García-Maroto F, Carmona M J
Departamento de Biotecnología, E.T.S. Ingenieros Agrónomos, Universidad Politécnica de Madrid, Avda, Complutense s/n, E-28040 Madrid, Spain.
Gene. 2001 Feb 21;264(2):163-71. doi: 10.1016/s0378-1119(01)00326-2.
The genomic organization of STDEFICIENS (STDEF), the potato orthologous gene to DEFICIENS (DEF) from Antirrhinum majus and APETALA3 (AP3) from Arabidopsis thaliana, has been investigated. Southern-blot analysis on genomic DNA from dihaploid potato lines, using 5'-gene specific probes, revealed polymorphisms that were consistent with the existence in potato of at least two copies of STDEF per haploid genome. This was confirmed by the detection of at least six different STDEF transcripts in the common tetraploid potato S. tuberosum. Genes for two of the STDEF loci, here designated as STDEF-1 and STDEF-2, have been identified as corresponding to the previously described pD13 and pD12 genomic clones, respectively (García-Maroto et al., 1993). In addition we have characterised the transcriptional STDEF unit. The main transcription start has been identified around 90 nt upstream of the putative initiation ATG codon, at a CAAATC motif, conserved in AP3. An additional transcription initiation site was detected by 5'-RACE analysis about 300 nt upstream of the main start, which has been confirmed by reverse transcriptase - polymerase chain reaction (RT-PCR) amplification from the longer transcripts. A comparison of the promoter regions for pD12, pD13 and AP3 indicates a similar overall structure, but reveals the existence of a great divergence between pD12 and pD13 in a promoter region that should contain important cis-regulatory elements. This raises the possibility of a differential regulation for the two STDEF genes.
已对马铃薯中与金鱼草的DEFICIENS（DEF）和拟南芥的APETALA3（AP3）直系同源的基因STDEFICIENS（STDEF）的基因组结构进行了研究。使用5'基因特异性探针，对双单倍体马铃薯品系的基因组DNA进行Southern杂交分析，结果显示多态性，这与马铃薯单倍体基因组中至少存在两个STDEF拷贝相一致。这在普通四倍体马铃薯S. tuberosum中检测到至少六种不同的STDEF转录本得到了证实。已确定两个STDEF基因座的基因，这里分别命名为STDEF-1和STDEF-2，分别对应于先前描述的pD13和pD12基因组克隆（García-Maroto等人，1993年）。此外，我们还对转录的STDEF单元进行了表征。已确定主要转录起始位点位于推定起始ATG密码子上游约90 nt处的CAAATC基序，该基序在AP3中保守。通过5'-RACE分析在主要起始位点上游约300 nt处检测到另一个转录起始位点，这已通过从较长转录本进行逆转录酶-聚合酶链反应（RT-PCR）扩增得到证实。对pD12、pD13和AP3启动子区域的比较表明总体结构相似，但揭示了在应包含重要顺式调控元件的启动子区域中pD12和pD13之间存在很大差异。这增加了两个STDEF基因存在差异调控的可能性。
