Effects of Constituents of Media on the Growth of Broussonetia Callus Tissue

[摘要] Nutritional requirements were studied to establish a defined medium for callus culture of paper mulberry tree (Broussonetia kazinoki Sieb.), one of the Moraceae group. In May 1971, callus was induced from the stem segments of a Broussonetia seedlng (20 cm long) on Murashige and Skoog's basal medium (MS) containing 1 mg/l 2, 4-D. In August when the callus grew to a sufficient mass of cells for subculturing, transplanting was made to MS+2, 4-D and MS+Benzyl adenine (BA). Callus grew more rapidly in the medium containing BA, so during the next 2-6 passages BA medium was adopted for subculturing. In January 1972 the callus of the sixth passage was transferred to MS basal medium not containing any growth substances, since it was known that the Broussonetia callus could be cultured on auxin-free medium. Subcultures were thereafter made on MS basal medium in 25-30 day's interval. Materials used in this experiment were obtained from stock callus that had been maintained on auxin-free medium onto December l973. Of the three basal media, MS, Walter and Skoog and White nutrient medium the first one was the most suitable for Broussonetia callus culture. Myo-inositol was found to be an essential micro-element and the optimum concentration was 100mg/l. Vitamins should be half required because even if all the three vitamins, thiamin, pyridoxin and nicotinic acid were eliminated, the callus grew to some extent, although not so much as when all of them were added. It was noticeable that the Broussonetia callus showed an autotrophic feature against auxin requirement. The addition of NAA or 2, 4-D to the basal medium gave negative effect, whereas TIBA, one of the antiauxins, increased the growth rate of callus at a low concentration (10-6 M), although it severely depressed callus growth at a high concentration such as 10-5 M or 10-4 M, especially in the latter. Broussonetia callus seemed to become a habituated state against auxin requirement within a short period after inducing callus, because the callus tissue induced in ah another experiment showed the same autotrophic feature in the second passage as of the callus used in this experiment. The necrotic callus caused by high concentration of TIBA (10-4 M) recovered growth potency if transferred to basal medium or basal medium+BA, the latter being more effective. Abscisic acid depressed callus growth at a lower concentration than TIBA.

[学科分类] 农业科学（综合）