Anaerobic induction of the maize<Emphasis Type="Italic"> GapC4</Emphasis> promoter in poplar leaves requires light and high CO<Subscript>2</Subscript>

The maize (Zea mays L.) glyceraldehyde-3-phosphate dehydrogenase gene 4 (GapC4) promoter confers anaerobic gene expression in tobacco (Nicotiana tabacum L.), potato (Solanum tuberosum L.) and Arabidopsis thaliana (L.) Heynh. Here we have investigated its expression in hybrid poplar (Populus tremula × P. alba). Our results show that the promoter is not expressed in leaves and stems under normoxic conditions while anaerobiosis induces reporter gene expression in leaves up to a level observed for the STLS-1 promoter from potato that is shown to confer leaf-specific gene expression in transgenic poplar. Anaerobic induction is cell autonomous and requires a CO₂ atmosphere and light. As in tobacco, the GapC4 promoter in poplar is wound inducible. The induction by CO₂ and light may reflect a natural situation because flooding, a natural cause of anaerobiosis, is often accompanied by high CO₂ concentrations in the floodwater. Our results show that the GapC4 promoter is suitable as an anaerobic reporter and as an inducible gene expression system in poplar.Abbreviations CaMV cauliflower mosaic virus - GapC4 glyceraldehyde-3-phosphate dehydrogenase gene 4 - GUS -glucuronidase - 4-MU methylumbelliferone - STLS-1 stem- and leaf-specific promoter 1     

The maize GapC4 promoter confers anaerobic reporter gene expression and shows homology to the maize anthocyanin regulatory locus C1

The cytosolic glyceraldehyde-3-phosphate dehydrogenase (GapC) gene family of maize is differentially expressed in response to anaerobic stress. While GapC1 and GapC2 are downregulated, GapC3 and GapC4 are anaerobically induced. We have sequenced and analyzed a 3073 bp promoter fragment of GapC4. The promoter confers anaerobic induction of a reporter gene construct in a transient gene expression system in maize. Deletion analysis of the GapC4 promoter revealed a 270 bp long DNA region required for anaerobic induction. This region contains sequence motifs resembling the cis-acting sequences of the anaerobically induced maize Adh1 and Adh2 genes. Furthermore, the 3073 bp GapC4 promoter fragment displays homology to long terminal repeats of maize retrotransposons and to the 3 region of the maize anthocyanin regulatory locus C1.     

Intron-specific stimulation of anaerobic gene expression and splicing efficiency in maize cells

Most of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes characterized in plants and algae to date have one intron very close to the 5 end of the gene. To study the functional relevance of some of these introns for gene expression we have analysed the influence of three 5 introns on transient gene expression of the anaerobically inducible maizeGapC4 promoter in maize cells. Under aerobic conditions, reporter gene expression is increased in the presence of the first introns of theGapC4 andGapC1 genes, and the first intron of the nuclear encoded chloroplast-specificGapA1 gene. In contrast, theGapC4 intron increases anaerobic gene expression above the level obtained for the intronless construct, while anaerobic expression of constructs harboring theGapA1 andGapC1 introns was similar to the anaerobic expression level of the intronless construct. Splicing analysis revealed that theGapC4 intron is processed more efficiently under anaerobic conditions, while no change in splicing efficiency is observed for theGapC1 and theGapA1 introns when subjected to anaerobic conditions. These results suggest that an increase in splicing efficiency contributes to the anaerobic induction of the maizeGapC4 gene.     

The TACPyAT repeats in the chalcone synthase promoter of Petunia hybrida act as a dominant negative cis-acting module in the control of organ-specific expression

Analysis of the expression of the GUS reporter gene driven by various regions of the Petunia hybrida chalcone synthase (chsA) promoter revealed that the developmental and organ-specific expression of the chsA gene is conferred by a TATA proximal module located between -67 and -53, previously designated as the TACPyAT repeats. Histochemical analysis of GUS reporter gene expression revealed that the organ-specific 67 bp promoter fragment directs the same cell-type specificity as a 530 bp promoter, whereas additional enhancer sequences are present within the more TATA distal region. Moreover, the region between -800 and -530 is also involved in extending the cell-type specificity to the trichomes of flower organs and of young seedlings. The mechanism by which the TACPyAT repeats modulate expression during plant development was studied by analysing the expression of the GUS gene driven by chimeric promoters consisting of the CaMV 35S enhancer (domain B, -750 to -90) fused to various chsA 5' upstream sequences. Detailed enzymatic and histochemical analysis revealed that in the presence of the TACPyAT module the CaMV 35S region only enhances GUS activity in those organs in which the chsA promoter is normally active. Furthermore, this analysis shows that enhancement in the presence of the CaMV 35S domain B is accomplished by increasing the number of cell types expressing the GUS gene within the organ, rather than enhancement of the chsA cell-type-specific expression within these organs. Deletion of the TACPyAT sequences in the chimeric promoter construct completely restores the well-documented CaMV 35S domain B cell-type specificity, showing that the TACPyAT module acts as a dominant negative cis-acting element which controls both organ and developmental regulation of the chsA promoter activity.     

高羊茅FaChit1基因启动子的功能分析

用含有不同长度FaChitl基因启动子区域与GUS基因融合构建植物表达载体pFaChitlP—I、pFaChitlP-Ⅱ以及pFaChitlP-Ⅲ并分别对烟草进行转化,经真菌激发子、干旱、机械损伤以及乙烯等多种胁迫处理后测定GUS活性。启动子缺失分析实验结果显示,真菌激发子对FaChitl基因启动子所介导的GUS诱导表达效果最强,而机械损伤只能微弱地诱导GL靥基因表达;FaChitl基因启动子-651bp以内的序列均能介导GUS基因的诱导表达,同时-935bp与-233bp之间的区域是该启动子响应真菌激发子、乙烯以及机械损伤胁迫所必需的。表明FaChitl启动子是一个多胁迫诱导型启动子。     

Light-dependent Anaerobic Induction of the Maize Glyceraldehyde-3-Phosphate Dehydrogenase 4 (GapC4) Promoter in Arabidopsis thaliana and Nicotiana tabacum

The maize glyceraldehyde-3-phosphate dehydrogenase 4 (GapC4)promoter confers strong and specific anaerobic gene expressionin tobacco (Nicotiana tabacum) and potato (Solanum tuberosum).Here we show that the promoter is also anaerobically inducedin Arabidopsis thaliana. Histochemical analysis demonstratesthat the promoter is anaerobically induced in roots, leaves,stems and flower organs. Surprisingly, the strong anaerobicinduction of the promoter is dependent on light and on the substitutionof oxygen with carbon dioxide. High carbon dioxide concentrationalone does not induce the promoter in the presence of oxygenand light. If anaerobic conditions are generated under completedarkness or if plants are submerged, no induction above backgroundis observed. When transgenic tobacco harbouring a GapC4 promoter–reportergene construct is analysed for light dependent anaerobic induction,the results are indistinguishable from those with arabidopsis.The implications for using the GapC4 promoter as an anaerobicreporter for monitoring alterations in the anaerobic signaltransduction pathway are discussed.