Maintaining Genetic Resources of Peach Palm (<Emphasis Type="Italic">Bactris gasipaes</Emphasis> Kunth): The Role of Seed Migration and Swidden-fallow Management in Northeastern Peru

Knowledge of the effects of farmer practices on population genetic parameters of peach palm (Bactris gasipaes Kunth) is relevant to the improvement and conservation of the palm’s genetic resources. Microsatellite markers were used to assess genetic diversity and population structure of peach palm in swidden-fallow agroforestry systems in northeastern Peru. The study covered eight communities, comprising two study areas 160 km apart – one occupied by indigenous Amerindians and the other by mixed race campesinos. Simultaneous analysis of an ex situ peach palm germplasm collection provided a means to compare population genetic parameters. Farmers who were surveyed on seed selection practices for peach palm reported that an average of only four palms (4.3 for campesino and 1.5 for indigenous populations) were used to provide seed for the establishment of the forest gardens sampled. As expected, inbreeding coefficients observed within communities were relatively high (f = 0.105 − 0.210), however, observed heterozygosities within communities were also high (0.625–0.741). A metapopulation approach was used to describe migration within and among regions, implying a hierarchical structure of gene flow which maintains relatively high levels of genetic diversity. Seed migration was found to occur over longer distances (≤600 km) and at a higher frequency (46% of palms sampled) in the indigenous study area, and a proportionally greater number of alleles was found (49 vs. 43 over three loci) with twice as many private alleles occurring only in the indigenous populations. The farmers’ practice of preserving remnant palms through successive swidden generations may have contributed to the maintenance of alleles by reducing the severity of founder effects. Although the campesino study area exhibited a significant (20% of the variation; p < 0.01) isolation-by-distance relationship across 35 km distance, in general, both study populations had relatively limited genetic structure (θ = 0.012–0.03), which is believed to have resulted from the exchange of seeds over long distances and periods of time.     

Sedimentary characterization of Tagus estuarine beaches (Portugal)

Background, Aim and Scope  The distribution of sediments in estuarine beaches is controlled by the interactions between sediment supply, hydrodynamic processes and human intervention. The main purpose of this study is to characterize the sediments of Tagus estuarine beaches in order to understand their origin and to contribute to a better knowledge of the Tagus estuary sediment budget. Methods  Surface sediment samples were collected across beach profiles and sand grain size analysis was performed by dry sieving. Grain size statistics for the median (d₅₀) and standard deviation (SDM) were obtained using the Moment method. This study was complemented by a qualitative evaluation of the sediment composition. Cross-shore topographic surveys were conducted for selected sampling sites. Results  Tagus estuarine beach sediments are mainly composed of quartz sand particles which are fine-grained and well sorted near the mouth of the estuary and medium to coarse-grained and moderately sorted in the inner domain. Compositional results show evidence of active anthropogenic sediment sources, especially in the coarser fractions. Discussion  The analysis of the textural and compositional characteristics of beach sediments in the inner estuarine domain is compatible with local sedimentary sources, while a marine signature is present at the mouth and inlet channel sediments. In the inner domain, differences in the sedimentary processes are represented by the textural characteristics of the sediments, such as the sorting degree and the gravel content. Sediment characteristics also reflect human intervention in the system, with the introduction of anthropogenic and allochthonous particles and the mixture of sediments from different sources. Conclusions  The sediments of the inner Tagus estuarine beaches are derived from local Plio-Pleistocene outcrops while inlet and outer estuary beaches reveal a dominant marine source. Beach textural variability observed in the inner domain is not related to wave forcing gradients, but mainly to variations in the sedimentary processes along the estuarine margins and to human intervention. Results show that the Tagus estuarine beaches depended, almost exclusively, on sediment input from local sources until the last century. With increasing human occupation, sediment transfers became dominated by anthropogenically related activities mainly connected with the occupation of estuarine margins and dredging. Recommendations and Perspectives  Further studies should extend the present level of knowledge in what concerns sand transport patterns through additional compositional and geochemical analysis, and the development of new techniques in order to allow the quantitative evaluation of the impact of human activities on the sediment budget.     

基于模糊定权的模糊可信性约束二次规划模型

为了最大化黑河中游作物产生的经济效益和社会效益,采用模糊定权的方法将多目标效益转化为作物的综合效益权重,并将该权重应用于作物的水分生产函数中,对甘州区、临泽县和高台县的作物(小麦和玉米)进行水量优化配置.该模型为模糊可信性约束二次规划模型,模糊可信性约束中采用三角模糊数,可信性置信水平分别取0.5,0.6,0.7,0.8,0.9和1.0.以2011年的水量优化为例,优化后较优化前作物的配水量减少了3 701.25万m³,产量增加了1 291.28万kg,经济效益和社会效益分别提升了0.28亿元和0.18万人.另外,规划年2020年作物水量配置较现状年(2011年)的小麦和玉米的配水量分别减少了4.98%~5.24%和11.01%~12.07%,缺水情况得到改善.不同条件下的配水结果能够给决策者提供不同的方案.     

