Abstract:

Leaf cDNA of 3 pest-resistant cotton crosses with remarkable different yield heterosis and their parents in 4 growth stages were amplified by DDRT-PCR (The mRNA Differential Display) with 45 primers combinations. The results were as follows: The proportions of genes differential expression between F1 and their parents were degressive tendency from square stage to boll stage in these crosses. The percentages of genes differential expression in the high heterotic cross were higher than those in the low heterotic crosses in four growth stages, which showing a closely relationship between gene differential expression and heterosis occurrence. The percentages of M3 (bands expressed only F₁) in the high heterotic crosses surpassed those in middle or low heterotic crosses at three earlier growing stages, which suggested M3 played an important role in yield heterosis occurrence. M4 (bands expressed in one parent and F1) was the main expression pattern in gene differential expression, but varied within narrow range in four growing stages, which indicated no remarkable correlation between yield heterosis and M4.

Key words: Pest-resistant cotton crosses, Heterosis, Growth stages, Gene differential expression