ITEMS FROM SPAIN

 


UNIVERSIDAD POLITECNICA DE MADRID
Departamento de Biotecnologia, E.T.S. Ing. Agronomos.- C. Universitaria, 28040, Madrid, Spain.

A. Delibes, I. Lopez-Brana, S. Moreno-Vazquez, and C.M. Gonzalez-Belinchon.

UNIVERSITY OF LLEIDA AND
INSTITUTE FOR FOOD AND AGRICULTURAL RESEARCH AND TECHNOLOGY (UdL-IRTA)

Center of R&D, Rovira Roure 177, 25198 Lleida, Spain.

J.A. Martin-Sanchez, E. Sin, C. Martinez, and A. Michelena.

CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICA
Departamento de Proteccion Vegetal, Centro de Ciencias Medioambientales, Serrano, 115, 28006, Madrid, Spain.

M.D. Romero and M.F. Andres.

 

Changes in peroxidase gene expression in response to Heterodera avenae infection in a wheat/Aegilops ventricosa introgression line carrying the resistance gene Cre2. [p. 166-167]

The quasi-dominant, resistance gene Cre2 in H-93-8 wheat-Ae. ventricosa introgression line confers a high level of resistance to several European populations of cereal cyst nematode H. avenae, including the Spanish pathotype Ha71 (Delibes et al. 1993). An incompatible interaction between line H-93-8 and the nematode are determined by hypersensitive response, which is frequently preceded by the formation of active oxygen species (AOS). Plants possess both enzymatic and nonenzymatic antioxidant defence systems to counteract AOS under stress conditions. The antioxidant enzymes include peroxidase (PER, E.C.1.11.1.7), esterase (EST, E.C. 3.1.1.2), and superoxide dismutase (SOD, E.C. 1.15.1.1). Isoelectricfocusing isoenzyme analysis, 4 and 7 days-after-infection, revealed that PER, EST, and SOD activities increased in the resistant line H-93-8 in comparison with the susceptible control (Andres et al. 2001; Delibes et al. 2002; Montes et al. 2003). Nematode infection preferentially enhanced the activity of PER system, with a notable increase in cationic and anionic isozymes, as described in other incompatible reactions (Zacheo and Bleve-Zacheo 1993; Montes et al. 2004) and lent further support to the participation of lignification in the nonhost resistance.

In this work, PER mRNA transcripts, on infected and uninfected H-93-8 and a susceptible control, have been analyzed by Northern analyses using a PER probe obtained by PCR. RNAs were extracted from leaves and roots 4 and 7 days-after-infection. In the resistant line, 7 days postinoculation, a significant increase of peroxidase mRNA level was observed in roots at the nematode feeding site. No differential induction was detected in the susceptible control. Foliar mRNA levels were not affected by inoculation in any genotype. The root specific expression pattern of PER genes was determined by RT-PCR analysis, which the DNA second-strand was synthesized using a primer specific of PER. PCR products were cloned and sequenced, showing a high similarity to previously described cereal peroxidase genes. After a second round of RT-PCR with primers designed starting from the first RT-PCR sequences, differential mRNA transcripts from the nematode feeding site were obtained. Among the induced products, we found certain PER mRNA species that shown a C-terminal extension, which appears to target for vacuolar import as described in A. thaliana (Welinder et al. 2002). Peroxidase activity pattern and transcript accumulation profile suggests a role for peroxidase in resistance, probably in cell wall cross-linking.

In parallel to the described study, we are developing a new type of molecular markers for Cre2 and other resistance genes reported by our group in wheat. The H. avenae resistance from line H-93-8 was introduced into commercial wheat by backcrossing and selection. To assist the selection of resistance conferred by Cre2, we are currently searching markers based on LRR sequences described as major determinants of the specificity of resistance genes in plants. We are trying to obtain these markers by PCR using primers designed from NBS domain of resistance genes and transposons commonly inserted near rich gene regions. The novel markers will be scored as codominant SNP-based PCR markers as reported by Moreno-Vazquez et al. (2003).

Financial support. This work was supported by grant AGL2001-3824-CO4 from the Comision Interministerial de Ciencia y Tecnologia of Spain.

References.

Publications. [p. 168]