在無人為篩選壓力下由原生質體融合得到兩種菸草的體細胞雜種

Differential recovery of somatic hybrids from protoplast fusion of two Nicotiana species in the absence of artificial selection

分別分離兩種青春草Nicotiana plumbaginifolia與N. sylvestris葉肉原生質體，等量混合後利用PEG誘導融合，並培養於對二親本無篩選壓力之培養基中，在所得到的再生植株中， 體細胞雜種約佔78%，而各種染色體組組合之體細胞雜種，在雜種植株中所估的比率分別為PPSS 84.8%，PPPPSS 8.7%，PPPPSSSS 6.5%。任一染色體組組合之雜種植株皆可觀察到染色體數目或構造上的變異，顯示此二種菸草染色體間存在相當程度的不相容性。再生植株經染色體鑑定、外型比較，及同功酵電泳圖譜分析的結果，發現早期分化所得到的植株全為體細胞雜種，此現象當可視之為雜種優勢。

Mesophyll protoplasts of Nicotiana plumbaginifolia (PP) and N. sylvestris (SS) were mixed at equal density, treated with polyethylene glycol (PEG) and then cultured in medium with no selection pressure against parental cells. Cytological, morphological, and biochemical studies showed that about 78% of plants regenerated from protoplast fusion were somatic hybrids. The ploidy levels of somatic hybrids varied, and the frequencies of plants with PPSS, PPPPSS, and PPPPSSSS genome constitutions were 84.8%, 8.7%, and 6.5%, respectively. Aneuploid numbers and chromosome structural changes were common in somatic hybrids. The successful recovery of somatic hybrids in the absence of artificial selection is attributed to a high viability of the fusion products following PEG treatment and a fast rate of growth and development of hybrid cells during in vitro culture.