鼓槌石斛未成熟种子无菌萌发与小苗组培快繁的研究

STUDY ON STERILE GERMINATION AND IN-VITRO RAPID PROPAGATION OF DENDROBIUM CHRYSOTOXUM LI NDL.

本文报道鼓槌石斛未成熟种子在离体培养下发育成苗及离体快繁的研究结果．在附加1．0mg／LBA和0．5mg／LNAA的MS培养基上，鼓槌石斛未成熟种子接种后最初一个星期内，发育较慢，以后明显较快，至接种后2w时，种胚的长度或直径增加到接种前的1．5倍～2．0倍；至接种后3w时也有10％～15％的种胚突破种皮，形成裸露的种胚（原球茎体）；至接种后第4w时，可以观察到裸露的种胚开始萌芽，首先出现盾片子叶，以后第1，第2和第3片幼叶逐渐依次形成．从接种到第1片幼叶（真叶）形成时，约需80d．在初代培养基上未观察到根的形成，这可能与初代培养基中追加有1．0mg/LBA有关．由于同一蒴果中的种子是发育不同步的，故种胚、原球茎体以及幼苗的发育也是不同步的．培养物（无根幼苗及原球茎体）转接到成分与初代培养基完全相同的新鲜培养基上进行继代培养时，原球茎体及无根幼苗的基部会增殖形成新生的原球茎体，继而发育成幼苗；少部分原球茎体在发育成苗之前脱分化形成颗粒状愈伤组织，这种愈伤组织可以增殖形成新的愈伤组织；或分化出芽点，继而发育成幼苗；或分化出原球茎体，继而再发育成幼苗．生根壮苗培养过程中试验了5种基本培养基，其适应性按顺序依次为H〉1／3MS〉1／2MS〉SJ-1〉MS．

This paper deals with the development of the seed embryo and plantlet formation of Dendrobium chrysotoxum Lindl. under the in - vitro culture of the un - matured seed and with the rapid propagation of Den. ehrysotoxum via tissue culture. On the MS medium supplemented with 1.0mg/L BA and 0.5 mg/L NAA, the development of the un - matured seeds was slow in the first week after inoculation. Latter the development of the seed embryo speeded up distinctly, which the length and the diameter of the seed embryo inoculated for two weeks were 1.5 times ; 2.0 times as that before inoculation. When cultured for 3 weeks, about 10 % to 15 % of the seed embryos broken out the seed coats to form the naked embryos. Up to the 4th week after inoculation, a few of naked seed embryos were observed to begin germination： at first the seed leaf appeared, then the first, the second and the third young leaves formed successively. It took 80 d or so from the inoculation to the formation of the first leaf. No root emergence was observed on the initial medium, which might due to the supplement of 1.0 mg/L BA to the medium. Because the development of the seed embryos is unsynchronous, the development of proteeorm- like bodies and the young seedlings are unsynchronous. When they were transferred onto the fresh medium （with the same complements as the initial medium） for subculture, then the newly- formed proteeorm - like bodies would develop into the plantlets. A few of proteeorm - like bodies were dedifferentiated to form the granular callus before they develop into seedlings. This kind of callus might be proliferated to form new callus, or differentiated to form bud spots and then develop into young seedlings, or dedifferentiated to form the proteeorm - like bodies developing into plantlets. 5 kinds of the basic media were tested for the rooting culture and promoting plantlets of Den. chrysotoxum Lindl. and the adaptability is in the sequence of H 〉 1/3MS 〉 1/2MS 〉 SJ- 1 〉MS.