Complete chloroplast genome sequence of Acacia crassicarpa (Fabaceae).

Acacia crassicarpa (Fabaceae), a nitrogen-fixing tree species, is critically important for coastal protection in southeast China. In this study, we report the complete chloroplast genome sequence of A. crassicarpa, with a length of 176,493 bp. It contains a pair of inverted repeats (IR 39,851 bp), a large single-copy region (LSC 91,869 bp), and a small single-copy region (SSC 4,922 bp). The complete genome comprises 138 genes, including 93 protein-coding genes, 37 tRNA, and 8 rRNA genes. Our phylogenetic analysis reveals that A. crassicarpa is closely related to A. podalyriifolia and A. dealbata.

[Carbon balance in an interplanting Pinus massoniana stand in subtropical eroded red soil region, China.] / 亚热带红壤侵蚀区马尾松不同套种模式生态系统碳平衡.

We measured the annual net biomass growth, carbon content of each component and soil heterotrophic respiration in four low-efficiency interplanting patterns, i.e., Pinus massoniana stands interplanting Myrica rubra, Sapindus mukurossi, Camellia oleifera and Gardenia jasminoides in Changting County, Fujian Province, with the aim to analyze the effects of interplanting patterns on carbon storage pattern and carbon balance of low-efficiency P. massoniana stand. The ranges of carbon content in different organs of M. rubra, S. mukurossi, C. oleifera, G. jasminoides and P. massoniana were 41.1%-50.1%, 42.2%-50.6%, 45.1%-48.9%, 44.7%-49.6% and 46.1%-51.9%, respectively. Carbon content of the same organ significantly differed among tree species. The pattern of P. massoniana interplanting M. rubra and S. mukurossi had the highest carbon stock and annual net carbon increase reserves, with values of 67.62-68.42 t·hm-2 and 9.21-9.45 t·hm-2·a-1, respectively. Followed by the lower pattern of C. oleifera, G. jasminoides, with values of 31.96-36.24 t·hm-2 and 4.09-4.16 t·hm-2·a-1, respectively. The P. massoniana pure forest was the lowest, with values of 17.01 t·hm-2 and 2.00 t·hm-2·a-1, respectively. Annual flux of soil heterotrophic respiration was following the order of P. massoniana interplanting M. rubra pattern (7.41 t·hm-2·a-1) > P. massoniana interplanting C. oleifera pattern (5.89 t·hm-2·a-1)> P. massoniana interplanting S. mukurossi pattern (5.86 t·hm-2·a-1) > P. massoniana interplanting G. jasminoides pattern (4.95 t·hm-2·a-1) > P. massoniana pure forest (2.45 t·hm-2·a-1). Annual net ecosystem carbon balance of P. massoniana interplanting M. rubra and S. mukurossi patterns were 2.04 and 3.27 t C·hm-2·a-1, showing a "carbon sink" pattern. The net carbon balance in the patterns of P. massoniana interplanting C. oleifera and G. jasminoides along with P. massoniana pure forest were -1.80, -0.80 and -0.45 t C·hm-2·a-1, which expressed a "carbon source" pattern. In the short-term, interplanting with M. rubra or S. mukurossi could improve the carbon income of the low-efficiency P. massoniana stand ecosystem.

De novo genome assembly of the stress tolerant forest species Casuarina equisetifolia provides insight into secondary growth.

Casuarina equisetifolia (C. equisetifolia), a conifer-like angiosperm with resistance to typhoon and stress tolerance, is mainly cultivated in the coastal areas of Australasia. C. equisetifolia, making it a valuable model to study secondary growth associated genes and stress-tolerance traits. However, the genome sequence is unavailable and therefore wood-associated growth rate and stress resistance at the molecular level is largely unexplored. We therefore constructed a high-quality draft genome sequence of C. equisetifolia by a combination of Illumina second-generation sequencing reads and Pacific Biosciences single-molecule real-time (SMRT) long reads to advance the investigation of this species. Here, we report the genome assembly, which contains approximately 300 megabases (Mb) and scaffold size of N50 is 1.06 Mb. Additionally, gene annotation, assisted by a combination of prediction and RNA-seq data, generated 29 827 annotated protein-coding genes and 1983 non-coding genes, respectively. Furthermore, we found that the total number of repetitive sequences account for one-third of the genome assembly. Here we also construct the genome-wide map of DNA modification, such as two novel forms N6 -adenine (6mA) and N4-methylcytosine (4mC) at the level of single-nucleotide resolution using single-molecule real-time (SMRT) sequencing. Interestingly, we found that 17% of 6mA modification genes and 15% of 4mC modification genes also included alternative splicing events. Finally, we investigated cellulose, hemicellulose, and lignin-related genes, which were associated with secondary growth and contained different DNA modifications. The high-quality genome sequence and annotation of C. equisetifolia in this study provide a valuable resource to strengthen our understanding of the diverse traits of trees.

[Simulation of vegetation landscape in Pingtan Island based on BP neural network model].

Taking GIS as technical platform and by using Matlab 7.0, the vegetation landscape in Pingtan Island was cut with 2 km x 2 km grid graph. The data of 50 quadrats were obtained. Forty-four of the 50 quadrates were used for model training, and the rest 6 were used for model checking. Fractal dimension, Shannon diversity index, and contagion index were selected as output data of the model, and the number of residential quarter, wind speed, and the distance from the coast were chosen as affecting factors. A BP neural network model of vegetation landscape in Pingtan Island was established, and was checked by error test. The results demonstrated that the major factors affecting the vegetation landscape spatial pattern and diversity in Pingtan Island were wind speed and the distance from the coast, and anthropogenic factors had greater effects on the spatial connection of vegetation landscape. The fitted results of the relationships between vegetation landscape and environmental and anthropogenic factors were basically accorded with the truth. The average error was 7.4%, and the minimum error was 0.2%, indicating that the model could be applied to quantitatively predict and simulate the vegetation landscape in Pingtan Island.

