A Brassica napus gene family which shows sequence similarity to ascorbate oxidase is expressed in developing pollen. Molecular characterization and analysis of promoter activity in transgenic tobacco plants

Abstract

SummaryThe genomic clone named BplO contains a member of a small pollen-specific gene family of 9. napus. The expression of the BplO gene family is maximal in early binucleate microspores and declines considerably in mature trinucleate pollen. Homologues of the BplO genes are expressed in the pollen of other plant species. The pollen-specific expression of the gene contained in the genomic clone was confirmed in tobacco plants transformed with a chimeric BplO promoter/GUS construct. A promoter fragment of 396 bp is sufficient to direct a strong and correct spatial and temporal expression in transgenic plants. The BplO gene family codes for proteins of 62 kDa showing approximately 30% sequence identity to cucumber and pumpkin ascorbate oxidases (AAOs). However, the AAO active centres are not conserved in the BplO products, suggesting an evolutionary relationship but a different enzymatic activity for these proteins. Expression of a recombinant BplO protein in €. coli inhibits bacterial growth on minimal medium, suggesting the production of an enzymatically active polypeptide in bacteria. No AAO activity could be correlated with the expression of the recombinant protein. Moreover, substances affecting M O activity do not appear to influence the inhibitory activity of the protein produced in bacteria. However, as indicated by the rescue of bacterial growth in the presence of sodium bicarbonate or gaseous COB, the BplO protein activity could be modulated by COP levels.

Autophagy regulated by day length determines the number of fertile florets in wheat

“…, 1996), SERINE CARBOXYPEPTIDASE II‐3 PRECURSOR ( CP‐MII.3 ), a gibberellic acid‐induced gene that is involved in grain development in barley (Dal Degan et al. , 1994), and an ascorbate oxidase gene, which is expressed in developing pollen of Brassica napus (Albani et al. , 1992).…”

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“…Most data are available for late pollen promoters. These include petunia chiA [5], tomato LAT52 and LAT59 [4,6], rapeseed Bp10 [7], maize Zm13 [8,9] and tobacco NTP303 [10]. In Arabidopsis these include the TUA1 [11], AtPTEN1 [12], AtSTP6 [13], AtSTP9 [14] and the late vegetative cell-specific AtVEX1 [15] promoters.…”

Genetic analyses of signalling in flower development using Arabidopsis

“…Because the FIL2 gene is not expressed in a homeotic mutant, deficiens, and has a CArG box, the binding motif of MAD S box proteins, in its promoter region, it is strongly suggested that FIL2 is a target of the DEFICIENS gene product. The ascorbate oxidase gene of Brassica napus has a CArG box in its promoter [2]. This gene is specifically expressed in pollens at later stages of the maturation process.…”