γ射線照射及葉片培養對彩葉芋變異之影響

Effects of γ-rays Irradiation and Leaf Blade Culture on Mutations in Caladiums

放射線照射與組織培養技術結合的突然變異誘導方法、可提高變異個體的出現機率並有效的獲得變異個體，該種方法近年在園藝作物的育種上得到了快速進展。本研究首先調查r射線的塊莖照射對彩葉芋塊莖出芽及植株變異之影響，同時探討r射線照射及葉片培養結合的誘導變異方法對彩葉芋變異之影響。28個品種的塊莖以r射線15Gy照射後、其塊莖的萌芽比對照組明顯延後，而且最初展開的數枚葉片出現了不規則的葉形、但是後續生長的葉片又恢復正常。'Frieda Hemple'經r射線照射之塊莖所長出的葉片中，出現了葉色由紅色變成白色的改變，該種改變只是發生在中途展開的一至二枚葉片上，後續長出的葉片又恢復正常葉色。另外，'Frieda Hemple'經r射線照射之塊莖所長出的葉片作為培植體，由葉片培養的再生個體中同樣出現了白色葉色的改變，然而改變發生在整體植株上，且變異率因培植體類型而不同。其中、一半為白色葉色變異葉片由來之再生個體的變異率為34.2%;而展開之第一、二、三、四枚葉片由來的再生個體變異率依次為54.5%、19.4%·4.3%、1.7%;未經r射線照射之塊莖所長出的葉片作為培植體時再生個體中未觀察到白色葉色變異。

Mutant breeding method combining radiation irradiation and tissue culture technique is a efficient technology. This technique can induce variation much more quickly and multiply than traditional radiation breeding technique on many plant models. There has been no report of applying this new technology on the induction of variations in caladium plants. We therefore conducted a study to examine the efficiency of this new technique. Twenty-eight varieties of tubers from caladium were used for this study. Thirty tubers were used in each variety. Fifteen gray of r -ray irrad國tion were delivered to each tuber before planted. Only one variety'Frieda Hemple'was used for farther processed by tissue culture with the half leaf changed into white color or the first to forth leaves grew from irradiated tubers. As expected, the time of emergence of the irradiated tubers was later than those of not irradiated tubers. An irregular shapes and disorder blotches of the leaves were appeared in some earliest expending leave, but in the subsequent expending leaves returned to normal shapes and colors in groups of r ray irradiation. However, the white leaf color mutation on one or two leaves of·Frieda Hemple'got from r ray irradiated tubers. and in the subsequent expending leaves returned to normal.. But the mutant of'Frieda Hemple'got from leaf blade culture can last forever because we have further cultured that mutants for the next generation without seeing difference. The mutation rate in white leaf color of'Frieda Hemple'was 34.2% from the leaf color mutant and was 54.5% from the first expending leaf, which were I 9.4%, 4.3%, I. 7% and 1.3% from that of second to fifth expending leaves respectively. In conclusion, we have proved that this new technique combining r ray irradiation and leaf blade culture can be successfully increasing the rate of mutation in caladium.