蝴蝶蘭種原根尖染色體染色技術之探討

Study on Root Tip Squash and Staining Techniques of Phalaenopsis Orchids

本研究之目的為探討及修正蘭心的根尖染色體染色技術，以期能清晰觀察計算根尖染色體數，以利於蝴蝶蘭的育種計畫。在特定時間採取根尖，以細胞分裂抑制劑處理2小時，並以Carnoy’s solution固定一夜。經軟化後，加入aceto-orcein染色，壓片後於光學顯微鏡下鏡檢。結果顯示，在正午前後採取根尖，並以0.1% colchicine：0.002M 8-HQ＝2：1的預處理液進行前處理，可清楚地觀察到大部分雜交種植株根尖的染色體。供試品種的染色體數從原種的二倍體2n＝38到雜交種的五倍體2n＝95，多數調查的雜交種為四倍體（2n＝76）。而諸多染色過程的條件如軟化時間仍必須依材料的不同而加以調整。 The purpose of this study is to modify and develop root squash technique suitable for observing and counting somatic chromosome numbers of Phalaenopsis species and hybrids in breeding programs. Under certain time of a day, roots were harvested and treated with mitotic inhibitors for 2 hours. After fixation in Carnoy’s solution overnight, maceration, and staining with aceto-orcein, the root tips could be squashed and observed under light microscope. It was shown that root tips were best harvested around noon time and pretreated with 0.1% colchicine : 0.002M 8-hydroxyquinoline = 2 : 1. Root tip chromosomes of most hybrids were visible when adopting the procedure. The chromosome numbers of some diploid species is 38. The ploidy level of phalaenopsis hybrids ranges from diploid (2n = 38) to triploid (2n = 57), tetraploid (2n = 76) and more than pentaploid (2n >95). Most examined hybrids with standard flowers belong to tetraploid. To optimize chromosome counting for most phalaenopsis hybrids, maceration time and other pretreatment procedures need to be considered to obtain better resolution.