ABSTRACT
Atmospheric nitrogen (N) deposition and increasing precipitation affect carbon sequestration in terrestrial ecosystems, but how these two concurrent global change variables affect xylem growth in trees (i.e., independently or interactively) remains unclear. We conducted novel experiments in central China to monitor the xylem growth in a dominant species (Quercus acutissima Caruth.) in response to N addition (CN), supplemental precipitation (CW) or both treatments (CNW), compared with untreated controls (C). Measurements were made at weekly intervals during 2014-15. We found that supplemental precipitation significantly enhanced xylem growth in the dry spring of 2015, indicating a time-varying effect of increased precipitation on intra-annual xylem growth. Elevated N had no significant effect on xylem increment, xylem growth rate, and lumen diameters and potential hydraulic conductivity (Ks) of earlywood vessels, but Ks with elevated N was significantly negatively related to xylem increment. The combination of additional N and supplemental precipitation suppressed the positive effect of supplemental precipitation on xylem increment in the dry spring of 2015. These findings indicated that xylem width was more responsive to supplemental precipitation than to increasing N in a dry early growing season; the positive effect of supplemental precipitation on xylem growth could be offset by elevated N resources. The negative interactive effect of N addition and supplemental precipitation also suggested that increasing N deposition and precipitation in the future might potentially affect carbon sequestration of Q. acutissima during the early growing season in central China. The effects of N addition and supplemental precipitation on tree growth are complex and might vary depending on the growth period and local climatic conditions. Therefore, future models of tree growth need to consider multiple-time scales and local climatic conditions when simulating and projecting global change.
Subject(s)
Quercus , Ecosystem , Nitrogen , Quercus/physiology , Trees , Xylem/physiologyABSTRACT
PREMISE OF THE STUDY: Microsatellite primers were developed to investigate population genetic structure in Lindera glauca (Lauraceae). METHODS AND RESULTS: Twenty-five microsatellite primers were developed and optimized for L. glauca using Illumina's Solexa sequencing technology. These novel primers were found to be polymorphic in nine wild L. glauca populations with 81 total alleles confirmed and genotyped via capillary gel electrophoresis. The total number of alleles, observed heterozygosity, and expected heterozygosity for each population ranged from one to four, from 0.00 to 0.90, and from 0.00 to 0.79, respectively. In addition, the 25 primers were tested in 10 additional individuals of the related species L. communis, and all but four markers showed good amplification results. CONCLUSIONS: This set of microsatellite primers is the first specifically developed for L. glauca and will facilitate studies of genetic diversity and evolution among populations of this species.
ABSTRACT
The Lindera glauca, an economically and ecologically important tree species, has emerged as a novel potential plant for the intensive studies of essential oil owing to its characteristic aroma and medicinal property in distinct tissues. However, the transcriptome information and molecular research on this species is still unknown to date. To reveal the formation and accumulation mechanism of essential oil in distinct L. glauca tissues, it is crucial to analyze transcriptome and to identify the full repertoire of potential unigenes involved in terpenoid biosynthesis. In this paper, the transcriptomes of the roots, sarcocarps, stems, leaves and kernels of L. glauca were analyzed for the first time by using short-read sequencing technology (Illumina). A total of 27.2GB valid reads (the average length=92.7bp) was obtained from distinct L. glauca tissues, and then assembled de novo into 264,831 unigenes by Trinity strategy (mean size=560.2bp). The resulting 98,141 unigenes (38%) of all the assembled unigenes were annotated in multiple public databases, of which 114 potential unigenes were identified to be involved in the terpenoid biosynthetic accumulation in L. glauca. Additionally, the differential expression profiles revealed 675, 697, 432, 1702 and 844 high tissue-specificity expressions of unigenes in the roots, sarcocarps, stems, leaves and kernels of L. glauca, respectively. Overall, these obtained comprehensive unigene resources will contribute to advance the research regarding the specific plant and more specifically discovery of genes participating in the terpenoid pathway and its regulation in specific tissues of the L. glauca, but also could help the understanding of the differential accumulation of secondary metabolites in distinct plant tissues.
