小麦杂种及其亲本苗期叶片家族基因差异表达及其与杂种优势关系的初步研究

为探讨小麦杂种优势形成的分子机理，以一套双列杂交组合的苗期叶片为材料，利用mRNA差异显示技术分析了杂种及其亲本间MADS－box、G－ box、Ser/Thr蛋白激酶、EIF－4A、ARF1基因家族共5类家族基因在杂交种和亲本之间的表达差异。并与杂种性状表现和杂种优势进行了相关分析。结果发现，除ARF1家族基因外，其余家族基因在杂种和亲本间存在显著的表达差异，差异表达类型可概括为4种：（1）双亲共沉默；（20单亲表达沉默；（3）杂种特异表达；（4）单亲表达一致。分析发现，MADS－box、G－box和EIF－4A家族基因在杂种和亲本间的差异表达模式相似，均以单亲特异表达和种特异表达类型所占比例最高。相关分析结果表明，以上所有家族基因的总体差异表达程度与所有性状的杂种表现均不相关，MADS－box家族基因中杂种特异表达类型与小穗数、单株产量和单穗产量杂种优势呈显著正相关，双亲共沉默类型与小穗数、千粒重和单穗产量杂种优势呈显著负相关，另外，EIF－4A家族基因中单亲表达一致型与单穗产量杂种优势呈显著正相，但双亲共沉默类型与小穗数和单穗产量杂种优势呈显著负相关，对于G－box基因家族而言，仅小穗数杂种优势和双亲共沉默类型成显著负相关，而蛋白激酶家族基因的各种差异类型与性状杂种优势的相关分析均不显著。这些研究表明，调控基因的差异表达与杂种优势形成有密切关系。

Relationship Between Differential Expression Patterns of Multigene Families and Heterosis in a Wheat Diallel Crosses

In order to understand molecular basis of heterosis, the patternsof differential gene expression of multigene families between wheat hybrids and their parents in seedling leaves were analyzed by using mRNA differential display. Relationships between differential gene expression patterns, heterosis and F1 hybrid performance were determined. Four patterns of differential gene expression were observed, which include: (1) bands observed in both parents but not in the F1; (2) bands occurring in only one parent but not in the F1 or the other parent; (3) bands detected in only the F1 but neither of the parents; (4) bands present in one parent and F1 but absent in the other parent. The analysis showed that patterns of differential gene expression were not correlated with the F1 hybrid performance for all the eight agronomic traits. However, differentially expressed fragments that occurred only in the F1 but neither of the parents were found to be positively correlated with heterosis. On the contrary, fragments observed in both parents but not in the F1 were negatively correlated with heterosis. It is concluded that the differential expression of regulatory genes plays an important role in heterosis.