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。他一直在定位胚胎发生过程中具有必要功能的基因，并分析种子转化后产生的T-DNA插入突变体。这项拟议的研究将继续对标记的胚胎突变体进行分子分析，并检查几个具有特别不寻常表型的非标记突变体。分子分析将集中在已恢复侧翼序列的四个突变体上。详细的分析将限于具有有趣的表达模式的突变基因、与已知基因的序列同源性，或者可以从现有的cdna文库中恢复的转录本。Meinke博士最近发现了一个新的同源异型突变体，该突变体的一个调控基因似乎存在缺陷，该基因的功能是激活一系列胚胎特有的通路。突变的胚胎是不正常的，偶尔会胎生，干燥不耐受，但在干燥之前可以在培养中挽救。由此产生的幼苗具有与突变的子叶部分转化为叶片的模型一致的表型，并且该调控基因的功能是维持叶片和子叶之间的区别。这个突变体没有标记，但值得详细分析，Meinke博士建议绘制基因图谱，为进一步描述这个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.