OsWRKY22, a monocot WRKY gene, plays a role in the resistance response to blast.

With the aim of identifying novel regulators of host and nonhost resistance to fungi in rice, we carried out a systematic mutant screen of mutagenized lines. Two mutant wrky22 knockout lines revealed clear-cut enhanced susceptibility to both virulent and avirulent Magnaporthe oryzae strains and altered cellular responses to nonhost Magnaporthe grisea and Blumeria graminis fungi. In addition, the analysis of the pathogen responses of 24 overexpressor OsWRKY22 lines revealed enhanced resistance phenotypes on infection with virulent M.

Building a mutant resource for the study of disease resistance in rice reveals the pivotal role of several genes involved in defence.

In Arabidopsis, gene expression studies and analysis of knock-out (KO) mutants have been instrumental in building an integrated view of disease resistance pathways. Such an integrated view is missing in rice where shared tools, including genes and mutants, must be assembled. This work provides a tool kit consisting of informative genes for the molecular characterization of the interaction of rice with the major fungal pathogen Magnaporthe oryzae.

Characterization of WRKY co-regulatory networks in rice and Arabidopsis.

Background: The WRKY transcription factor gene family has a very ancient origin and has undergone extensive duplications in the plant kingdom. Several studies have pointed out their involvement in a range of biological processes, revealing that a large number of WRKY genes are transcriptionally regulated under conditions of biotic and/or abiotic stress. To investigate the existence of WRKY co-regulatory networks in plants, a whole gene family WRKYs expression study was carried out in rice (Oryza sativa).

Characterization of the model system rice--Magnaporthe for the study of nonhost resistance in cereals.

The best characterized form of resistance is gene-for-gene resistance. Less well characterized is nonhost resistance in which an entire plant species is resistant to an entire pathogen species. Here, different rice genotypes were inoculated with host and nonhost strains of Magnaporthe isolated from rice, wheat and crabgrass.

Effect of NaCl and mannitol iso-osmotic stresses on proline and free polyamine levels in embryogenic Fraxinus angustifolia callus.

With the aim to differentiate the ionic and osmotic components of salt stress, short and long-term changes in free polyamines and proline induced by iso-osmotic concentrations of NaCl (0.1 mol/L and 0.2 mol/L) and mannitol (0.

Potato virus X-induced gene silencing in leaves and tubers of potato.

Virus induced gene silencing (VIGS) is increasingly used to generate transient loss-of-function assays and has potential as a powerful reverse-genetics tool in functional genomic programs as a more rapid alternative to stable transformation. A previously described potato virus X (PVX) VIGS vector has been shown to trigger silencing in the permissive host Nicotiana benthamiana. This paper demonstrates that a PVX-based VIGS vector is also effective in triggering a VIGS response in both diploid and cultivated tetraploid Solanum species.

Regulated expression of a novel TCP domain transcription factor indicates an involvement in the control of meristem activation processes in Solanum tuberosum.

In this study, the aim was to determine whether TCP transcription factors are implicated in meristem activation in potato (Solanum tuberosum). By searching a database of potato EST sequences, with a sequence characteristically conserved in TCP domains, a potato tcp gene was identified. A BAC clone containing the tcp sequence was isolated and the genomic sequence was determined.

Changes in gene expression during meristem activation processes in Solanum tuberosum with a focus on the regulation of an auxin response factor gene.

A suppression subtractive hybridization approach (SSH) was used to generate a cDNA library enriched in clones representing genes that are up-regulated in the potato tuber apical bud on dormancy release. The sequences of cDNAs representing 385 different genes were determined. This study focuses on the characterization of one of these cDNAs.

Cuttings of the non-rooting rac tobacco mutant overaccumulate phenolic compounds.

The auxin and phenolic contents, as well as phenylalanine ammonia-lyase (PAL) activity, were determined in in vitro cultured shoots of the recalcitrant-to-root rac mutant of tobacco, and compared with wild-type shoots. The mutant and wild-type shoots showed similar auxin changes during the culture cycle, but with higher contents for the mutant. A transient peak of auxin (corresponding to the achievement of the rooting inductive phase) occurred at day 14 in both types of shoots, but earlier in the basal parts of the wild-type stems.