Abstract
In vitro cultures were used to study the development of axillary bud and stolon tip explants of cultivated strawberry (Fragaria × ananassa Duch.). Explants cultured on Murashige-Skoog basal media containing kinetin at 1, 5, or 10 mg/liter developed into leafy shoots. Low concentration of kinetin (1 mg/liter) promoted the development of both types of explants into single shoots while higher concentration (10 mg/liter) promoted production of multiple leafy shoots developing from axillary buds of the earlier formed leafy shoots. NAA at 1 mg/liter promoted callus growth from both types of explants. Axillary bud explants developed into stolons when cultured on media containing gibberellic acid (GA3) at 5, 10 or 20 mg/liter. Stolon apices developed into leafy shoots while the second axillary stolon buds of the tips were inhibited when the explants were cultured on GA3-containing media. Combinations of GA3 and kinetin induced the development of axillary bud explants into structures intermediate in form between those of stolons and leafy shoots. Stolon apices and stolon axillary buds at the stolon tips developed into leafy shoots and continuing stolons, respectively, when the explants were cultured on a kinetin-containing medium for one week, and then transferred onto a GA3-containing medium. Thus, the developmental pathway of axillary strawberry buds was shown to be responsive to a balance between GA and cytokinins following removal from apical dominance.
m above sea level) and were used as plant materials. The axillary buds of terminal shoot buds of rhizomes were used as the explant sources ( Fig. 1A ). Shoot buds were first washed with detergent and rinsed under running tap water for 1 min and then
Abstract
Cytokinins applied to axillary buds of apple shoots overcame apical dominance. Axillary buds on actively growing apple shoots produced spurs and lateral branches when treated with cytokinins. Buds on shoots that had not received sufficient chilling to break rest were also induced to grow with cytokinins.
Abstract
Sprays of a synthetic cytokinin, 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA), applied to seedlings of Macadamia tetraphylla L. in the greenhouse resulted in sprouting of axillary buds, and reduced growth of the terminal shoot. Terminal removal caused lateral shoot development in more seedlings than PBA.
Abstract
Application of 6-(benzylamino)-9-(2-tetrahydropyranyl-9H-purine (PBA); 6-benzylamino purine (BA); and ethyl 5-(4-chlorophenyl)-2H-tetrazole-2-acetate (PP528) to seedlings of Macadamia tetraphylla L. in the greenhouse resulted in sprouting of axillary buds. PBA and BA were more effective than PP528. No axillary buds sprouted on untreated seedlings.
Nonbranching chrysanthemums [Dendranthema × grandiflorum (Ramat.) Kitamura] are preferred because they require less labor in disbudding. High temperature is responsible for this phenotype of not having axillary buds or poor lateral shoot development. This study attempted to find out the effect of temperature and identify the involvement of endogenous polyamine contents in axillary bud formation of nonbranching chrysanthemum cv. Iwanohakusen. Plants were treated at 22, 26, 30, 34, and 38 °C for 9 hours midday for 2 months. Polyamine content [putrescine (Put), spermidine (Spd), spermine (Spm)] was analyzed 1 month after treatment and axillary buds were counted when the flowers opened. Results revealed that viable axillary buds decreased remarkably at 30 and 34°C. It was also found out that not only low temperature, but also the excessively high temperature of 38 °C induced axillary bud formation. Exposure to 38 °C increased the Put contents and resulted in high Put/(Spd + Spm) ratio as 22 °C, 26 °C. Temperature of 30, 34 °C lowered Put/(Spd + Spm) ratio. Results further showed that not polyamine contents, but polyamine ratio (Put/Spd + Spm) or transformation of Put to Spd and Spm may be involved in the axillary bud formation in nonbranching chrysanthemum.
Actively growing shoots of peach [Prunus persica (L.) Batsch] were collected every 2 weeks throughout the 1989 growing season. The samples were sectioned longitudinally and transversely to observe axillary bud initiation, which occurred in all samples collected. Differentiation of axillary bud meristems from early season samples (mostly normal nodes) included apical and prophyll formation, with procambium connected to the stem procambium. Little to no differentiation of such structures occurred in the late-season samples (mostly blind nodes). Other results suggest that blind node formation is a consequence of a lack of bud differentiation rather than a failure of bud initiation.
Abstract
Spray applications of NAA or NAA ethylester at 1000 ppm acid equivalent (A.E.) reduced axillary bud number by 30% and 21%, and weight by 73% and 52%, respectively, on pinched potted chrysanthemums, Chrysanthemum ×morifolium Ramat. ‘Mountain Snow’ and ‘Mountain Peak’. Diameter of floral sprays and vegetative heights also were reduced with increasing concentrations. Flower number was not affected by the treatments. NAA treatments caused leaf epinasty, but NAA ethylester treatments did not. Chemical names used: 1-naphthaleneacetic acid (NAA).
Abstract
A micropropagation procedure was developed to regenerate plants via tissue culture from excised axillary buds of harvested and stored heads of field-grown crisphead (iceberg) lettuce (Lactuca sativa L.). The procedure permits rescue of lettuce germplasm that shows resistance to postharvest physiological disorders and diseases. This procedure was used successfully to regenerate plants of ‘Winterhaven’ lettuce, which showed resistance to russet spot. More than 50% of the excised buds gave rise to viable plants.
Watermelon (Citrullus vulgaris Schrad.) is a widely grown crop throughout the tropics and subtropics. In Mexico, it is an economically important crop. In vitro adventitious shoot regeneration of watermelon has been reported from shoot tip culture, leaf, hypocotyl, and cotyledons. Hence, the objective of this study was to evaluate in vitro plant regeneration from axillary buds of triploid watermelon. Axillary buds explants were prepared from shoot of commercial cultivar in field of 60 old day plants. Explants of 2 to 3 mm were incubated 2 weeks on Murashige and Skoog (MS) shoot regeneration medium containing 2.5 mg/L kinetin (KT) or indole-3-butyric acid (IBA), or gibberellic acid (GA3), followed by 3 weeks on shoot elongation medium supplemented with different combinations of the same phytohormones. The percentage of explants (83% to 90%) that produced shoots, expansion in size of explant (0.81–1 cm) and shoot length (6 mm) were highest in MS medium containing KT or IBA. In the shoot elongation step, shoot length (0.9–1 cm) and leaves number (6–7) were highest in MS medium supplemented with 2.5 mg/L of KT or GA3 and 0.2 mg/L IBA, but the better induction of roots in elongated shoot occurred on MS medium with 2.5 mg/L KT and 0.2 mg/L IBA. The results show that axillary buds from watermelon is an alternative for the micropropagation of this crop.