Twenty years of brassinosteroids: Steroidal plant hormones warrant better crops for the XXI century

The discovery of brassinosteroids (BS) just over 20 years ago opened a new era in studies of bio-regulation in living organisms. Previously, the only known role of steroids as hormones was in animals and fungi; now a steroida l hormone in plants had been added. Progress in brassinosteroid research ha s been very rapid. Only 20 years passed between the discovery of brassinoli de, the first member of the series, and the application of brassinosteroids in agriculture. Although the other plant hormones have been studied for a much longer period, there has not been similar development. Within the last couple of years two books on brassinosteroids (Khripach VA, Zhabinskii VN, de Groot A. 1999. Brassinosteroids-a new class of plant hormones. San Dieg o: Academic Press; Sakurai A, Yokota T, Clouse SD, eds. 1999. Brassinostero ids: steroidal plant hormones. Tokyo: Springer Verlag) have been published, but many new data have appeared since that time. Many of the more recent d ata is devoted to molecular biological aspects of BS and has helped to crea te a vision of their role in plants and their mechanisms of action. New dis coveries of the physiological properties of BS allow us to consider them as highly promising, environmentally-friendly, natural substances suitable fo r wide application in plant protection and yield promotion in agriculture. This aspect of BS is the main subject of this Botanical Briefing. (C) 2000 Annals of Botany Company.