ISHS Acta Horticulturae 394: Plant Bioregulators in Horticulture
EVOLUTION OF A NOVEL UREA-TYPE CYTOKININ :HORTICULTURAL USES OF FORCHLORFENURON |
| Authors: | Y. Arima, K. Oshima, K. Shudo |
| Keywords: | Forchlorfenuron, N-(2-chloro-4-pyridyl)-N'-phenylurea, Urea-type cytokinins, Structure-activity relationships, Cytokinin specific binding protein, Fruit enlargement, Fruit setting |
| Abstract:
We have found that the synthetic urea-type cytokinin N-(2-chloro-4-pyridyl) -N'-phenylurea (forchlorfenuron) has a much higher cytokinin activity than any of the adenine-type cytokinins. The biological response of competitive antagonists suggests forchlorfenuron and benzyladenine (BA) have a common active site. Using forchlorfenuron as a probe, cytokinin specific binding protein (CSBP) was isolated from etiolated mung bean seedlings. Many cytokinins showed competitive binding to this (CSBP) and their affinities for it corresponded well with their cytokinin activity. This CSBP is a more plausible cytokinin receptor than any other binding protein reported. In horticultural uses, forchlorfenuron promotes the fruit size of kiwifruits, grapes, pears and apples. In grower trials for evaluating the effects of forchlorfenuron on kiwifruit production in New Zealand, the average fruit weight with forchlorfenuron treatment was 27 to 46 % heavier than those of untreated fruit. The rejection rate of fruit was not affected by forchlorfenuron. Forchlorfenuron apparently promotes the fruit setting of melons, watermelons, pumpkins and grapes in commercial production. Application together with GA, used as the first treatment, extends the period of GA treatment for grapes. | |
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