中国棉花体细胞植株再生的基因型分析

我国开展棉花体细胞组织培养研究20多年来,已经成功的获得了戴维逊氏棉、雷蒙德氏棉、瑟伯氏棉、拟似棉、草棉、亚洲棉、海岛棉和陆地棉8个棉属的再生植株。其中陆地棉约占总数的70％,海岛棉约占20％。考查陆地棉栽培品种(系)的系谱亲缘关系,主要来源于斯字棉的材料约占26％、岱字棉约占23％、乌干达棉约占12％、珂字棉约占11％、爱字棉约占3％、福字棉约占1．5％。本文对我国再生植株品种(系)的差异进行了分析,并将开展棉花体细胞组织培养以来再生成功或研究利用的基因型加以整理,以期为进一步的研究提供参考。     

Identification and characterization of peptides binding AgEG1 from a phage display library

Endoglucanases are the main cellulolytic enzymes digestion as well as its good kinetic properties make it an attractive of Anoplophora glabripennis. Their high activities in cellulose target for development of cellulase inhibitors. In this study, random pepfide phage display technology was employed to identify peptides that bound the AgEG1, a member of endoglucanase isozymes. Phage clones with peptide LPPNPTK and XPP （X is residue T, L, A or H） motif frequently occurred in the selected phage population and showed a higher phage recovery than other clones. Peptide LPPNPTK was chemically synthesized and characterized tor its binding activities to AgEG1. The synthetic peptide exhibited high specificity for AgEG1. The peptide LPPNPTK has the potential to be developed into inhibitors of the endoglucanase of A. glabripennis.     

黑龙江省郭公虫科(鞘翅目)分类研究及一中国新记录种记述

本文报道了黑龙江省7种郭公虫科昆虫,包括1中国新记录种Orthrius striatulus （Motschlsky）.所有种类均列出了分布及成虫照片,中国新记录种还简要介绍了其鉴别特征.     

Genetic Diversity among the Germplasm Resources of the Genus <Emphasis Type="Italic">Houttuynia</Emphasis> Thunb. in China based on RAMP Markers

The genetic diversity of 70 Houttuynia Thunb. accessions from Sichuan, Chongqing, Guizhou and Jiangsu province in China were tested by using random amplified microsatellite polymorphism (RAMP) markers. All of the 43 primer combinations were found to amplify polymorphic products. A total of 304 products were amplified. Of which, 97.7 products were polymorphic. 6.9 polymorphic bands were amplified by each primer combination on average. The genetic similarity (GS) between the accessions within H. emeiensis and H. cordata were 0.660 and 0.575, respectively. The GS between two species was 0.525. The GS values between H. emeiensis and the H. cordata cytotype with the chromosome number of 36 was 0.559, higher than that between H. emeiensis and the cytotypes of H. cordata with other chromosome numbers. Within the species H. cordata, the genetic variation between cultivated and wild accessions was insignificant. The results of cluster analysis by using UPGMA method showed that all the tested accessions could be differentiated by RAMP markers, and classified into 11 groups. Many accessions with the same chromosome numbers could be classified together. The genetic diversity was more plentiful in mountainous and margin areas of the Sichuan Basin than at the bottom of the Basin and the highlands or hills surrounding it. It was concluded that there existed higher genetic diversity at the molecular level (RAMP markers) among the germplasm resources of the genus Houttuynia. The genetic relationships and phylogeny of the germplasm resources of Houttuynia were also discussed.     

Rice rhizodeposition and its utilization by microbial groups depends on N fertilization

Rhizodeposits have received considerable attention, as they play an important role in the regulation of soil carbon (C) sequestration and global C cycling and represent an important C and energy source for soil microorganisms. However, the utilization of rhizodeposits by microbial groups, their role in the turnover of soil organic matter (SOM) pools in rice paddies, and the effects of nitrogen (N) fertilization on rhizodeposition are nearly unknown. Rice (Oryza sativa L.) plants were grown in soil at five N fertilization rates (0, 10, 20, 40, or 60 mg N kg^?1 soil) and continuously labeled in a ¹³CO₂ atmosphere for 18 days during tillering. The utilization of root-derived C by microbial groups was assessed by ¹³C incorporation into phospholipid fatty acids. Rice shoot and root biomass strongly increased with N fertilization. Rhizodeposition increased with N fertilization, whereas the total ¹³C incorporation into microorganisms, as indicated by the percentage of ¹³C recovered in microbial biomass, decreased. The contribution of root-derived ¹³C to SOM formation increased with root biomass. The ratio of ¹³C in soil pools (SOM and microbial biomass) to ¹³C in roots decreased with N fertilization showing less incorporation and faster turnover with N. The ¹³C incorporation into fungi (18:2ω6,9c and 18:1ω9c), arbuscular mycorrhizal fungi (16:1ω5c), and actinomycetes (10Me 16:0 and 10Me 18:0) increased with N fertilization, whereas the ¹³C incorporation into gram-positive (i14:0, i15:0, a15:0, i16:0, i17:0, and a17:0) and gram-negative (16:1ω7c, 18:1ω7c, cy17:0, and cy19:0) bacteria decreased with N fertilization. Thus, the uptake and microbial processing of root-derived C was affected by N availability in soil. Compared with the unfertilized soil, the contribution of rhizodeposits to SOM and microorganisms increased at low to intermediate N fertilization rates but decreased at the maximum N input. We conclude that belowground C allocation and rhizodeposition by rice, microbial utilization of rhizodeposited C, and its stabilization within SOM pools are strongly affected by N availability: N fertilization adequate to the plant demand increases C incorporation in all these polls, but excessive N fertilization has negative effects not only on environmental pollution but also on C sequestration in soil.     

