酪梨組織培養之研究

Abstract

本研究主要探討酪梨莖頂離體培養之方法，培殖體取自兩種抗病砧木品種''G755''及''Toro Canyon''，以及''Lula''幼年實生苗。實生苗''Lula''品種之初代培養以1/2MS添加BA 1~2 mg/l處理芽體之成活率皆可達100%，幼梢長度達10.5mm。繼代培養時，以雙相培養基(上層液態為1/2MS加BA 4 mg/l；下層為1/2MS固態)較有利於芽體增生，平均芽數4.8/培殖體，平均幼梢長度為8.3mm。誘導''Lula''發根可先以IBA 10mg/l暗處理7天，再移至不含auxin之環境下培養3週有17%發根，平均根長10.2mm。 砧木品種之初代培養以不同鹽類濃度(1/4MS、1/2MS、MS及2MS)與蔗糖濃度(1、2、3、4及5%)試驗，結果顯示''G755''成活率較''Toro Canyon''高，且褐化程度較低。''G755''以1/2MS為基本鹽類，3%蔗糖之液態紙橋培養，培養基中添加kinetin 2mg/l，培殖體大小取5mm較2mm有利於幼梢生長，且基部不會形成大量之癒傷組織。但初代培養添加BA 2mg/l時，基部會形成大量的癒傷組織，而導致培殖體之成活率降至5%。另外，1/2MS基本培養基中添加0.1%活性碳亦可有效抑制初代培養褐化之發生。增殖培養時，添加TDZ(0.1~0.5mg/l)可刺激芽體之增生，芽體之壞疽率較其他濃度之壞疽率低。

Summary The objective of this study was to develop an effective method for in vitro propagation of avocado (Persea americana Mill.). A 100% survival was obtained when ''Lula'' was cultured in a 1/2MS medium supplemented with 2mg/l BA. In subculture, the multiplication rate of shoot in the double phase medium was higher than in the solid and paper bridge media. The average shoot number was 4.8 per explant and average shoot length was 8.3 mm. In ''Lula'', the rooting procedure had 7 days in dark in a medium containing indole-3-butyric acid (IBA) 10mg/l and four weeks in an auxin-free medium. Shoot tips harvested from two rootstock selections ''G755'' and ''Toro Canyon'' mature trees, and one commercial cultivar ''Lula'' young seedling were used in this study. Medium contained different salt levels (1/4MS, 1/2MS, MS & 2MS) and sucrose concentrations (1%~5%) were tested. The results showed that the survival percentage of ''G755'' was higher than that of ''Toro Canyon'' and ''G755'' had lower percentage of browning. Shoot growths were enhanced when 5mm explants were used, compared with 2mm explants, and less callus was formed. A lot of callus formed at the bases of explants cultured in the medium contained 2mg/l BA callus and the survival percentage of these explants decreased to 5%. The browning rate was decreased by adding 0.1% active charcoal to the 1/2MS basic medium. The multiplication and elongation rates of ''G755'' were significantly increased by supplying 0.5mg/l TDZ to the subculture medium, and the rate of shoot necrosis was reduced by the treatment.