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Cloning and identification of genes from the cambium of woody plants are important steps in the investigation of wood formation. In order to clone and identify the genes involved in wood formation, a cDNA library was constructed from the cambial tissue of Betula platyphylla Suk (birch). From the cDNA library, 2,878 high-quality ESTs were generated, representing 1,540 tentative unique genes (TUGs). Approximately 70% of the ESTs were matched to proteins in the NR database in GenBank and were grouped into 12 functional categories according to their functional annotation. Fifty TUGs potentially involved in wood formation, including the process of lignin biosynthesis, cell wall structure, cell wall polysaccharides synthesis or development regulation, were identified from the EST collection. The time course expression analysis of 13 wood formation related genes was further studied using RNA gel blot and semi-quantitative RT-PCR. The results showed that these genes were primarily expressed in tissue that was collected during two time periods, spring (26 April to 11 June) and later summer (30 July to 18 Sept). The bimodal expression curve of the genes indicates that both of these time periods are critical in wood formation in birch, and may be associated with cell wall expansion earlier in the year, and cell wall strengthening later in the year. [ABSTRACT FROM AUTHOR]

Plant peroxidases (PODs) have been ascribed a variety of biological functions, including hydrogen peroxide detoxification, lignin biosynthesis, hormonal signaling, and stress response. In the present study, ten POD genes, including three ascorbate peroxidases (class I PODs) and seven secretory peroxidases (class III PODs), were cloned from Tamarix hispida. The roles of the ten POD genes were addressed under different abiotic stress conditions, and gene expression profiles in roots, stems, and leaves were evaluated using real-time quantitative reverse-transcribed polymerase chain reaction. Our results showed that the relative abundance of the PODs was markedly different in roots, stems, and leaves, indicating that POD activity differs in these three organs. ThPOD1 and ThPOD8 were the most and least abundant, respectively, in all organs. The expression profiles in response to abiotic stresses were organ specific. All of the genes were highly induced by drought, salt, salt–alkaline, CdCl2, and abscisic acid (ABA) treatments in at least one organ. Five ThPOD genes were induced in roots, stems, and leaves under all of the studied stress conditions, indicating that they are closely associated with abiotic stress. Our results demonstrate that the ten plant peroxidases are all expressed in leaves, stems, and roots, that they are involved in different abiotic stress responses, and that they are controlled by an ABA-dependent stress signaling pathway. [ABSTRACT FROM AUTHOR]

Limonium bicolor, a halophytic species of flowering plant, thrives in saline-alkali soil, demonstrating that it has developed an efficient saline-alkali resistance system and has potential utility as a source of genetic determinants for saline-alkali tolerance. In this study, complementary DNA microarrays containing 1,240 clones of L. bicolor were constructed to have a better view of transcript expression in L. bicolor during saline-alkali (NaHCO3)-induced stress. We obtained transcript profiles of L. bicolor in response to NaHCO3 for 6, 24, and 48 h. A total of 149 transcripts were differentially regulated at least once under the conditions studied. Among these, at least six different patterns of transcript regulation could be distinguished. There were 111, 45, and 51 transcripts that were differentially regulated by NaHCO3 stress for 6, 24, and 48 h, respectively. Of these, nearly 35% were putative novel or functionally unknown genes, and the remainders were involved in a variety of functional areas such as defense, transport, metabolism, and transcription regulation. The microarray analysis demonstrated the complexity of, and differences in, gene expression patterns resulting from different NaHCO3 stress times. This study provides informative preliminary data and a starting point for more in-depth analyses of saline-alkali tolerance in L. bicolor. [ABSTRACT FROM AUTHOR]