[Effects of fertilization on Casuarina equisetifolia seedlings total phenolics and extractable condensed tannin contents].

This paper studied the effects of nitrogen- and phosphorus fertilization on the total phenolics (TP) and extractable condensed tannin (ECT) contents in the branchlets of Casuarina equisetifolia seedlings, aimed to approach the nutrient effect on tannin production. Under nitrogen fertilization, the TP and ECT contents decreased significantly, which supported the hypotheses of carbon-nitrogen balance (CNB) and growth-differentiation balance (GDB), but the plant nitrogen content had less change, resulting in the decrease of TP/N and ECT/N ratios. Phosphorus fertilization had no significant effects on the TP and ECT production. With prolonged treatment time, the TP content in the branchlets of C. equisetifolia seedlings increased by 9.91% - 14.32%, but the ECT content decreased by 14.32% - 298.88%. The TP and ECT had opposite relationships with organic matters content, showing that different types of tannin had different biosynthetic pathways. However, both TP and ECT had no significant correlation with nitrogen content, and thus, the protein competition model (PCM) was not supported. Under nutrient-poor condition, the TP/N and ECT/N ratios were relatively high, which would be beneficial for the improvement of defense ability, the decrease of litter decomposition ratio and nutrient loss, and the maintenance of high productivity of C. equisetifolia plantations.

Antioxidant tannins from stem bark and fine root of Casuarina equisetifolia.

Structures of condensed tannins from the stem bark and fine root of Casuarina equisetifolia were identified using MALDI-TOF MS and HPLC analyses. The condensed tannins from stem bark and fine root consist predominantly of procyanidin combined with prodelphinidin and propelargonidin, and epicatechin is the main extension unit. The condensed tannins had different polymer chain lengths, varying from trimers to tridecamer for stem bark and to pentadecamer for fine root. The antioxidant activities were measured by two models: 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/ antioxidant power (FRAP). The condensed tannins extracted from C. equisetifolia showed very good DPPH radical scavenging activity and ferric reducing/ antioxidant power, suggesting that these extracts may be considered as new sources of natural antioxidants for food and nutraceutical products.

Seasonal changes in tannin and nitrogen contents of Casuarina equisetifolia branchlets.

Seasonal dynamics of total phenolics (TP), extractable condensed tannins (ECT), protein-bound condensed tannins (PBCT), fiber-bound condensed tannins (FBCT), total condensed tannins (TCT), and protein precipitation capacity (PPC) in young, mature and senescent branchlets of Casuarina equisetifolia were studied at Chishan Forestry Center of Dongshan County, Fujian Province, China. In addition, nitrogen contents of branchlets at the different developmental stages were also determined. The contents of TP and ECT, and PPC in young branchlets were significantly higher than those in mature and senescent branchlets through the season. However, PBCT contents were significantly higher in senescent branchlets than those in young and mature branchlets; FBCT fluctuated with season. Young branchlets had the highest N content, which decreased during branch maturity and senescence. The highest contents of TP and the lowest contents of TCT and N in young and mature branchlets were observed in summer. There was a significant negative correlation between TP and N contents. In contrast, TCT contents were positively correlated to N contents. Nutrient resorption during senescence and high TCT:N ratios in senescent branchlets are the important nutrient conservation strategies for C. equisetifolia.

[Energy characteristics of Casuarina equisetifolia ecosystem on coastal sand in Dongshan County, Fujian Province].

The study on the energy characteristics of Casurina equisetifolia community on red earth eolian sandy soil and homogeneous eolian sandy soil in Dongshan County of Fujian Province showed that the standing biomass and energy of Casurina equisetifolia community were 15 681.84 g x m(-2) and 317 795.31 kJ x m(-2) on red earth eolian sandy soil, and 5 129.87 g x m(-2) and 10 575.50 kJ x m(-2) on homogeneous eolian sandy soil, respectively. On homogeneous eolian sandy soil, the gross caloric value of the community ranged from 19.98 kJ x g(-1) to 21.39 kJ x g(-1), of which, dead branch was the highest while root was the lowest, and its percentage was 46.93% (truck) > 16.44%(root) > 13.92% (branch) > 12.28% (dead branch) > 5.87% (bark) > 3.90% (leaf) > 0.66% (fruit). The return amount of litter was 2061.77 kJ x m(-2) x yr(-1), and the net energy productivity was 12662.82 kJ x m(-2) x yr(-1). On red earth eolian sandy soil, the gross caloric value was 19.84 - 21.70 kJ x g(-1), among which, leaf was the highest while root was the lowest, and its percentage was 38.09% (truck) > 19.48% (branch) > 17.09% (root) > 16.86% (leaf) >6.83% (bark) > 0.88% (dead branch) > 0.77% (fruit). The returned amount of litter was 9070.47 kJ x m(-2) x yr(-1), and the net energy productivity was 31 298.70 kJ x m(-2) yr(-1). The standing biomass and energy of Casurina equisetifolia community were higher on red earth eolian sandy soil than on homogeneous eolian sandy soil, mainly because red earth eolian sandy soil had a thinner sandy layer (< 20 cm) and a stronger nutrient and water supplying ability.