Studies on plant growth substances in Japan before 1945

• Published in: Plant Biotechnology 2007, Vol.24(2), pp.155-163
• Main Author: Katsumi, Masayuki
• Format: Article
• Language: English
• Subjects: Early auxin studies; inhibitor of self-incompatibility; plant hormone studies in Japan; pollen hormone
• ISSN: 1342-4580; 1347-6114
• DOI: 10.5511/plantbiotechnology.24.155

The idea that a specific chemical stimulus is involved in some processes of plant development was introduced by European plant scientists in the early 20th century. After the discovery of auxin by Went in 1926, this hormone became a subject of intensive studies in the physiology of plant growth and development. In Japan, studies on auxin started in the middle of the 1930s. At that time, gibberellin was discovered in Japan. Unfortunately, gibberellin was regarded as a fungal toxin and no special attention was paid to its physiological significance. The first paper on auxin in Japan was published by Masayuki Nagao in 1936, dealing with its transport in the root, which was then a subject of dispute. Before World War II (~1940) there were only about ten auxin researchers, excluding those in applied areas. In this article I will introduce their studies and some of the applied studies. I will also pay special attention to a series of work by Sadao Yasuda who was a pioneer researcher of plant reproductive physiology in Japan. He studied self-incompatibility (1927–1932) and parthenocarpy (1930–1940) which are related to plant growth substances. He demonstrated that a special substance (inhibitor) was involved in self-incompatibility. This is probably the first case in Japan for demonstrating the involvement of a regulatory inhibitor in plant development. In his study on parthenocarpy he concluded that “pollen hormone” and auxin are identical in their physiological nature.