[Analysis of tobacco regeneration plants from the protoplasts produced by electrofusion [corrected] in space]

Vacuolated mesophyll protoplasts of Nicotiana rustica L. were electrically fused with evacuolated protoplasts of the same genus (N. tabacum cv. 'Gexin No.1') during a 7-day space flight in the Chinese spacecraft "SZ-4". The initial cell division leading to micro-callus formation took place after landing (Fig.1). Higher plating efficiencies were observed in the flight samples than the control culture, but the frequency of plantlets regeneration reduced by about 20% of the control (Table 1). The hybrid characters were tested by chromosome counting, isozyme analysis and comparison of morphological characteristics (Figs.2-4). About 32% of the regenerates showed hybrid character. Leaf morphological modifications were found in 3 hybrids, i.e., H23, H25 and H27. After backcrossing with N. rustica, alterations in flower color and leaf shape occurred in the somatic hybrid H23 (Fig.5). These results demonstrate that the hybrids formed under microgravity condition could regenerate fertile plants.