BcMF5, a pollen coat protein gene (PCP), from Brassica rapa. ssp. chinensis, involved in the transcription of different lengths of 3′-UTRs of PCPs

Abstract

Two transcript-derived fragments (GenBank accession number DN237907.1 and DN237908.1) with high homology accumulated in the wild-type flower buds of Chinese cabbage (Brassica rapa L. ssp. chinensis Makino) are isolated and investigated. By rapid amplification of cDNA ends (RACE), the full length cDNA of the two fragments were obtained. The alignment of their cDNA sequence showed that they are identical except for differences in a few nucleotides and should belong to the same gene, namely, B rassica rapa M ale F ertile 5 (BcMF5). The BcMF5 gene consists of 252 bp encoding a protein of 83 amino acids and is interrupted by an intron of 256 bp. Sequence blast analysis revealed that BcMF5 is a member of the pollen coat protein (PCP) gene family and shared a high homology to SLR-BP. In the process of 3′RACE, eight different lengths of 3′-UTR sequence are found from the wild type of the mmc mutant. Southern blot analysis showed that BcMF5 could be a single-copy gene in the Chinese cabbage genome, implying that eight different lengths of 3′-UTR sequences might come from the same gene and could be a result of multiple sites polyadenylation of 3′-UTRs of BcMF5. Based on sequence analysis, southern hybridization combined with RT-PCR, and northern hybridization, it was discovered that 3′-UTRs of BcMF5 contained some functional elements and their temporal and spatial expression patterns were different, but all strongly expressed in the stage IV and stage V flower buds of wild type. This indicate that different lengths of 3′-UTR may be involved in a regulation mechanism during the transcription of BcMF5.