Abstract: The patterns of gene differential expression in roots and leaves between CRI47 and its parents at seedling stage were analyzed by using DDRT-PCR, and the relationship between the hybrid yield traits and patterns of gene expression was also studied. The main results were as follows: (1) Differential expression bands in roots and leaves accounted for 38.8% and 65.2% of their total numbers of detected bands,respectively. The differential expression bands in leaves were richer than those in roots, which explained that some useful genes to heterosis maybe begin to express in seedling leaves. (2) Four types of differential expression were detected between the hybrid and its parents: I. Bands expressed in both parents but not in F1; II. Bands expressed in one parent but not in F1 and another parent; III. Bands expressed only in F1 but not in both parents; IV. Bands expressed in one parent and F1 but not in another parent. Percentages of the four types accounted for 6.5%, 10.6%, 6.5% and 15.2% in roots and 4.4%, 17.9%, 15.1% and 27.8% in leaves, respectively. The tendency of proportion in four types in roots and leaves was consistent, which indicated the type of bands expressed only in one parent and F1 played main role in CRI47 yield. (3) Increase of boll number per plant was the main cause of high yield formation in CRI47, which also indicated the type of bands expressed only in one parent and F1 contributed to CRI47 yield. These results showed that there were closely relationship between differential expression genes and heterosis at seedling stageof cotton.

Key words: CRI47, Roots, Leaves, DDRT-PCR, Heterosis