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Ray F. Dawson

Diosgenin is a steroidal aglycone occurring in certain species of Dioscorea native principally to eastern Mexico. In the 1940s, diosgenin became a much-sought-after intermediate for the chemical synthesis of certain corticosteroids and structurally related fertility regulants. Various difficulties of access to native sources led to attempts at plantation production. One of these, supported by the Upjohn Company between 1962 and 1980, was located on the Pacific coast of Guatemala and is described herein from the standpoint of technology development. The Dioscorea plant produces a long, coarse vine that requires support. The deep-growing, fleshy rhizome contains the diosgenin and, at harvest, must be removed from soil depths up to 1 m. Dry rhizome yield depends on supply of readily available (low-tension) soil water. Sites located over abundant water reserves give satisfactory rhizome yields, but diosgenin concentrations fall to uneconomically low levels under such circumstances. By 1980, diosgenin had been displaced by two products of soya oil processing, stigmasterol and sitosterol, which became available as a result of advances in microbial fermentation technology. Consequently, the cultivation of Dioscorea was abandoned.

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Jiaqi Hu, Hye-Ji Kim, Houbin Chen, and Biyan Zhou

, abscisic acid was shown to promote flowering, whereas GAs inhibit flowering ( Chen et al., 2014 ; Cui et al., 2013 ). Brassinosteroids are a group of polyhydroxylated plant steroid hormones that are ubiquitously present throughout the plant kingdom and

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Min-Jung Lee

et al., 2005 ). Cortisol is a steroid hormone produced by the adrenal gland ( van Cauter, 1987 ), which is released in response to stress. Its primary functions are to increase blood sugar and influence immune system activity when the body is

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Clíssia Barboza da Silva, Julio Marcos-Filho, Pablo Jourdan, and Mark A. Bennett

). 24-Epibrassinolide, which belongs to the group of steroid hormones called BRs, is among the growth regulators included in priming treatment. This bioregulator occurs naturally in plant cells at very low concentrations ( Mandava, 1988 ); therefore

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Shanshan Sun, Mengying An, Liebao Han, and Shuxia Yin

overproduced ROS when plants were subjected to stress. Brassinosteroids (BRs) are a new group of steroid hormones of plants, which is widespread in plant pollen, seeds, stems, leaves, and other organs. BRs exhibit high physiological activity even at low

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Ju Ding, Kai Shi, Yan-Hong Zhou, and Jing-Quan Yu

phytohormones that are structurally similar to animal and insect steroid hormones. They control a broad range of processes, including seed germination, stem elongation, cell division and expansion, xylem differentiation, plant growth, and apical dominance