拟南芥xtc1突变体的图位克隆分析

Positional cloning of Arabidopsis xtc1 mutants

【目的】分析拟南芥xtc1突变体茎部表皮蜡的组分和含量,并鉴定导致xtc1突变体表型的基因。【方法】通过气相色谱法分析拟南芥xtc1突变体与Ler野生型茎部表皮蜡的成分;利用图位克隆确定突变基因位点,通过在拟南芥xtc1突变体中过量表达FATB基因,验证突变位点与FATB基因的关系。【结果】拟南芥xtc1突变体茎部表皮蜡总量约为Ler野生型的1/3,且各组分含量均明显减少;将突变基因定位在第1染色体顶端物理距离为80kb的2个标记T27G7-3和F22O13-1之间,该区域含有21个基因。T-DNA插入突变体观察及测序分析表明,xtc1突变体在At1g08510(FATB)基因的第1个外显子上产生14个碱基的缺失,导致翻译提前终止;在xtc1突变体中过量表达FATB基因可恢复xtc1突变体的正常表型。【结论】拟南芥xtc1突变体茎部表皮蜡含量减少,且突变基因为FATB基因。

【Objective】This research aimed to examine the chemical compositions and their contents of cuticular wax on the stems of Arabidopsis xtc1 mutant and identify the mutant gene that resulted in xtc1 phenotypes.【Method】The compositions of the cuticular wax on Arabidopsis xtc1 mutant and wild type Ler Arabidopsis were analyzed by gas chromatographic.The gene loci of mutation was identified by positional cloning,and the FATB gene was over-expressed in Arabidopsis xtc1 mutant to explore the relationship between the xtc1 loci and the FATB gene.【Result】Total wax load on stems of Arabidopsis xtc1 mutant was around 1/3 of that of wild type Ler and each composition was dramatically lower as well.xtc1 was located between two markers with 21 genes with a physical distance of 80 kb （T27G7-3 and F22O13-1） on chromosome 1.Observation of phenotypes of T-DNA insertion mutants and sequencing analysis revealed that xtc1 mutant carried 14 bp deletions in the first exon of At1g08510 （FATB）,which resulted in a premature stop codon.Overexpression of FATB gene in transgenic plants could rescue the phenotypes of xtc1 mutant.【Conclusion】FATB gene was the mutated gene that reduced wax load on xtc1 stems.