Identification of root hair inducing substance which was derived from shoot apex and analysis of the role of this substance in low pH induced root hair formatin.

在pH值为4的条件下培养莴苣幼苗，莴苣根部产生了高密度的根毛。在这一现象中，未知物质的供应是必不可少的，而未知物质应来自茎尖。本研究对该物质进行了鉴定和表征。首先，确定合适的植物材料。不仅幼苗中含有这种物质，年老的植物中也含有这种物质。因此，选择1个月龄的幼苗作为起始材料。其次，对提取方法进行了研究。丙酮浸提比水浸提效率高约30倍。为进行生物测定，构建了微型丙烯酸树脂培养器。热处理（100℃，10 mm）对丙酮提取物的活性没有影响。结果表明，该活性物质具有热稳定性。水-乙酸乙酯溶剂分馏结果表明，该物质为水相分馏。然后用C18预柱对溶剂分馏产物进行部分纯化。当该物质溶于pH6的水中时，该物质不能吸附在色谱柱上。溶解在pH3水中的物质可以吸附在柱上，用20%乙腈洗脱。采用阴离子交换前柱，可使该物质在酸性部分洗脱。这些结果表明，该物质应该是一周有机酸。C18柱高效液相色谱对酸性部分进行深入分离，发现该物质在18.5 ~ 21.5%乙腈部分的单峰处被分离。

High density of root hairs were induced on a lettuce root when a lettuce seedling was cultured at pH 4.In this phenomenon, supply of unknown substance which should be derived form shoot apex was essential.In this study, identification and characterization of this substance was performed.At first, proper plant materials were determined.Not only young seedling but also aged grown plant contained this substance.Therefore, 1 month old grown seedlings were chosen as a starting materials.Next, extraction methods were investigated. Acetone extraction was about 30 times eWcientx to compare with water extraction.For the bioassay, tiny acrylic resin culturing wares were constructed.Activity of acetone extracts was not influenced by heat treatment(100 C, 10 mm).This results ggested that the active substance was heat stable.Result of solvent fractionation using water-ethyl acetate indicated that the substance was fractionated in water phase.Next, resultant of solvent fractionation was partially purified by C18 pre-column.When the substance was solved in pH6 water, the substance could not be adsorbed on the column.The substance solved in pH3 water could be adsorbed on the column, and eluted by 20% acetonitrile.Using anion exchange pre-column, the substance could be eluted in the acidic fraction.These results suggested that the substance should be a week organic acid.Advanced isolation of the acidic fraction by C18 column HPLC exhibited that the substance was isolated in the single peak at 18.5-21.5% acetonitrile fraction.