Study On Heterosis Of Hybrid Brassica Campestris L.ssp.pekinensis Olsson Baiyin 2 With Cdna-aflp

Heterosis, a widely existing biological phenomenon, has been successfully exploited on breeding of many plants and animals. Brassica crops is a kind of crops in which Heterosis was most successfully utilized. The scholars all over the world have made a lot of progress on heterosis of method and direction, and formed many theories. However, many aspects on heterosis are still unknown.In this study, the Baiyin 2 hybrid and their parents were experimental material, the differential gene expression between hybrid Baiyin 2 and its parents were analyzed with cDNA-AFLP. The material methods were as followed: collecting leaves separately in the seedling stage, the rosette stage and the heading stage, isolating the total RNA, synthesizing the Double-strained cDNA by using reverse transcriptase, and analyzing it with AFLP. Double-strained cDNA was digested with EcoRâ… and Mseâ… . The designed adaptors were specifically ligased to the ends of restriction fragments and pre-amplified. Then amplifing with 64 selective primers. The resulting products were size-fractionated on a 6% polyacrylamide sequencing type gel and silver staining.This study indicates that there are significant differences in the gene expression between hybrid and their parents. Four types of differential gene expression were detected between hybrid and their parents: (1)bands observed only in F1 but not in parents; (2)bands observed in both parents but not in F1; (3)bands observed in female parent and F1 not in male parent, bands observed in male parent and F1 not in female parent; (4)bands observed only in female parent but not in F1 and male parent, bands observed only in male parent not in F1 and female parent.The results also showed that 29 differentially expressed fragments were characterized different stages: 5 difference fragments in the seeding stage, 14 difference fragments in the rosette stage, 10 difference fragments in the heading stage. 19 difference fragments expressed in the hybrid, 3 difference fragments expressed in parents, 2 difference fragments expressed in female parent and 5 difference fragments expressed in male parent. The comparative analysis of 29 difference fragment's sequence discovered that 13 bands could find homologous sequence in the NCBI database, the other 16 fragments were not matched to any sequences in reported database, they probably belong to novel genes. The 13 homologous sequences participated in the following biological process: metabolism and cellular transport, etc. The comparative analysis of 29 difference fragment's protein sequence discovered that two gene fragments separately include the AP2/EREBP domain and the PPR domain. The two domains play important roles in the controlling of plant growth and development.This study applied cDNA-AFLP to analyze the differentially expressed genes in Brassica campestris L.ssp.pekinensis Olsson. The result will provide some evidence and information on heterosis molecular mechanism.