The promoter of the wheat puroindoline-a gene (<Emphasis Type="Italic">PinA</Emphasis>) exhibits a more complex pattern of activity than that of the <Emphasis Type="Italic">PinB</Emphasis> gene and is induced by wounding and pathogen attack in rice

Puroindolines form the molecular basis of wheat grain hardness. However, little is known about puroindoline gene regulation. We previously reported that the Triticum aestivum puroindoline-b gene (PinB) promoter directs β-glucuronidase gene (uidA) seed-specific expression in transgenic rice. In this study, we isolated a puroindoline-a gene (PinA), analyzed PinA promoter activity by 5′ deletions and compared PinA and PinB promoters in transgenic rice. Seeds of PinA-1214 and PinB-1063 transgenic plants strongly expressed uidA in endosperm, in the aleurone layer and in epidermis cells in a developmentally regulated manner. The GUS activity was also observed in PinA-1214 embryos. Whereas the PinB promoter is seed specific, the PinA promoter also directed, but to a lower level, uidA expression in roots of seedlings and in the vascular tissues of palea and pollen grains of dehiscent anthers during flower development. In addition, the PinA promoter was induced by wounding and by Magnaporthe grisea. By deletion analysis, we showed that the “390-bp” PinA promoter drives the same expression pattern as the “1214-bp” promoter. Moreover, the “214-bp” PinA promoter drives uidA expression solely in pollen grains of dehiscent anthers. The presence of putative cis-regulatory elements that may be related to PinA expression is discussed from an evolutionary point of view. By electrophoretic mobility shift assay, we showed that putative cis-elements (WUN-box, TCA motifs and as-1-like binding sites) whose presence in the PinA promoter may be related to wounding and/or the pathogen response form complexes with nuclear extracts isolated from wounded wheat leaves.     

Contrasted Microcolinearity and Gene Evolution Within a Homoeologous Region of Wheat and Barley Species

We study here the evolution of genes located in the same physical locus using the recently sequenced Ha locus in seven wheat genomes in diploid, tetraploid, and hexaploid species and compared them with barley and rice orthologous regions. We investigated both the conservation of microcolinearity and the molecular evolution of genes, including coding and noncoding sequences. Microcolinearity is restricted to two groups of genes (Unknown gene-2, VAMP, BGGP, Gsp-1, and Unknown gene-8 surrounded by several copies of ATPase), almost conserved in rice and barley, but in a different relative position. Highly conserved genes between wheat and rice run along with genes harboring different copy numbers and highly variable sequences between close wheat genomes. The coding sequence evolution appeared to be submitted to heterogeneous selective pressure and intronic sequences analysis revealed that the molecular clock hypothesis is violated in most cases.     

Isolation and sequence of cDNA encoding the soybean protease inhibitors PI IV and C-II

Two full-length (or nearly so) cDNA clones containing information for the protease inhibitors PI IV and C-II from soybean seeds were identified by means of a synthetic probe. DNA sequencing revealed that the two protease inhibitors are synthesized as precursors with a short peptide leader. The coding regions of the two clones show 80% homology, wheraes the 5 non-coding regions are 90% homologous. Homology of 75% is found in the region extending beyond the stop codons.     

Cloning and characterization of a cDNA encoding the wheat (Triticum durum Desf.) CM16 protein

A Triticum durum cDNA library prepared from developing endosperm (22 days after flowering (DAF)) was screened using synthetic oligonucleotide probes covering part of the CM3 and CM16 N-terminal protein sequences. A full-length cDNA clone (pTd78) encoding the CM16 protein (chloroform/methanol-soluble protein) was isolated and characterized. To our knowledge this is the first characterization of a clone coding for a wheat CM protein. The CM16 protein is synthesized as a preprotein with a signal peptide of 24 residues, the molecular weight of the mature protein being 13 438 Da. As other members of the cereal trypsin/-amylase inhibitor family, the CM16 protein contains 10 cysteine residues, their position being well conserved. In developing endosperm the highest level of CM16 mRNA was detected at mid-maturation.     

The thioredoxin h system: potential applications

The thioredoxin h system has the specific capability to reduce intramolecular disulfide bonds of proteins, thereby modifying their tertiary structure. It is involved in many processes: in the activation or deactivation of enzymes and enzyme inhibitors and in the germination process. This system can be used to improve the breadmaking quality of wheat by strengthening the dough. It can also decrease the epitope accessibility, then modifying the response of the IgE immune system. Transgenic barley and wheat have been created to confirm the functionality of the NADP-dependent thioredoxin h system.