Developmental and Molecular Genetics of Embryogenesis in Arabidopsis

Meinke博士已经分离出200多个具有广泛发育异常的拟南芥胚胎突变体。他一直在绘制胚胎发生过程中具有基本功能的基因，并分析种子转化后产生的T-DNA插入突变体。提出的研究将继续对标记的胚胎突变体进行分子分析，并检查几种具有特别不寻常表型的未标记突变体。分子分析将集中在四个突变体上，其中侧翼序列已经恢复。详细分析将限于具有有趣表达模式的突变基因，与已知基因的序列同源性，或可以从现有cDNA文库中恢复的转录本。Meinke博士最近发现了一种新的同源突变体，它似乎在一个调控基因中存在缺陷，该基因的功能是激活广泛的胚胎特异性途径。突变胚胎是不正常的，偶尔胎生，不耐干燥，但可以在干燥前的培养中获救。由此产生的幼苗的表型与突变子叶部分转化为叶片的模型一致，并且该调控基因起着维持叶片和子叶区分的作用。该突变体没有标记，但值得详细分析，Meinke博士建议绘制基因图谱，为进一步表征这一有趣的突变体做准备。

Dr Meinke has isolated over 200 embryonic mutants of Arabidopsis thaliana with a wide range of developmental abnormalities. He has been mapping genes with essential functions during embryogenesis and an analyzing of T-DNA insertional mutants produced following seed transformation. The proposed research will continue a molecular analysis of tagged embryonic mutants and examine several untagged mutants with particularly unusual phenotypes. The molecular analysis will focus on four mutants in which flanking sequences have already been recovered. Detailed analysis will be limited to mutant genes with interesting patterns of expression, sequence homology to known genes, or transcripts that can be recovered from existing cDNA libraries. Dr. Meinke has recently identified a novel homeotic mutant that appears to be defective in a regulatory gene that functions to activate a wide range of embryo specific pathways. Mutant embryos are abnormal, occasionally viviparous, and desiccation intolerant, but can be rescued in culture prior to desiccation. The resulting seedlings have a phenotype consistent with a model that mutant cotyledons are partially transformed into leaves, and that this regulatory gene functions to maintain the distinction between leaves and cotyledons. This mutant is not tagged, but merits detailed analysis and Dr. Meinke proposes to map the gene in preparation to further characterization of this interesting mutant.