[Responses of photosynthetic physiology and sap flow to the introduction of external dye in Populus ×euramericana cv. '74/76']. / 107æ¨å ‰åˆç”Ÿç†ä¸Žæ ‘å¹²æ¶²æµå¯¹å¤–æºæŸ“æ¶²å¯¼å ¥çš„å“åº”.

The exogenous liquid introduction technology is an effective way to produce the value-added poplar wood with excellent pattern color. This technology was used to add the various concentrated active red dyeing solution (0.2%, 0.4% and 0.6%) into target trees of six-year-old 107 poplar (Populus ×euramericana cv. '74/76'). The photosynthetic gas exchange parameter and sap flow rate were measured by Li-6400 photosynthetic instrument and TDP stem flowmeter, respectively. We analyzed the relationship between photosynthetic parameters, sap flow rate and dye absorption, and the effects of exogenous dye solution on the photosynthetic physiology and sap flow characteristics. The results showed that exogenous dyeing solution significantly inhibited flow rate of poplar trunks. The 0.2% concentrated liquid was far less effective than others (0.4% and 0.6%). The net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr) of poplars treated with different concentrated dyeing liquids were significantly lower than the control poplar. The intercellular carbon dioxide concentration (Ci) decreased first and then increased. The inhibitory effects of 0.4% and 0.2% concentrated dyeing solutions on photosynthesis were stronger than that of 0.6%. Dye absorption decreased with increasing dye concentration. The maximum liquid flow rate, Pn, gs and Tr were significantly negatively correlated with the dye content. The contents of chlorophyll (a+b), chlorophyll a and chlorophyll b in exogenous dyeing solution treatments were significantly lower than those of the control at the later stage. The concentration of dyeing solution and introduction time determined the amount of dye absorption. The dye solution 0.4%, which was introduced for three days, could ensure the appropriate dye absorption and reduce the inhibitory effect on the physiological activities of the poplar.

The first complete chloroplast genome sequences of Ulmus species by de novo sequencing: Genome comparative and taxonomic position analysis.

Elm (Ulmus) has a long history of use as a high-quality heavy hardwood famous for its resistance to drought, cold, and salt. It grows in temperate, warm temperate, and subtropical regions. This is the first report of Ulmaceae chloroplast genomes by de novo sequencing. The Ulmus chloroplast genomes exhibited a typical quadripartite structure with two single-copy regions (long single copy [LSC] and short single copy [SSC] sections) separated by a pair of inverted repeats (IRs). The lengths of the chloroplast genomes from five Ulmus ranged from 158,953 to 159,453 bp, with the largest observed in Ulmus davidiana and the smallest in Ulmus laciniata. The genomes contained 137-145 protein-coding genes, of which Ulmus davidiana var. japonica and U. davidiana had the most and U. pumila had the fewest. The five Ulmus species exhibited different evolutionary routes, as some genes had been lost. In total, 18 genes contained introns, 13 of which (trnL-TAA+, trnL-TAA-, rpoC1-, rpl2-, ndhA-, ycf1, rps12-, rps12+, trnA-TGC+, trnA-TGC-, trnV-TAC-, trnI-GAT+, and trnI-GAT) were shared among all five species. The intron of ycf1 was the longest (5,675bp) while that of trnF-AAA was the smallest (53bp). All Ulmus species except U. davidiana exhibited the same degree of amplification in the IR region. To determine the phylogenetic positions of the Ulmus species, we performed phylogenetic analyses using common protein-coding genes in chloroplast sequences of 42 other species published in NCBI. The cluster results showed the closest plants to Ulmaceae were Moraceae and Cannabaceae, followed by Rosaceae. Ulmaceae and Moraceae both belonged to Urticales, and the chloroplast genome clustering results were consistent with their traditional taxonomy. The results strongly supported the position of Ulmaceae as a member of the order Urticales. In addition, we found a potential error in the traditional taxonomies of U. davidiana and U. davidiana var. japonica, which should be confirmed with a further analysis of their nuclear genomes. This study is the first report on Ulmus chloroplast genomes, which has significance for understanding photosynthesis, evolution, and chloroplast transgenic engineering.