植物生长素是一种植物荷尔蒙，能够促进植物根系和果实生长，控制植物发育的所有阶段。例如，在黑暗的地方大豆可以发芽，经过光照，便可长出叶片进行光合作用；倒伏的植物最快情况下经过30分钟便可直立，这些植物对环境的应答反应都有生长素的参与。
日本理化学研究所公布，他们和农业食品产业技术研究机构以及东京大学组成的联合研究小组于世界上首次发现了阻碍植物“生长素”生物合成的抑制剂的存在。
鉴于生长素在植物成长控制中具有重要作用，其在农业栽培领域具有广泛的应用前景，但与其他植物荷尔蒙相比，人们对它的不了解尚不充分。生长素在植物体内含量甚微，其生物合成路径复杂，化学性质不稳定，设计生物合成抑制剂也极其困难。诸多问题导致了生长素的基础研究和相关应用滞后，目前仅限于在农业除草剂和植物调节剂中应用具有生长素活性的生长素亲体，但尚无控制生长素作用的有效药剂和技术。
该联合研究小组对模型植物拟南芥的遗传发现类型进行了大规模的破解，并对获得的数据进行分析，以寻找可控制植物荷尔蒙作用药剂，结果发现了妨碍生长素生物合成的候补化合物AVG和AOPP。研究小组通过对这些化合物的功能进行深入研究后，确认了阻碍生长素生物合成的物质。该研究成果将发表在4月出版的《植物和细胞生理学》杂志。
研究人员表示，利用植物生长素生物合成抑制剂，可培育出以前无法实现的生长素缺乏状态的植物，这将为研究生长素的机能及其复杂的生物合成路径提供思路。目前植物生长素的研究尚限定于模型植物，未来可将研究范围扩展至农作物等高实用性作物，有朝一日开发出控制植物生长的新药和技术，开拓出崭新的农业栽培技术，将对促进农业生产起到关键作用。
生物谷推荐原文出处：
Plant and Cell Physiology doi:10.1093/pcp/pcq032
Auxin-biosynthesis inhibitors, identified by genomics-based approach, provide insights into auxin biosynthesis.
Kazuo Soeno1,4,, Hideki Goda1,, Takahiro Ishii1, Takehiko Ogura1, Tomoe Tachikawa1, Eriko Sasaki1,2, Shigeo Yoshida1, Shozo Fujioka3, Tadao Asami2 and Yukihisa Shimada1,2,*
1 RIKEN Plant Science Center, Suehirocho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
2 Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan
3 RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan
4 National Agricultural Research Center for Western Region (WeNARC), National Agriculture and Food Research Organization (NARO), Senyu, Zentsuji, Kagawa 765-8508, Japan
Despite its importance in plant growth and development, the auxin biosynthetic pathway has remained elusive. In this study, we analyzed hormone series transcriptome data from AtGenExpress in Arabidopsis and found that aminoethoxyvinylglycine (AVG) had the strongest anti-auxin activity. We also identified other effective compounds such as L-aminooxyphenylpropionic acid (AOPP) through additional screening. These inhibitors shared characteristics in that they inhibited pyridoxal enzymes and/or aminotransferases. They reduced endogenous indole-3-acetic acid (IAA) levels in both monocots and dicots. L-AOPP inhibited root development of Arabidopsis in main root elongation, gravitropism, root skewing, and root hair formation. This inhibition was generally recovered after exogenous IAA treatment, and the recovery was almost completely to the level of non-inhibited seedlings. The compounds inhibited conversion from Trp to indole-3-pyruvic acid in enzyme extracts from Arabidopsis and wheat. Our data collectively suggest that the inhibitors directly blocked auxin biosynthesis, and that the major target site was Trp aminotransferase. This enzyme likely makes up one of the major biosynthesis pathways conserved among higher plants. Each inhibitor, however, demonstrated a different action spectrum in shoot and root of rice and tomato, indicating diversity in biosynthesis pathways between organs and species. Our results provide novel insights into auxin biosynthesis and action, and uncover structural characteristics of auxin biosynthesis inhibitors.
