Plant growth regulating action of brassinolide. I. The effect of brassinolide on the ripening of rice plants under the low temperature condition.

Distribution of Assimilates to Each Organ in Rice Plants Exposed to a Low Temperature at the Ripening Stage, and the Effect of Brassinolide on the Distribution

“…Neither did BR largely influence the contents of glucose and fructose. However, BR treatment strikingly increased the 1 ,000-grain weight and the percentage of ripened grains in the rice plant in both of the greenhouse and phytotron.Key words :Assimilate, Brassinolide, Promotion of Ripening, Rice ( Oryza sativa L.), Ripening Stage, Starch, Sucrose.The plant hormone brassinolide (BR) promotes the ripening of rice plants (Hirai et al, 1991) as well as isoprothiolane (Ohtsuka and Saka ,1989) and hydroxyisoxazole (Ota, 1981). In a previous study (Fujii and Saka, 1992), we found that BR applied at around heading time promoted ripening of rice plants through the promotion of the translocation of assimilates to panicles at the ripening stage.…”

“…On the other hand, BR promotes the ripening in rice grains, whereas it prevents or reverses the damage caused by environmental stress, especially under low temperature conditions (Hirai et al, 1991;He et al, 1991). Therefore, it is important to examine the effect of BR on the distribution of assimilates to each organ after the flowering time, and to elucidate how BR modifies the effect of environmental stress on the assimilate distribu- In this study, rice plants after flowering were grown in the phytotron kept of a low-temperature under natural daylight, and the accumulation and distribution of assimilates to each organ at the late milk-ripe and late dough-ripe stages were examined to determine the effect of a low temperature on the dynamics of carbohydrate.…”

“…The plant hormone brassinolide (BR) promotes the ripening of rice plants (Hirai et al, 1991) as well as isoprothiolane (Ohtsuka and Saka ,1989) and hydroxyisoxazole (Ota, 1981). In a previous study (Fujii and Saka, 1992), we found that BR applied at around heading time promoted ripening of rice plants through the promotion of the translocation of assimilates to panicles at the ripening stage.…”

“…On the other hand, BR promotes the ripening in rice grains, whereas it prevents or reverses the damage caused by environmental stress, especially under low temperature conditions (Hirai et al, 1991;He et al, 1991). Therefore, it is important to examine the effect of BR on the distribution of assimilates to each organ after the flowering time, and to elucidate how BR modifies the effect of environmental stress on the assimilate distribu-tion.…”

Brassinosteroids and Monoglycerides with Brassinosteroid-like Activity in Immature Seeds ofOryza sativaandPerilla frutescensand in Cultured Cells ofNicotiana tabacum

“…3 -5) The application of BRs to rice (Oryza sativa) has been investigated by several workers, revealing that it enhanced the cold tolerance and crop yield of rice. 6,7) However, endogenous BRs in rice have only been investigated for the shoot of an Italian cultivar, Arborio J-l (Indica type).8) Therefore, we investigated endogenous BRs in immature seeds of a Korean cultivar, Tongjinbyeo (Japonica type). Another aim in this study was to examine whether mono glycerides can be generally detected as biologically-active compounds in plant extracts, because monoolein and monopalmitin have recently been identified in Cassia tora seeds as active principles with bras sino steroid-like activity.9) For this purpose, we also analyzed immature seeds of Perilla !rutescens, whose leaf and seed oil are used for food and medicine, as well as cultured cells of tobacco (Nicotiana tabacum).…”