Influence of 6-Benzylaminopurine on Fruit-Set and Seed Development in Two Soybean, Glycine max (L.) Merr. Genotypes

Abstract

The influence of 6-benzylamnopurine (BA) (5,6,18). The high levels of cytokinins in developing seeds and fruits (6,16,25) are indicative of a function of this type of hormone during periods of active cell division and high assimilate demand in the growing embryonic tissues.Among the legumes, pea, lupin and soybean fruits have been shown to contain cytokinins or cytokinin-like activity (6-9, 17).

Effects of Source/Sink Ratio and Cytokinin Application on Pod Set in Soybean

“…Several previous studies indicated that cytokinin plays a critical role in pod set (Crosby et al, 1981;Dyer et al, 1987;Peterson et al, 1990;Mosjidis et al, 1993;Kokubun and Honda, 2000;Nagel et al, 2001). Therefore, we examined whether pod number can be increased by applying cytokinin to the plants with a high source/sink ratio.…”

“…BA solution was prepared as described by Crosby et al (1981). Briefl y, a small quantity of BA was dissolved in 1 N KOH and diluted to 2 mM with 16 mM K-phosphate buffer (pH 6.4) containing 0.05% (v/v) Tween 80.…”

“…The BA solution was applied, using a syringe, as a drop to individual racemes (0.1 mL per raceme). The applications were made at 3 and 15 DAA (days after anthethis, when the fi rst fl ower in the plant opened) when the infl orescence was at developmental stages of R1 and R3 (Fehr et al, 1971), respectively, because these stages were found to be most responsive to BA application (Crosby et al, 1981;Peterson et al, 1990). Control plants received the solution without BA.…”

“…Endogenous cytokinins detected in exudate showed a maximum concentration during a period from 0 to 9 days after anthesis, when most fl owers are destined to either initiate or abort pods (Heindl et al, 1982;. The application of BA to racemes reduced abortion and increased pod number (Crosby et al, 1981;Carlson et al, 1987;Dyer et al, 1987;Peterson et al, 1990;Mosjidis et al, 1993;Reese et al, 1995;Nagel et al, 2001). Within individual racemes, pod set probability at different fl oral positions was closely associated with the cytokinin concentration (Kokubun and Honda, 2000).…”

Promoter tagging with a promoterless ipt gene leads to cytokinin‐induced phenotypic variability in transgenic tobacco plants: implications of gene dosage effects

“…We conclude that under our growth conditions the endogenous cytokinin concentrations of wild-type plants are optimal. We cannot exclude, however, that specific promoters exist that would direct ipt gene expression in such a way as to obtain a yield increase, as was observed when cytokinins were added to developing grains of wheat (Crosby et al, 1981;Trckovd et al, 1992).…”