SCREENING OF PLANT GROWTH REGULATORS FROM INTERMEDIATES OF PLANT PIGMENT BIOSYNTHESIS

叶绿素和类胡萝卜素的生物合成途径是植物所特有的。近年来，有报道称叶绿素前体如原卟啉IX通过其光动力作用表现出植物毒性活性。本研究旨在从色素生物合成途径的中间体和生物合成调节剂中筛选出新的植物生长调节剂。研究结果总结如下：1。研究了叶绿素前体、中间体和叶绿素通路调节剂对几种植物生长的影响。在所测试的天然化合物中，叶绿素的所有terapyrole中间体的前体d-氨基乙酰丙酸（ALA）在外源施用于植物时具有最强的除草作用。浓度为10^<-4> ~ 10^<-3> M的ALA溶液会造成白化，导致许多植物死亡。乙酰丙酸、二氧庚酸和加巴库林在较高浓度下也表现出植物毒性，如褪绿。从ALA的作用模式研究中发现，叶绿素中间体大量积累。原卟啉IX是主要的卟啉积累。这是已知的光敏剂在光线下产生单线态氧。因此，积累这种中间体的化学物质可能成为有效的生长调节剂。为了刺激植物中ALA的合成，研究了植物中ALA合成的调控机制。结果表明，ALA的合成受光和反馈抑制的影响。建立了水培禾本科植物生长调节剂的生物测定系统

Chlorophylls and carotenoids biosynthetic pathways are peculiar to plants. Recently, it was reported that chlorophyll precursor such as protoporphyrin IX showed phytotoxic activity by its photodynamic action. This study aimed to screen new plant growth regulators available for herbicidal use from intermediates of the pigments biosynthetic pathways and modulators of the biosynthesis. The results of the study are summarized as follows.1.Effect of chlorophyll precursors, intermediates, and modulators of chlorophyll pathway on growth of several plant species were surveyed. Among the natural compounds tested, d-aminolevulinic acid (ALA), precursors of all the terapyrrole intermediates of the chlorophyll are most herbicidal when they were exogenously applied to the plants. ALA solution sprayd at 10^<-4> to 10^<-3> M caused bleaching and killed many plant species. Levulinate, dioxoheptanoic acid and gabaculine also showed phytotoxic activity such as chlorosis at higher concentrations.2.From the mode of action study of ALA,huge accumulation of chlorophyll intermediates was identified. Protoporphyrin IX was the prevalent porphyrin accumulating. This known to photosensitizer generating singlet oxygen under light. Therefore, chemicals that accumulate this intermediate may become effective growth regulator.3.To stimulate ALA synthesis in plants, regulation of ALA synthesis in plants was investigated. It was shown that ALA synthesis was regulated by light and feedback inhibition of the products of the pathway.4.Bioassay system of plant growth regulators using hydroponically grown barnyardgrass seedlings, most troublesome annual weed in rice paddy, was established