[Relationship between differential expression patterns of multigene families and heterosis in a wheat diallel crosses].

In order to understand molecular basis of heterosis, the patterns of 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.