the resumption of axis growth. The level of amide-linked IAA conjugates in cotyledons remained relatively high after almost 1 week of germination. The decline of IAA conjugates in cotyledons was followed by a steady increase in the content of both free and amide-linked IAA in the embryonic axes. Amide-linked IAA conjugates were also present in the axes cultured on agar after the cotyledons were removed, which suggests that de novo production of these IAA conjugates occurs in the axis of germinating bean seedlings. A comparison of relative amounts of free and conjugated IAA in the axes of intact seedlings and axes cultured on agar showed lower levels of free IAA and higher levels of conjugated IAA in much slower growing isolated axes. These results suggest a more general role for IAA conjugates in the control of seedling growth than simply to serve as a seed storage form of auxin.
我们已经表明，酰胺连接的吲哚 - 3 - 乙酸（IAA）共轭物在菜豆种子成熟过程中积累到很高水平（K. 比亚莱克和J.D. 科恩[1989]《植物生理学》91: 775 - 779）。在本研究中，我们关注这些及其他IAA共轭物在种子萌发过程中的去向。在吸胀的最初几个小时内，子叶中IAA的酰胺连接共轭物含量急剧下降。在胚轴生长恢复期间，下降速率明显减缓。在萌发近1周后，子叶中酰胺连接的IAA共轭物水平仍相对较高。子叶中IAA共轭物含量下降之后，胚轴中游离IAA和酰胺连接IAA的含量稳步增加。去除子叶后，在琼脂上培养的胚轴中也存在酰胺连接的IAA共轭物，这表明这些IAA共轭物在萌发的菜豆幼苗胚轴中会重新合成。对完整幼苗胚轴和在琼脂上培养的胚轴中游离IAA和共轭IAA相对含量的比较表明，在生长慢得多的分离胚轴中，游离IAA水平较低，共轭IAA水平较高。这些结果表明，IAA共轭物在控制幼苗生长中具有更广泛的作用，而不仅仅是作为生长素的种子储存形式。
