Heterosis-associated gene expression in early development

越来越多的证据表明，杂交种及其近交亲本之间的基因表达差异与杂种优势有关，而这些基因表达模式的改变与等位基因特异性沉默有关。了解这一现象的重要一步是了解哪些基因有助于识别差异表达基因。第一步将是构建玻璃微阵列，通过抑制减法杂交富集杂交种和相应自交系之间差异表达基因的cdna。由于表达模式是在受精后早期建立的，代表活性基因或储存的雌性配子转录本的cdna将包括在这些阵列中。对于杂交种及其近交亲本的表达谱分析，除了了解尽可能多的基因表达数据外，还将使用单基因微阵列，在受精后几天胚胎和胚乳发育的早期阶段进行微解剖，并用于杂交种和相应近交亲本之间的比较微阵列杂交。对互易F1杂交种的比较将提供一个系统来鉴定与亲本起源效应相关的基因。非常早期的发育阶段将被描述，以促进识别参与细胞命运决定和差异表达模式的构成的基因。对非授粉胚珠的进一步分析将整合母体组织，从而更全面地了解与籽粒相关的基因表达，这些表达谱将为克隆基因、功能分析和探索与杂种优势相关的基因调控网络提供基础。

There is emerging evidence that differential gene expression between hybrids and their inbred parents is associated with heterosis and that these altered expression pattern are connected with allele-specific silencing. An important step towards the understanding of this phenomenon would be the knowledge which genes facilitate the identification of differential expressed genes. The first step will be the construction of glass microarrays with cDNAs enriched for differential expressed genes between hybrids and the corresponding inbred lines by supression substractive hybridization. Because expression patterns are established early after fertilization cDNAs representing active genes or stored transcripts of female gametes will be included in these arrays. For expression profiling of hybrids and their inbred parents unigene microarrays will be used in addition to comprehend expression data of as much genes as Early stages of embryo and endosperm development, a few days after fertilization, will be microdissected and used for comparative microarray hybridization between hybrids and the corresponding inbred parents. Comparison of reciprocal F1 hybrids will provide a system to identify genes associated with parentof-origin effects. Very early developmental stages will be profiled to facilitate the identification of genes involved in cell fate determination and constitution of differential expression patterns. Additional profiling of non-pollinated ovules will integrate the mother tissue to provide a more comprehensive view on gene expression related to grain These expression profiles will serve as a basis to clone genes for functional analysis and exploration of gene regulatory networks associated with heterosis.