ROLES FOR SUGAR SIGNAL DURING TUBEROUS ROOT DEVELOPMENT AND REGULATION OF SUGAR SIGNAL BY INVERTASE IN SWEET POTATO.

为了研究细胞壁结合型转化酶在甘薯中的作用，我从甘薯块根中克隆了一个细胞壁结合型转化酶的cDNA，命名为IbCIN 1。IbCIN 1全长1746 bp，开放阅读框架，编码577个氨基酸残基。推导的氨基酸序列显示了典型的细胞壁结合型转化酶的特征，包括一个果糖苷酶基序和一个半胱氨酸催化位点。IbCIN 1在幼根、块根和块根中表达，在发育中的叶片、成熟叶片、叶柄和匍匐茎中不表达。IbCIN 1在块根发育过程中表达下降。IbCIN 1的mRNA水平被6-苄氨基嘌呤升高，但受糖的影响很小。原位定位结果表明，IbCIN 1基因在块根中优先表达于胚盘皮层。这些结果表明，IbCIN 1是重要的供应碳源的块根的外胚层或分化的外胚层。

To study roles of cell wall-bound invertase in sweet potato, I cloned a cDNA for cell wall-bound invertase, designated IbCIN1, from tuberous root of sweet potato. IbCIN1 contained an open reading frame of 1746 bp encoding a polypeptide of 577 amino acid residues. The deduced amino acid sequence showed typical features of the cell wall-bound invertases, including a fructosidase motif and a crysteine catalytic site. IbCIN1 was expressed in young root, tuberous root and root from tuberous root whereas no expression was observed in developing leaf blade, mature leaf blade, petiole and stolon. Expression of IbCIN1 decreased during developing of tuberous root. The level of mRNA for IbCIN1 was elevated by 6-benzylaminopurine, but was little affected by sugar. In situ localization of the mRNA revealed that, IbCIN1 is expressed preferentially in the phelloderm of tuberous root. These results suggest that IbCIN1 is important for supplying a carbon source to the phelloderm of tuberous root or differentiation of the phelloderm.