| Using the synchronized tuberization system of single-node stem cuttings of in vitro potato plantlets, we have attempt to probe the signal function of sucrose in the induction of tuberization of potato plantlets. The main results were summarized as follows:1. The effects of different soluble sugars on in vitro tuberization of single-node stems of potato plantletswe have simulated the induction of exogenous sucrose with different sugars and sugar analogs at same concentration or same osmotic potential, the results shown that sucrose was an efficient factor for tuberization induction comparing with the other soluble sugars, its roles in the induction of tuberization were not related to the changes of osmotic potential and/or pH value of culture medium produced by sucrose itself, and not dependent on its known biological functions, e.g. supplied carbohydrates and energy for the growth and development of plantlets.2. The effects of Sucrose/Glucose absorption inhibitors on Sucrose/Glucose inducing potato tuberization and gene expressionUsing sucrose/glucose absorption inhibitors (pCMBS, NEM, Phloridzin) to disturb the absorption of sucrose/glucose, we found that exogenous sucrose was transported into the cells mainly as intact molecule by sucrose transporters, albeit part of them was catabolized into hexoses by cell wall invertase, and then transported into the cell with hexose transporters, Both of the transporting pathways are necessary for sucrose inducing tuberization of potato plantlets efficiently, but the main function of sucrose in the induction of tuberization was charged with sucrose itself, and directly related to it's trans-membrane transportion. The results also showed that StSUT1 and SuSy4 genes, which specifically expressed during the tuberization of potato plantles, could be induced by sucrose at transcriptional level, but was almost completely inhibited by pCMBS and partially inhibited by phloridzin treatment. The above preliminary results implied that...
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