Abstract

Two full-length and two partial cDNAs encoding sporamin A have been isolated from sweet potato tuberous roots. Sequence comparisons show that they are very similar with 94-98% homology at nucleotide level, and 80-88% at protein level. All four cDNAs possess multiple alternate polyadenylation signals in the 3' untranslated region ( 3'-UTR). Genomic Southern blot analysis indicates the presence of a sporamin multigene family in sweet potato. High levels of sporamin mRNAs were detected in developing tuberous roots, but they disappeared at the sprout-germinating stage. Differential expression of these genes was obvious as their mRNAs were present specifically in developing roots, rarely in stems and not in leaves.

中文摘要

本文中報告了四個 Sporamin cDNA 基因，其中有二個是全長的基因，另二個則不完整；此四個 cDNA 基因其序列與以往發表的皆不盡相同，但相似度則達 90%以上；根據 Gene Bank 的資料分析，四者皆屬 Sporamin A 亞群分子；從南方雜合的資料顯示，其含有相當多的子基因，北方轉印資料顯示，此基因在葉子部不表現，在莖部則微量存在，然而在塊根中則大量表現，故此基因被推論為扮演甘藷塊根中貯藏性蛋白質的功能。 關鍵詞: 多基因型，sporamin 基因群，貯藏性蛋白質，甘薯，3'-尾終端不轉譯區 (3'- UTR)。

Keyword: multigene family, sporamin, storage protein, sweet potato, 3'-untranslation region (3'-UTR).