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Abstract
This investigation was carried out during the period from 2004 to 2007 in Plant Biotechnology Research Lab, Fac. Agric., Cairo Univ., Giza, Egypt.
This study included two parts, the first part aimed to study some factors affecting prototoplas, namely isolation, culture, and regerneration, as well as obtaining putative tetraploid hybrids through chemicaland electrofusion techniques. The study revealed that one step isolation method was successful with 6 genotypes namely 67, 803 and 808 (dihaploid clones), S. bulbocsatanum, (diploid wild) and Forelle and Diamand (tetraploid cvs). On the other hand, the two steps isolation method was the most sutable one for isolation of the wild species S. pinnatisectum. Shooting potential varied in different genotypes. A putative tetrapolid somatic hyprid was obtained through chemical fusion between clone 803 and S. bulbocastanum. Also two tetraploid somatic hybrids were obtained by the electrofusion between the dihaploid clone 808 S. pinnatisectum. The morphologica characters and RAPD analysis confirmed such fusions.
The second part of this study aimed to investigate the effect of some factors, namely concentrations of benzyl burine (BA), jasmonic acid (JA) sucrose and active charcoal on microtuber formation of six potato genotypes, four tetraploid, viz. Diamant, Picasso, Santa and Forelle and two dihapliod, namely 805 and 808. Potato genotypes responded differently to such factors, where Forelle cv. showed the best performance regarding microtuber number per jar, average weight of microtuber, and microtuber yield per jar. Increasing sucrose concentration up to 12% and adding active charcoal at concentration of 5 g/l in medium having 10 mg/l BA caused a remarkable increase in microtuberization parameters in all cultivars. On the other hand, increasing sucrose concentration or adding 5 g/l active charcoal to MS medium having 5 mg BA /l promoted microtuber formation in some cultivars, and inhibited this process in others. There was interaction between concentration of JA,sucrose and AC on the microtuberization of the different potato genotypes. Generally, the highest microtuber yield per jar was recorded in cv. Diamant in MS medium having 2.5 µM JA, 80 g/l sucrose and 5 g/l AC.