Interactive effects of water management and liming on CH4 emissions and rice cadmium uptake in an acid paddy soil.

Rice agriculture is both an important source of the potent greenhouse gas methane (CH4) and a bioaccumulator of cadmium (Cd), which is hazardous to human health. Avoiding flooding during rice production is effective for reducing CH4 emissions, but it increases rice Cd uptake. Although lime application decreases Cd concentration in rice grains, it is not clear whether combining appropriate water management with liming can simultaneously reduce CH4 emissions and Cd uptake in rice paddies. Thus, a pot experiment was performed to investigate the interactive effects of water management (F: continuous flooding, FDF: flooding - midseason drainage - flooding, FDI: flooding - midseason drainage - intermittent irrigation) and lime application on CH4 emissions and rice Cd uptake in an acid paddy soil spiked with Cd. Results showed that neither water management nor liming significantly affected grain yield. Overall, liming reduced CH4 emissions by 42.2%. Compared to F, the FDF and FDI treatments reduced CH4 emissions by 43.5% and 54.2%, respectively. Liming reduced CH4 emissions by 32.6% under F, but with a greater decrease of 48.6% and 52.7% under FDF and FDI, respectively. Overall, liming reduced rice Cd uptake by an average of 47.3%. Compared to FDI, F and FDF significantly reduced Cd uptake by 84.0% and 75.1%, respectively, but there was no significant difference between F and FDF. Liming did not significantly affect Cd uptake under F and FDF, whereas liming reduced Cd uptake by 55.9% under FDI. These results suggest that maintaining flooding following midseason drainage can help in reducing rice Cd uptake, though slightly promoting CH4 emissions. Therefore, we recommend FDF combined with liming to mitigate CH4 emissions without increasing rice Cd uptake in acid paddy soils.

Analysis on single nucleotide polymorphisms of the PeTPS-(-)Apin gene in Pinus elliottii.

BACKGROUND: Resin-tapping forests of slash pine (Pinus elliottii) have been set up across Southern China owing to their high production and good resin quality, which has led to the rapid growth of the resin industry. In this study, we aimed to identify molecular markers associated with resin traits in pine trees, which may help develop marker-assisted selection (MAS). METHODS: PeTPS-(-)Apin gene was cloned by double primers (external and internal). DnaSP V4.0 software was used to evaluate genetic diversity and linkage disequilibrium. SHEsis was used for haplotype analysis. SPSS was used for ANOVA and χ2 test. DnaSP v4.0 software was used to evaluate genetic diversity. RESULTS: The full length PeTPS-(-)Apin gene was characterized and shown to have 4638 bp, coding for a 629-amino acid protein. A total of 72 single nucleotide polymorphism (SNP) loci were found. Three SNPs (CG615, AT641 and AG3859) were significantly correlated with α -pinene content, with a contribution rate > 10%. These SNPs were used to select P. elliottii with high α-pinene content, and a 118.0% realistic gain was obtained. CONCLUSIONS: The PeTPS-(-)Apin gene is not uniquely decisive for selection of plus slash pines with stable production, high yield, and good quality, but it can be used as a reference for selection of other resin-producing pines and other resin components.

Depression of the soil arbuscular mycorrhizal fungal community by the canopy gaps in a Japanese cedar (Cryptomeria japonica) plantation on Lushan Mountain, subtropical China.

Both canopy gaps (CG) and arbuscular mycorrhizal fungi (AMF) play key roles in seedling establishment and increasing species diversity in forests. The response of AMF to canopy gaps is poorly understood. To assess the long-term effects of canopy gaps on soil AMF community, we sampled soil from plots in a 50-year Cryptomeria japonica (L.f.) D. Don. plantation, located in Lushan Mountain, subtropical China. We analyzed the AMF community, identified through 454 pyrosequencing, in soil and edaphic characteristics. Both richness and diversity of AMF in CG decreased significantly compared to the closed canopy (CC). The differences of the AMF community composition between CG and CC was also significant. The sharp response of the AMF community appears to be largely driven by vegetation transformation. Soil nutrient content also influenced some taxa, e.g., the low availability of phosphorus increased the abundance of Acaulospora. These results demonstrated that the formation of canopy gaps can depress AMF richness and alter the AMF community, which supported the plant investment hypothesis and accentuated the vital role of AMF-plant symbioses in forest management.

Genome-Wide Discovery of DNA Polymorphisms in Mei (Prunus mume Sieb. et Zucc.), an Ornamental Woody Plant, with Contrasting Tree Architecture and their Functional Relevance for Weeping Trait.

Next-generation sequencing technologies provide opportunities to ascertain the genetic basis of phenotypic differences, even in the closely related cultivars via detection of large amount of DNA polymorphisms. In this study, we performed whole-genome re-sequencing of two mei cultivars with contrasting tree architecture. 75.87 million 100 bp pair-end reads were generated, with 92 % coverage of the genome. Re-sequencing data of two former upright mei cultivars were applied for detecting DNA polymorphisms, since we were more interested in variations conferring weeping trait. Applying stringent parameters, 157,317 mutual single nucleotide polymorphisms (SNPs) and 15,064 mutual insertions-deletions (InDels) were detected and found unevenly distributed within and among the mei chromosomes, which lead to the discovery of 220 high-density, 463 low-density SNP regions together with 80 high-density InDel regions. Additionally, 322 large-effect SNPs and 433 large-effect InDels were detected, and 10.09 % of the SNPs were observed in coding regions. 5.25 % SNPs in coding regions resulted in non-synonymous changes. Ninety SNPs were chosen randomly for validation using high-resolution melt analysis. 93.3 % of the candidate SNPs contained the predicted SNPs. Pfam analysis was further conducted to better understand SNP effects on gene functions. DNA polymorphisms of two known QTL loci conferring weeping trait and their functional effect were also analyzed thoroughly. This study highlights promising functional markers for molecular breeding and a whole-genome genetic basis of weeping trait in mei.