Production of mutants with high cold tolerance in spring canola (<Emphasis Type="Italic">Brassica napus</Emphasis>)

A major factor affecting spring canola (Brassica napus) production in Canada is killing frosts during seedling development in the spring and seed maturation in the fall. The objective of this study was to explore the possibility of producing spring canola lines with mutations that have altered biochemical pathways that increase cold tolerance. The approach was to generate UV point mutations in cultured microspores followed by chemical in vitro selection of individual mutant microspores or embryos resulting in measurable alterations to various biochemical pathways with elevated levels of key defense signaling molecules such as, salicylic acid (SA), p-Fluoro-d,l-Phenyl Alanine (FPA), and jasmonic acid (JA). In addition, since proline (Pro) is known to protect plant tissues in the cold-induced osmotic stress pathway, mutants that overproduce Pro were selected in vitro by using three Pro analogues: hydroxyproline (HP), azetidine-2-carboxylate (A2C); and, 3,4-dehydro-d,l-proline (DP). Of the 329 in vitro selected mutant embryos produced, 74 were identified with significant cold tolerance compared to their donor parents through indoor freezer tests at −6°C, and 19 had better winter field survival than winter canola checks. All chemically selected mutant doubled haploids with increased cold tolerance compared well with parent lines for all seed quality and agronomic parameters. Development of increased frost tolerant cultivars should allow for spring canola to be produced in western Canada without compromising seed quality.     

The inheritance of chemical phenotype in <Emphasis Type="Italic">Cannabis sativa</Emphasis> L. (III): variation in cannabichromene proportion

The mechanism that controls the proportion of cannabichromene (CBC), a potential pharmaceutical, in the cannabinoid fraction of Cannabis sativa L. is explored. As with tetrahydrocannabinol (THC) and cannabidiol (CBD), CBC is an enzymatic conversion product of the precursor cannabigerol (CBG). CBC is reported to dominate the cannabinoid fraction of juveniles and to decline with maturation. This ontogeny was confirmed in inbred lines with different mature chemotypes. A consistent CBC presence was found in early leaves from a diverse clone collection, suggesting that CBC synthase is encoded by a fixed locus. Morphological variants possessing a ‘prolonged juvenile chemotype’ (PJC), a substantial proportion of CBC persisting up to maturity, are presented. PJC is associated with a reduced presence of floral bracts, bracteoles, and capitate-stalked trichomes. Genetic factors causing these features were independent of the allelic chemotype locus B that was previously postulated and regulates THC and CBD synthesis and CBG accumulation. In contrast to previously described Cannabis chemotypes, the cannabinoid composition of PJCs showed plasticity in that reduced light levels increased the CBC proportion. The ability of PJC plants to enable the production of pharmaceutical raw material with high CBC purity is demonstrated.     

具有中国大豆遗传背景的7S与11S多亚基缺失型大豆新品系的创制

利用我国高油大豆品种东农47与日本引进多亚基缺失型育种材料日B,采用回交、三交的育种方法,综合系谱选择,通过SDS-PAGE技术分析亚基组成,在BC₁、BC₃及三交种F₈群体内,选育到(α+11S groupⅡa)-缺失型、(α′+11S groupⅡa)-缺失型、[(α′+α)+11S groupⅡa、Ⅱb]-缺失型、[(α′+α)+11S groupⅡa]-缺失型、[(α′+α)+11S groupⅡb+X₁X₂]-缺失型、[(α′+α)+11S groupⅡb]-缺失型和(α′+11S groupⅠ、Ⅱa)-缺失型共7种具有中国大豆遗传背景的7S球蛋白α′、α亚基与11S球蛋白groupⅠ(A_1aB_1b,A₂B_1a,A_1bB₂)、groupⅡa(A₄A₅B₃)和groupⅡb(A₃B₄)不同亚基缺失组合新种质。测定优良品系的综合农艺性状及氨基酸组成、含量,结果表明,与对照相比,各种缺失突变体的各种氨基酸组分含量普遍提高,蛋白总量普遍高于轮回亲本,精氨酸含量特别是游离精氨酸的含量大幅提高。其中亚基组成为(α+11S groupⅡa)-缺失型品系G2-2-3的17种氨基酸含量、氨基酸总量、蛋氨酸含量均显著高于轮回亲本东农47,特别是游离精氨酸含量高出7.27mg/g。以上结果表明,7S与11S多亚基缺失型优良品系在有效去除致敏蛋白的同时,可以提高大豆蛋白氨基酸含量, 改善大豆蛋白氨基酸组分配比。各种致敏蛋白缺失型大豆优良新品系的获得,大大丰富了我国蛋白质组分改良育种的种质基础。     

Soil compaction and forest floor removal reduced microbial biomass and enzyme activities in a boreal aspen forest soil

