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Septoria tritici blotch (STB), caused by the fungus Mycosphaerella graminicola (asexual stage: Septoria tritici), is one of the most economically important diseases of wheat worldwide. During the past decade 13 genes for resistance to STB have been identified and several molecular markers have been developed. However, analysis of resistance gene expression and utility for plant improvement programs would be increased if the resistance genes were isolated in a common susceptible background. To address this problem, a program was begun to backcross resistance genes Stb1-8 into two susceptible wheat cultivars. Work with genes Stb2, Stb3, Stb6 and Stb8 has proceeded the farthest. Resistance gene Stb3 is dominant, while Stb2 may be recessive. This will be the first report of recessive resistance to STB if confirmed. Molecular markers linked to the resistance genes are being validated in the backcross progeny and should provide the materials for efficient introgression of these genes into elite germplasm for future wheat improvement.

To better understand the mechanisms involved in aluminum toxicity and tolerance in plants, microarray technology was used to evaluate changes in gene expression in Arabidopsis thaliana under Al stress. With the use of Affymetrix Arabidopsis ATH1 Genechip, a comparison of RNA expression profiles was made between control and Al-treated Arabidopsis seedlings. A total of 256 genes were identified as Al-responsive. Ninety-four genes were shown to be up-regulated and 162 were down-regulated; comprising 1.1 % of the 24 000 Arabidopsis genes. Real-time RT-PCR was used to confirm the microarray data. The analysis showed that a large number of transcription factors and several putative signaling components were up-regulated by aluminum. Chloroplast structural and photosynthetic genes were, in general, down-regulated. A number of previously identified Al-responsive genes, e.g. GST, Auxin-regulated, Peroxidase, and Chitinase, were up-regulated by Al-stress, whereas Wali 3 and Wali 4 were down-regulated. We also identified several up-regulated genes involved in vacuolar signaling, sorting and docking. Three genes were also up-regulated by Al-stress, Ras GTP-binding protein, ABC-cassette binding, and the AtELP1 receptor genes, have previously been documented as responsive to drought and/or oxidative stress and may play important roles the detoxification of Al ions by transportation and storage into root vacuoles. Ultrastructural changes in the roots tips cells of Arabidopsis were evaluated using transmission electron microscopy and energy-dispersive X-ray analysis with scanning electron microscopy and results showed Al accumulation in the root tips of Arabidopsis.

This study was the first attempt to extract RNA from black willow (Salix nigra Marshall) that contains numerous secondary products and to examine the photosynthetic gene expression of black willow under a wide range of soil moisture regimes. Black willow cuttings were grown under control, continuous flooding, periodic flooding and periodic drought for 42 d. A modified lithium chloride precipitation method was used for RNA extraction. Results of real-time polymerase chain reaction showed reduced gene expression of oxygen evolving complex, large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenasse and ferredoxin on day 7 as well as the latter two on day 14 in response to flooding. Therefore, decreased expression of these three genes may have contributed to the observed reduced photosynthetic capacity in response to flooding.

Nine polymorphic microsatellite loci for the pied flycatcher (Ficedula hypoleuca),from a wild population in Spain are isolated and their variability escribed on 70 individuals. The number of alleles per locus ranged from 6 to 41 and observed heterozygosity ranged from 0.75 to 0.98. These markers are being used to study mating strategies in Ficedula hypoleuca iberiae.

Plant pathology literature provides ample evidence of growing knowledge of the biochemical, physiological, and genetic nature of host-pathogen interactions. Equally important, but less often studied, aspects of host-pathogen interactions are the complementary genetic changes that occur in the coevolution of host and pathogen populations. It is widely accepted that this coevolution of plants and their pathogens can be understood best in the context of integrated host-pathogen systems (e.g. 60). Pathogen population studies have been limited by a shortage of genetically well-defined host-pathogen systems based on easily scored genetic markers. Such markers are necessary to make use of the concepts of population genetics in improving our knowledge of host-pathogen population interactions. In particular, understanding the processes that drive genetic change in pathogen populations is essential to develop adequate and proper methods of disease control. Incorporating princi