Abstract:

To provide an insight into the molecular basis of heterosis, differential display of mRNA was used to analyze the difference of gene expression between wheat ( Triticum aestivum L.) heterotic hybrid A, nonheterotic hybrid B and their parental inbreds in the primary roots. By using 5′ end random primers in combination with three one base anchored primers, it was found that 22.5% and 22.9% of 877 total displayed cDNAs were differentially expressed between hybrid A, B and their parents, respectively. Both quantitative and qualitative differences in gene expression between hybrids and their parental inbreds were obvious, indicating that the patterns of gene expression in hybrids alter significantly as compared to their corresponding parents. On the other hand, by using MADS box gene specific 5′ end primer for DDRT PCR, we found that nearly all of the displayed cDNA fragments were polymorphic between hybrids and their parents, and major difference occurred in qua litative level, in which hybrid specific expressed and silenced genes are the major two patterns, suggesting that MADS box gene may be important for manifestation of differential gene expression and wheat heterosis. In comparison with our previous results by using seedling leaves, it is indicated that differential gene expression between hybrids and parents is dependent on the tissues tested, and more differentially expressed genes were observed in the primary roots than in the seedling leaves. Therefore, it is concluded that the expressions of both randomly displayed cDNAs and transcription factor genes, such as MADS box, alter significantly between hybrids and their parents, which might be responsible for the observed heterosis.

普通小麦不同优势杂交种及其亲本苗期根系基因的差异表达

倪中福  孙其信^*  吴利民  解超杰

(中国农业大学作物学院,北京,100094)

为探讨小麦(Triticum aestivum L.)杂种优势形成的分子机理,选用普通小麦品种(系)3338、6554和2410TD及其强优势杂种A(3338×6654)和无优势杂种B(2410TD×6554),采用mRNA差异显示技术,对生长至三叶一心的根系(初生根)基因表达差异进行了比较研究.结果发现,小麦杂种一代苗期根系基因表达较亲本明显不同,表现为数量水平和质量水平上的差异,且差异表达基因的数目远高于我们以苗期叶片为材料的研究结果,表明小麦杂交种与其亲本间的基因差异表达与所研究的组织和器官有关.比较分析发现,在强优势杂种组合A中,超亲表达和偏高亲表达基因所占比例均明显高于无优势杂种组合B.以家族特异基因替代随机引物进行的差异显示结果表明,MADS-box家族基因在小麦杂交种和亲本苗期根系中存在着显著的表达差异,且差异表达类型以杂种特异表达和亲本基因在杂种一代沉默为主,说明MADS-box家族基因可能与小麦的杂种优势形成具有重要关系.对杂种和亲本基因表达差异与杂种优势的关系进行了分析和讨论.

关键词 mRNA差异显示 基因表达 杂种优势 小麦 初生根

*通讯作者

Key words: differential display, gene expression, heterosis, wheat, primary roots