Lignin is a complex aromatic polymer of vascular plants that provides mechanical strength to the stem and protects cellulose fibres from chemical and biological degradation. 4-Coumarate: CoAligases (EC 6.2.1.12) are key enzymes for the biosynthetic pathway of monolignols which is an important complex aromatic polymer for lignin biosynthesis and tree growth. Recently, 4-coumarate: CoA ligase has been used as exogenous gene in transgenic plants to genetically modify the lignin biosynthesis pathway. Since most lignin is produced in the vascular cells, a tissue-specific-expressed promoter in the vascular cell would be important and useful to change and modify the content of lignin. Here we eport the existence of a promoter of GRP1.8 (the glycine-rich protein 1.8) in Sopho japonica L. (GenBank accession number AF250149) and studies on its function in transgenic tobacco. The promoter activity was analyzed in transgenic tobacco plants by histochemical staining of GUS gene expression driven by a 613-bp sjGRP1.8p promoter sequence. In sjGRP1.8p-GUS transgenic plants, intense GUS staining was detected in the xylem of the stem. To further investigate the regulation of the tissue-specific xpression of the 4CL1 gene, we analyzed the activity of the 4CL1 gene which is sense orientated with the sjGRP1.8p promoter in transgenic tobacco. The Pto4CL1 gene was expressed in the stem of ransgenic tobacco. The activity of the 4CL1 enzyme was increased 1-2-fold in the stem but not increased in the leaves of transgenic tobacco. In comparison with the control plants, the content of lignin was ncreased 25% in the stem but there was no increase in the leaves of transgenic tobacco.

ts ofelevated atmospheric CO. concentrations on the ecophysiological responses (gas exchange, chlorophyll a fluorescence, Rubisco activity, lear area development) as well as on the growth and biomass production of two poplar clones (i.e. Populus Irichoearpa×P deltoides clone Beaupre and P. ×euramericana clone Robusta) were examined under open top chamber conditions. The elevated CO2 treatment (ambient+350μmol mol-1) stimulated above-ground biomass of clones Rohusta and Beaupr6 after the first growing season by 55 and 38%, respectively-This lncreased biomass production under elevated CO2 was associated with a significant increase in plant height. the latter beingthe result of enhancedInternode elongation ratherthan alllncreased production of leaves or internodes Both an Increased leararea index (LAI) and a stimulated net Dhotosvnthesls per unit leaf contributed to a significantly higher stem biomassperunitleararea. andthustothelncreased above-ground biomassproduction underthe elevated CO2 concentratlons 1n both clones The larger LAl was caused by a larger individuaI leaf size and lear growth rate: the number ofleaveswas not altered bythe elevatedCO2 treatment The highernetlearphotosynthesiswasthe result of an 1ncrease 1n the hotochemical fmaximal chlorophyll fluorescence Fm and photochemical efficiency Fv/Fm)as well as m the biochemical (increased Rubisco activity) process capacities No significant difierences were found in dark respiration rate, neither between dongs nor between treatments, but specific leaf area significantly decreased under elevated CO2 conditions.

利用电子显微镜和光学显微镜中相差和微分干涉等技术对胡杨（Populus euphratica Oliv.）悬浮培养的细胞和试管苗的组织和细胞结构以及盐胁迫对其结构影响进行了研究。与毛白杨（P. tomentosa Carr.）相比，胡杨存在与 耐盐相关的结构，如根尖具有较发达的表皮和外皮层，根毛着生靠近根端；叶片输导组织不发达；细胞中线粒体和 质体较丰富。盐胁迫和渗透胁迫可使胡杨细胞质中的线粒体和质体变得更为丰富，质体中内含体增多，在细胞质 中和液泡内缘出现明显的嗜锇物质，在悬浮培养的细胞内表现出明显的丝状结构，细胞核变大，核仁明显。受到8 g/L NaCl胁迫的胡杨根尖分生细胞仍可维持正常的结构。在超微结构研究中还发现，胡杨细胞膜与细胞壁之间呈 齿状结合，说明了膜与壁之间结合的牢固性和稳定性，解释了胡杨细胞在胁迫中不易发生质壁分离的原因。

The ability of 4-coumarate: coenzyme Aligase promoter from Populus tomentosa (Pto4CL1p) to drive expression of the GUS reporter gene and 4-coumarate: coenzyme Aligase gene in tobacco has been studied using transgenic plants produced by Agrobacterium-mediated transformation. Intense GUS histochemical staining was detected in the xylem of stem in transgenic tobacco plants carrying the 1140 bp Pto4CL1p promoter. To further investigate the regulation function of the tissue-specific expression promoter, Pto4CL1p, a binary vector containing Pto4CL1p promoter fused with 4CL1 gene was transferred into tobacco. The activity of the 4CL1 enzyme doubled in the stems of transgenic tobacco but did not increase in the leaves. The content of lignin was increased 25% in the stem but there was no increase in the leaves of transgenic tobacco.