ABSTRACT. Characterization of defense-related genes is critical for breeding disease-resistant poplar varieties and for better management and control of leaf rust disease. In the present study, full-length cDNAs of five Populus szechuanica defense-related (PsDR) genes, pathogen-related protein 1 (PsPR1), β-1,3-glucanase (PsGns), thaumatin-like protein 1 (PsTLP1), thaumatin-like protein 2 (PsTLP2), and phenylalanine ammonialyase (PsPAL), were cloned from the leaves of P. szechuanica infected with Melampsora larici-populina (MLP). PsPR1 (728 bp), PsGns (1189 bp), PsTLP1 (929 bp), PsTLP2 (885 bp), and PsPAL (2586 bp) were predicted to encode 161, 347, 245, 225, and 711 amino acid residue-containing proteins with isoelectric points of 8. 53, 4.96, 4.51, 7.32, and 5.87, respectively. Moreover, the deduced PsDR proteins displayed more than 90% similarity to proteins from other Populus species. In response to the avirulent isolate, Sb 052 , and the virulent isolate, Th 053 , of MLP, the expression of PsDR genes was rapidly up-regulated in the leaves of P. szechuanica, peaked at 2 or 7 days post-inoculation (dpi), with levels in the incompatible interaction being higher than those in the compatible interaction. Meanwhile, the expression of PsDR genes (except for PsGns) was also differentially up-regulated at 3, 7, or 18 dpi in the petioles of the infected leaves, leaves next to the inoculated leaves, and in the top buds of the infected plants, respectively, compared to that at 0 dpi. These results suggest that these PsDR genes could play distinctive roles in the defense response of poplar against rust infection.

Mitochondrial DNA (mtDNA) heteroplasmy has been found to be commonly present in many organisms. However, the studies on the mitochondrial heteroplasmy within group of fishes are currently lacking. This specific purpose of this study was to investigate the mtDNA heteroplasmy in different organs within group of common carp. Based on cytochrome B (cyt B) gene, we amplified in a fragment of cytB gene from three tissues including liver, kidney and muscle of five individuals via polymerase chain reaction (PCR) with Pfu DNA polymerase, sequenced the amplified DNA fragments and compared mitochondrial heteroplasmy among these tissues. The result showed that the mean frequency of wild-type in muscle, liver and kidney was 54.4%, 56.8% and 68% respectively. Among the point mutations, frequency of substitution of G for A and C for T is 58.2%, 71.4% and 74.1% respectively in muscle tissues, liver and kidney.