Synthesis of New Indolic Plant Hormones and Their Application to Plant Tissue Cultures

在前期从豌豆未成熟种子中分离出4-氯吲哚-乙酸及其甲酯的基础上，我们合成了吲哚-乙酸二氯衍生物的全部10个区域异构体，并测定了它们的生长素活性。其中，-二氯吲哚-乙酸(5，6-Cl2-IAA)的生长素活性最强，比已知的所有天然和合成的生长素都要强。它在绿豆幼苗中诱导出大量的侧根，并能抵抗过氧化物酶的分解。相反，5，7-二氯吲哚-乙酸(5，7-Cl2-IAA)的生长素活性明显弱于其他二氯吲哚衍生物。有趣的是，小麦和水稻种子用5，7-Cl2-IAA萌发时，根明显向上卷曲。这种负向地性显然是一种抗生长素活性。为了消除其弱的生长素活性，我们将AA的侧链从乙酰基改变为异丁酰基，这已知会改变2，4…的生长素活性More-D对PCIB的抗生长素作用。合成的α-(5，7-二氯吲哚-3-)异丁酸(5，7-Cl2-IIBA)对燕麦胚芽鞘生长素介导的伸长有抑制作用。其活性高于α-(对氯苯氧基)异丁酸，与典型的抗生长素2，3，5-三碘苯甲酸相当。5，6-Cl2-IAA以0.01 mg/L诱导杜鹃花根培养产生托烷生物碱，与0.5 mg/L IAA相当。利用5，6-Cl2-IAA，不仅在根组织中检测到生物碱，而且在基质中也检测到生物碱。以烟草花梗为外植体，在含有过量生长素(IAA)和抗生长素(5，7-Cl2-IIBA)的改良Murashige-Skoog培养基上建立了烟草花芽形成的生物测定体系。在这个系统中，5，7-Cl2-IIBA是非常有效的：短日照处理植株的叶片分泌物促进了花芽的形成。此外，产生的花蕾长成了大的、发育良好的花蕾，形状类似于完整烟草植株的自然花蕾。较少

Based on our success in the previous isolation of 4-chloroindole--acetic acid and its methyl ester from immature seeds of Pisum sativum, we synthesized all ten regioisomers of dichloro-derivatives of indole--acetic acid, and measured their auxin activity. Among them, -dichloroindole--acetic acid (5, 6-Cl_2-IAA) showed the strongest auxin activity, and this activity was stronger than all the known natural and synthetic auxins. It induced many lateral roots in mung bean seedlings, and resisted peroxi-dase-catalyzed decomposition. In contrast, 5, 7-dichloroindole--acetic acid (5, 7-Cl_2-IAA) showed much weaker auxin activity than the other dichloro-indole derivatives. Interestingly, when wheat and rice seeds were germinated with 5, 7-Cl_2-IAA their roots curled markedly upwards. This negative geotropism is clearly an antiauxin activity. To eliminate its weak auxinlike activity, we changed the side chain of AA from acetyl to isobutyryl group, which is known to change auxin activity of 2, 4 … More -D to antiauxin of PCIB. alpha-(5, 7-Dichloroindole-3-)isobutyric acid (5, 7-Cl_2-IIBA) thus synthesized showed to inhibit auxin-mediated elongation of avena coleoptiles. Its activity is stronger than that of alpha-(pchlorophenoxy)isobutyric acid and is comparable to that of 2, 3, 5-triiodobenzoic acid, which are typical antiauxins.5, 6-Cl_2-IAA induced tropane alkaloid production in root cultures of a Duboisia hybrid at 0.01mg/L, which was comparable to 0.5mg/L IAA. By using 5, 6-Cl_2-IAA, the alkaloids were detected not only in the root tissue but also in the medium. An in vitro bioassay system for floral bud formation was established using Nicotiana tabacum explants excised from floral stalks cultured on modified Murashige-Skoog medium containing excess auxin (IAA) and antiauxin (5, 7-Cl_2-IIBA). In this system, 5, 7-Cl_2-IIBA was very effective : leaf exudate from short day-treated plants stimulated floral bud formation. Moreover, the buds produced grew into large, well-developed ones with shapes similar to those of the natural floral buds of intact tobacco plants. Less