Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
Plant Physiol. 1990 Aug;93(4):1295-302. doi: 10.1104/pp.93.4.1295.
Free and conjugated indole-3-acetic acid (IAA) were measured by quantitative gas chromatography-selected ion monitoringmass spectrometry in the extraxylary region of the stem of large Pinus sylvestris (L.) trees during the annual cycle of cambial activity and dormancy. The extraxylary region at the stem top and bottom was divided into 3 and 4 fractions, respectively, for the free IAA measurements, while the entire extraxylary region was extracted when the IAA-conjugates were analyzed. The effect on the distribution pattern of expressing IAA level as a concentration (per gram fresh weight or dry weight) and as total amount (per square centimeter) was examined. The IAA level was much higher in the cambial region than in the fractions that contained the nonfunctional phloem and the periderm. The largest IAA concentration occurred in the fraction that included the cambium, whereas the total amount of IAA was greatest in the phloemcontaining fraction. The significance of the nonuniform radial distribution of IAA for estimating the IAA concentration in the cambial region is discussed in relation to how the cambial region is sampled. A slight Iongitudinal gradient in IAA concentration, decreasing from the top to the bottom of the stem, was observed in the cambial region when the cambium was in the grand period of activity, but not at the end of the cambial growing period. In all fractions, the total amount of IAA was highest when the cambium was active. However, the IAA concentration in the cambial region did not follow the same pattern, actually being lowest during the tracheid production period at the stem bottom. IAA conjugates were detected on all sampling dates except June 23, but their concentrations were always less than 14% of that of free IAA, and their occurrence did not obviously vary during the year. In general, there was a higher concentration of ester conjugates than of amide conjugates, and the ester conjugates were more abundant at the top of the stem than at the bottom.
在大径木欧洲云杉（L.）茎干形成层活动和休眠的年周期中，通过定量气相色谱-选择离子监测质谱法测量了茎外区游离和结合态吲哚-3-乙酸（IAA）。茎顶和茎底的茎外区分别分为 3 个和 4 个部分，用于游离 IAA 的测量，而在分析 IAA 结合物时提取整个茎外区。检查了表达 IAA 水平（每克鲜重或干重）和总量（每平方厘米）的浓度分布模式的影响。在形成层区的 IAA 水平远高于包含无功能韧皮部和周皮的部分。最大的 IAA 浓度出现在包含形成层的部分，而 IAA 的总量在包含韧皮部的部分最大。形成层区 IAA 非均匀径向分布对估计形成层区 IAA 浓度的意义，与形成层区取样方式有关。在形成层处于旺盛生长期时，在形成层区观察到从顶部到底部 IAA 浓度略有纵向梯度下降，但在形成层生长末期则没有。在所有部分中，当形成层活跃时，IAA 的总量最高。然而，形成层区的 IAA 浓度并未遵循相同的模式，实际上在茎底的管胞形成期最低。除 6 月 23 日外，所有采样日期均检测到 IAA 结合物，但它们的浓度始终低于游离 IAA 的 14%，且其全年的发生情况并未明显变化。通常，酯结合物的浓度高于酰胺结合物，并且在茎的顶部比在底部更丰富。
