Elucidation of auxin signaling mechanism through identification of antiauxin resistant gene

在对生长素拮抗剂对氯苯氧异丁酸（PCIB）的抗性筛选中，发现了一个生长素拮抗剂抗性突变体（aar 1），该突变体对人工合成的生长素2，4-D也具有抗性。为了解生长素作用的分子机制，对aar 1突变体进行了遗传分析。aarl-1等位基因在4号染色体上的T6 G15区域具有多基因缺失。2，4-D反应性通过其中一个基因缺失的转化恢复，并且通过用RNAi构建体降低野生型中相同基因的表达来再现2，4-D抗性表型。该基因编码一种功能未知的小酸性蛋白（SMAP 1），存在于植物、动物和无脊椎动物中，但不存在于真菌或原核生物中。GFP融合分析表明SMAP 1定位于细胞核，其C端区域在功能上是重要的。综上所述，这些结果暗示了通过保守蛋白SMAP 1的新的生长素信号传导途径的存在。

An antiauxin resistant1 (aar1) mutant has been identified in a screen for resistance to the antiauxin, p-chlorophenoxy-isobutyric acid (PCIB) The aar1 was also resistant to synthetic auxin 2,4-D. To understand molecular mechanism of auxin action, genetic analyses of aar1 mutant were carried out. The aarl-1 allele harbors multi-gene deletions in T6G15 region on chromosome 4. 2,4-D responsiveness was restored by transformation with one of the genes missing and the 2,4-D-resistant phenotype was reproduced by decreasing the expression of the same gene in wild type with a RNAi construct. The gene encodes a small, acidic protein (SMAP1) with unknown function and present in plants, animals, and invertebrates but not in fungi or prokaryotes. GFP fusion analysis of SMAP1 suggested that SMAP1 is localized in nucleus and its C-terminal region is functionally important. Taken together, the results implied the presence of a novel auxin-signaling pathway through conserved protein SMAP1.