澳洲坚果不同外植体愈伤组织诱导与不定芽增殖研究

以澳洲坚果品种'H2'的幼嫩茎段和种子为材料,获取腋芽、子叶和上胚轴等外植体,开展愈伤组织诱导及不定芽增殖研究,再通过石蜡切片法对不同愈伤组织的细胞结构进行观察,分析比较不同外植体诱导的愈伤组织性质与不定芽分化效果.结果表明:适合腋芽愈伤诱导和分化的培养基为MS+2.0 mg/L 6-BA+0.5 mg/L KT,腋芽...

Callus Induction and Adventitious Bud Proliferation in Different Explants of Macadamia integrifolia

The axillary buds, cotyledons and epicotyls which were obtained from young stem segments and seeds of Macadamia integrifolia ‘H2’ were used as the explants, the callus induction and adventitious bud proliferation, and then cytological observations of the different callus by paraffin slice were conducted to analyze and compare the callus properties and adventitious bud differentiation effects induced by different explants. The suitable medium for axillary buds was MS+2.0 mg/L 6-BA+0.5 mg/L KT, which had the large numbers of callus and the adventitious bud regeneration coefficient was 3.49. The suitable medium for cotyledon callus induction was MS+2.0 mg/L TDZ+ 200 mg/L CH, the callus in this medium were green and tight, the induction rate was 82.2%, the browning rate was 8.9%, the cooperation of CH and TDZ not only helpt to improve the induction rate of cotyledon callus, but also reduced the browning rate. The optimal medium for adventitious buds of cotyledon callus differentiation was MS+1.0 mg/L KT+0.2 mg/L NAA+1.0 mg/L GA₃, the adventitious buds grew well and the regeneration coefficient was 5.40. The suitable medium for epicotyls adventitious bud differentiation was MS+1.0 mg/L KT+0.5 mg/L NAA, and the regeneration coefficient was 7.37. The adventitious bud differentiation ability of the three explants from high to low was epicotyl>cotyledon>axillary bud, and KT combined with other suitable concentrations of growth regulators could produce better adventitious bud differentiation effect, which is the key to promote adventitious bud differentiation. The cotyledons and axillary buds dedifferentiated into callus, and then redifferentiated into adventitious buds, but the epicotyls could directly differentiate adventitious buds without producing callus. The callus induced by axillary bud and cotyledon showed obvious differences in appearance and cytology. A relevant cytological observation showed that the axillary bud callus had large cell volume, high degree of vacuolation, little cytoplasm, and small nucleus, with scattered and irregular intercellular distribution, showing the characteristics of non-embryonic callus, while the cotyledon callus had compact cell arrangement, large nucleus, and deeply stained thick cytoplasm, showing the characteristics of meristematic cell. In comparison, cotyledon is an good material for callus induction, and epicotyl is the best explants for adventitious bud proliferation, the cotyledon callus have some characteristics of embryogenic callus and high differentiation capability, it can be used as a test material for genetic transformation and polyploid induction of macadamia.