Impacts of nitrogen addition on the carbon balance in a temperate semiarid grassland ecosystem

Understanding carbon (C) cycling and sequestration in vegetation and soils, and their responses to nitrogen (N) deposition, is important for quantifying ecosystem responses to global climate change. Here, we describe a 2-year study of the C balance in a temperate grassland in northern China. We measured net ecosystem CO₂ exchange (NEE), net ecosystem production (NEP), and C sequestration rates in treatments with N addition ranging from 0 to 25 g N m^?2 year^?1. High N addition significantly increased ecosystem C sequestration, whose rates ranged from 122.06 g C m^?2 year^?1 (control) to 259.67 g C m^?2 year^?1 (25 g N). Cumulative NEE during the growing season decreased significantly at high and medium N addition, with values ranging from ?95.86 g C m^?2 (25 g N) to 0.15 g C m^?2 (5 g N). Only the highest N rate increased significantly cumulative soil microbial respiration compared with the control in the dry 2014 growing season. High N addition significantly increased net primary production (NPP) and NEP in both years, and NEP ranged from ?5.83 to 128.32 g C m^?2. The C input from litter decomposition was significant and must be quantified to accurately estimate NPP. Measuring C sequestration and NEP together may allow tracking of the effects of N addition on grassland C budgets. Overall, adding 25 or 10 g N m^?2 year^?1 improved the CO₂ sink of the grassland ecosystem, and increased grassland C sequestration.     

Archaea and bacteria respectively dominate nitrification in lightly and heavily grazed soil in a grassland system

To investigate the effects of stocking rates on nitrification activity and active nitrifying communities in a typical steppe grazing system, we conducted a laboratory incubation study using soil from a 10-year-old grassland gradient grazing experiment with sheep. A combination of molecular methods, such as DNA-based stable-isotope probing (DNA-SIP), real-time quantitative PCR, and high-throughput sequencing, was used to identify changes of nitrification activity and active nitrifying communities under different stocking rates (0 (SR0), 3 (SR3), 6 (SR6), and 9 (SR9) sheep per ha). The nitrification activity of soils was significantly increased by light grazing (SR3), while it was significantly decreased by heavy grazing (SR9). Nitrososphaera viennensis lineage of ammonia-oxidizing archaea (AOA) functionally predominated over ammonia-oxidizing bacteria (AOB) in nitrification in the SR3 soil, while the Nitrosospira cluster 3 of AOB was the major player in the SR9 soil. Therefore, stocking rates altered the distribution of active nitrifying communities by affecting soil chemical and physical conditions.     

Biochar amendment changes temperature sensitivity of soil respiration and composition of microbial communities 3 years after incorporation in an organic carbon-poor dry cropland soil

Topsoil samples were collected from plots in a dry cropland in the North China Plain 3 years after a single incorporation of biochar at 20 and 40 t ha^?1 and analyzed for abundances and composition of microbial community and for respiration under controlled laboratory conditions at 15, 20, and 25 °C. The addition of biochar generally reduced soil respirations at the three temperatures and the temperature sensitivity (Q₁₀) at 15–20 °C. Biochar amendment significantly increased bacterial 16S rRNA gene abundances and fungal ITS gene diversity and induced clear changes in their community compositions due to improvements in soil chemical properties such as soil organic C (SOC) and available N contents and pH. Illumina Miseq sequencing showed that the relative abundances of Actinobacteria, Gammaproteobacteria, Firmicutes, and Alternaria within Ascomycota, capable of decomposing SOC, were significantly decreased under biochar at 40 t ha^?1. The Q₁₀ values at 15–20 °C were significantly correlated with fungal diversity and dehydrogenase activity. Our results suggest that after 3 years a single biochar amendment could induce a shift in microbial community composition and functioning towards a slower organic C turnover and stability to warming, which may potentially reduce soil C loss in dryland under climate warming in the future.     

Soil N transformation mechanisms can effectively conserve N in soil under saturated conditions compared to unsaturated conditions in subtropical China

The connection between moisture and nitrogen (N) transformation in soils is key to understanding N losses, particularly nitrate (NO₃^?) losses, and also provides a theoretical framework for appropriate water management in agricultural systems. Thus, we designed this study to provide a process-based background for management decision. We collected soil samples from the long-term field experiment in subtropical China, which was designed to examine tobacco and rice rotations under a subtropical monsoon climate. The field experiment was established in 2008 with four treatments: (1) no fertilization as control; (2) N, phosphorus (P), and potassium (K) fertilizers applied at recommended rates; (3) N fertilizers applied at rates 50% higher than the recommended amounts and P and K fertilizers applied at recommended rates; and (4) N, P, and K fertilizers applied at recommended rates with straw incorporated (NPKS). Soil samples were collected during the unsaturated tobacco-cropping season and saturated rice-cropping season and were incubated at 60% water holding capacity and under saturated conditions, respectively. Two ¹⁵N tracing treatments (¹⁵NH₄NO₃ and NH₄¹⁵NO₃) and a numerical modeling method were used to quantify N transformations and gross N dynamics. Autotrophic nitrification was stimulated by N fertilizer both under unsaturated and saturated conditions. The rate of NO₃^? consumption (via immobilization and denitrification) increased under the NPKS treatment under saturated conditions. Secondly, the rates of processes associated with ammonium (NH₄⁺) cycling, including mineralization of organic N, NH₄⁺ immobilization, and dissimilatory NO₃^? reduction to NH₄⁺, were all increased under saturated conditions relative to unsaturated conditions, except for autotrophic nitrification. Consequently, NO₃^?-N and NH₄⁺-N concentrations were significantly lower under saturated conditions relative to unsaturated conditions, which resulted in reduced risks of N losses via runoff or leaching. Our results suggest that under saturated conditions, there is a soil N conservation mechanism which alleviates the potential risk of N losses by runoff or leaching.