Nodule parenchyma-specific expression of the sesbania rostrata early nodulin gene SrEnod2 is mediated by its 3' untranslated region

AUTOR(ES)

Chen, R

RESUMO

The early nodulin Enod2 gene encodes a putative hydroxyproline-rich cell wall protein and is expressed exclusively in the nodule parenchyma cell layer. The latter finding suggests that the Enod2 protein may contribute to the special morphological features of the nodule parenchyma and to the creation of an oxygen diffusion barrier. The Enod2 gene of the stem-nodulating legume Sesbania rostrata (SrEnod2) is induced specifically in roots by the plant hormone cytokinin, and this induction occurs at a post-transcriptional level. Here, we characterize the cis determinant(s) in the SrEnod2 locus responsible for nodule parenchyma-specific expression and show that the 3' untranslated region (UTR) of the SrEnod2 gene is both required and sufficient for directing chimeric reporter gene expression in the nodule parenchyma of transgenic Lotus corniculatus plants. Moreover, we show that the SrEnod2 3' UTR does not act as a tissue-specific enhancer element. By conducting a detailed deletion analysis of the 5' and 3' SrEnod2 regions, we delimited the minimal promoter of the SrEnod2 gene, and it appears that the 5' flanking sequences are not essential for nodule parenchyma-specific expression. This finding is in contrast with the report that the 5' upstream region of the soybean Enod2 gene directs nodule parenchyma-specific expression, indicating that different mechanisms may be involved in regulating the expression of these two genes. We definitively demonstrate that the cis element(s) for tissue-specific expression is located within the 3' UTR of a plant nuclear gene.

Documentos Relacionados

• Posttranscriptional Regulation of the Sesbania rostrata Early Nodulin Gene SrEnod2 by Cytokinin.
• The early nodulin transcript ENOD2 is located in the nodule parenchyma (inner cortex) of pea and soybean root nodules.
• High-level expression of the rat whey acidic protein gene is mediated by elements in the promoter and 3' untranslated region.
• ENOD12, an early nodulin gene, is not required for nodule formation and efficient nitrogen fixation in alfalfa.
• Srchi13, a novel early nodulin from Sesbania rostrata, is related to acidic class III chitinases.