Soil enzymes are linked to microbial functions and nutrient cycling in forest ecosystems and are considered sensitive to soil disturbances. We investigated the effects of severe soil compaction and whole-tree harvesting plus forest floor removal (referred to as FFR below, compared with stem-only harvesting) on available N, microbial biomass C (MBC), microbial biomass N (MBN), and microbial biomass P (MBP), and dehydrogenase, protease, and phosphatase activities in the forest floor and 0–10 cm mineral soil in a boreal aspen (Populus tremuloides Michx.) forest soil near Dawson Creek, British Columbia, Canada. In the forest floor, no soil compaction effects were observed for any of the soil microbial or enzyme activity parameters measured. In the mineral soil, compaction reduced available N, MBP, and acid phosphatase by 53, 47, and 48%, respectively, when forest floor was intact, and protease and alkaline phosphatase activities by 28 and 27%, respectively, regardless of FFR. Forest floor removal reduced available P, MBC, MBN, and protease and alkaline phosphatase activities by 38, 46, 49, 25, and 45%, respectively, regardless of soil compaction, and available N, MBP, and acid phosphatase activity by 52, 50, and 39%, respectively, in the noncompacted soil. Neither soil compaction nor FFR affected dehydrogenase activities. Reductions in microbial biomass and protease and phosphatase activities after compaction and FFR likely led to the reduced N and P availabilities in the soil. Our results indicate that microbial biomass and enzyme activities were sensitive to soil compaction and FFR and that such disturbances had negative consequences for forest soil N and P cycling and fertility.     

Influence of non-cellulose structural carbohydrate composition on plant material decomposition in soil

The C mineralisation pattern during the early stage of decomposition of plant materials is largely determined by their content of different carbohydrates. This study investigated whether detailed plant analysis could provide a better prediction of C mineralisation during decomposition than proximate analysis [neutral detergent solution (NDF)/acid detergent solution (ADF)]. The detailed analysis included sugars, fructans, starch, pectin, cellulose, lignin and organic N. To determine whether differences in decomposition rate were related to differences in hemicellulose composition, the analysis particularly emphasised the concentrations of arabinose and xylose in hemicelluloses. Carbon dioxide evolution was monitored hourly in soil amended with ten different plant materials. Principal component and regression analysis showed that C mineralisation during day 1 was closely related to free sugars, fructans and soluble organic N components (R ² = 0.83). The sum of non-cellulose structural carbohydrates (intermediate NDF/ADF fraction) was not related to C mineralisation between days 1 and 9. In contrast, a model including starch and protein in addition to the non-cellulose structural carbohydrates, with the hemicelluloses replaced by arabinose and xylose, showed a strong relationship with evolved CO₂ (R ² = 0.87). Carbon mineralisation between days 9 and 34 was better explained by xylan, cellulose and lignin (R ² = 0.72) than by lignocellulose in the ADF fraction. Our results indicated that proximate analyses were not sufficient to explain differences in decomposition. To predict C mineralisation from the range of plant materials studied, we propose a minimum set of analyses comprising total N, free sugars, starch, arabinose, xylan, cellulose and lignin.     

METTL21C蛋白的序列特征、三维结构及分子进化

METTL21C蛋白作为甲基转移酶参与多种细胞进程的翻译后修饰,在生命活动中发挥重要的调控作用。从蛋白质信息数据库UniprotKB中选取36个不同代表物种的METTL21C蛋白作为研究对象,理化参数分析显示一级序列中氨基酸残基个数差异较大,平均为254个氨基酸残基,大多为偏酸亲水性蛋白。系统进化树显示36种METTL21C蛋白共分为哺乳类、爬行类、鸟类和鱼类4支,与物种的亲缘进化关系基本吻合。多序列比对和motif分析结果表明不同物种METTL21C蛋白的序列相似度较高,10个motif序列几乎覆盖了全长多肽链,大都含有motif 1～motif 5,但N端序列差异较大,在哺乳动物中包含特有的motif 7、motif 8和motif 10,而在多种鸟类中有大段序列缺失。结构对比分析发现不同物种METTL21C蛋白的空间构象绝大部分区域近乎完全重叠,仅少部分自由度较高的局部肽段有一定程度的差异,表明不同物种METTL21C在进化过程中一级序列有一定的差异,但是空间结构极为相似。以人METTL21C为蛋白质互作网络中心,直接相关蛋白质共11种,间接相关蛋白质共9种,说明METTL21C直接或间接参与多种细胞进程,调控机体的生命活动,为进一步深入研究METTL21C的生物学功能及其分子机制提供了理论基础。     

生物有机肥DNBF32对黑土中阿特拉津消减及土壤细菌群落结构的影响

试验研究生物有机肥DNBF32对除草剂阿特拉津在玉米田土壤中残留量及玉米生长情况的调控作用,并通过关注土壤细菌群落结构对DNBF32施用响应探讨DNBF32强化阿特拉津消减及调节玉米生长潜在作用机制.田间试验结果表明,DNBF32施用量为150 kg·hm-2以上时,玉米成熟期土壤中无阿特拉津检出.上述施用水平的DNB...