美科学家完成大豆基因组测序

约一万年前,农业的出现标志着人类进化史的显著变化,而农业社会人类饮食方式的改变可能对新石器世代人们的遗传结构有着及其重要的影响.在中国南部及其临近地区人群基因组中,乙醇脱氢酶第47位氨基酸多态性(ADH1B*47His)普遍存在.     

一个与水稻条纹叶枯病抗性基因紧密连锁的分子标记的鉴定

针对水稻条纹叶枯病粳型(Oryza sativa ssp. japonica)抗源镇稻88尚无可供育种利用的分子标记的现状,以镇稻88和感病品种武育粳3号配组构建F2作图群体。在采用单分蘖鉴定和苗期接种鉴定方法对F2群体和F2:3家系分别进行抗性遗传分析的基础上,通过标记分析表明,RAPD标记OPO11与镇稻88中抗性基因紧密连锁,表现为共分离。使用该标记对徐稻3号等3个镇稻88衍生抗性品种进行分析,结果表明,RAPD标记OPO11可应用于镇稻88与武育粳3号组合及其衍生组合的分子标记辅助选择。     

华东地区家鸭资源群体的遗传结构分析

本实验通过微卫星标记技术对我国华东地区9个家鸭资源群体（微山麻鸭、巢湖麻鸭、绍兴鸭、高邮鸭、大余鸭、金定鸭、连城白鸭、莆田黑鸭、山麻鸭）的遗传结构进行了评估。结果表明：9个品种的平均杂合度都较高，最低的为金定鸭，最高的为山麻鸭，杂合度范围为0.5137～0.6055，群体平均杂合度为0.5523，反映了各鸭种的杂合度都较高，遗传多样性丰富；华东区各鸭种间存在较大的遗传分化，25.65%的遗传变异来源于品种间的差异，更进一步反映了各品种具有本品种特征特性的多样性；通过计算DA遗传距离发现各群体的遗传距离较远，分化时间较长；NJ聚类结果将华东区家鸭资源聚为4类，NJ的聚类结果分析与几个鸭品种的地域分布和经济用途有一定关系。研究结果充分反映了华东区家鸭资源的遗传结构，对促进资源优势向经济优势的转化具有重要科学意义。     

燕山南麓夏季降水对东亚夏季风变化的响应

利用燕山南麓1951-2005年夏季降水资料和NCEP/NCAR高度场、风场资料,采用趋势分析、小波变换、突变检验等方法,对燕山南麓夏季降水规律和东亚夏季风变化进行了分析。结果发现:(1)燕山南麓夏季降水从1980年以来呈减少趋势,在1996年发生了突变,近年减少更加显著。线性减少趋势显著,平均每10 a减少29mm。(2)燕山南麓夏季降水存在10 a的变化周期,东亚夏季风存在11 a的变化周期,二者变化周期基本一致。降水的10 a周期显著,东亚夏季风11 a周期不太显著。(3)强夏季风年,蒙古地区低气压显著降低,蒙古上空低槽活动频繁,极涡明显变弱,燕山南麓夏季降水偏多。弱夏季风年,蒙古地区低气压明显减弱,蒙古上空低槽活动较少,极涡显著加深,燕山南麓夏季降水偏少。(4)燕山南麓夏季降水减少是对东亚夏季风减弱和对应的中高度大气纬环流变化的响应。     

Methane flux characteristics in forest soils under an East Asian monsoon climate

Methane (CH₄) uptake by soil can possibly be suppressed more in regions with heavy summer precipitation, such as those under the East Asian monsoon climate, as compared to that in regions with a dry summer. In order to determine how precipitation patterns affect seasonal and spatial variations in CH₄ fluxes in temperate forest soils, such fluxes and selected environmental variables were measured on different parts of a hill slope in a cypress forest in central Japan. On the upper and middle parts of the slope, CH₄ uptake was observed throughout the year, and the uptake rates increased slightly with soil temperature and decreased with soil water content. The CH₄ flux predicted using data for the middle and upper parts of the slope ranged from −1.12 to −0.83 kg-CH₄ ha⁻¹ y⁻¹ (i.e. CH₄ uptake by soil) and from −2.30 to −2.04 kg-CH₄ ha⁻¹ y⁻¹, respectively. In contrast, in the relatively wet lower part of the slope near an in-stream wetland, large CH₄ emissions (>2 mg-CH₄ m⁻¹ d⁻¹) were observed during the rainy summer. In this wetter plot, the soil functioned as a net annual CH₄ source in a rainy year. Hence the variation in CH₄ flux with a change in soil water conditions and soil temperature on the lower part of the slope contrasted to that on the upper and middle parts of the slope. The predicted CH₄ flux for this lower plot ranged from −0.45 kg-CH₄ ha⁻¹ y⁻¹ in a dry year to 1.80 kg-CH₄ ha⁻¹ y⁻¹ in a rainy year. Our results suggest that consideration of the soil water conditions across a watershed is important for estimating the CH₄ budgets for entire forest watershed, particularly in regions subject to a wet summer.     

东亚季风环流对华北地区降水蒸发差的影响

采用趋势分析和突变检验等统计方法,分析了华北地区降水蒸发差的变化趋势和东亚地区不同等压面高度上风场、气压场、湿度场和温度场的年代际差异.结果表明,华北地区降水蒸发差主要受降水量变化的影响,1977年前后发生了由增到减的年代际转折;华北地区降水蒸发差与亚洲经向环流指数呈正相关、与纬向环流指数呈负相关关系,相关显著性具有阶段性特征;1977年前后,东亚地区850hPa高度上西南季风强度由强变弱,中高纬度气压系统由距平低压转变为距平高压,平均相对湿度场分布由正距平转变为负距平,1000hPa高度平均温度场增温显著.分析认为,东亚地区夏季风强度减弱、热带水汽输送量减少,致使华北降水减少是1978年以来华北地区降水蒸发差持续减小的主要原因;而东亚地区冬季风强度减弱,影响极地冷空气南下,引起华北气温升高、蒸发增强则进一步加剧了华北地区的干旱化程度.东亚季风环流对华北降水和气温的共同作用,导致华北地区降水蒸发差发生年际和年代际变化.     

区域气候变化对华东地区水稻产量的影响

为揭示区域气候变化对华东地区水稻产量的影响以及水稻产量波动的原因,采用功率谱和交叉小波变换方法分析了近59a来华东地区水稻产量、平均气温和降水量的时频变化特征以及水稻产量与区域气候变化之间的关系。结果表明：华东地区水稻产量和区域气候均存在年际和年代际尺度变化周期。气象产量与生育期平均气温以正相关关系为主,局部时域中也存在不同频率尺度的负相关;主要表现为2～3a、4～6a、10～14a和16a尺度的强凝聚性耦合振荡,两者年代际尺度显著相关具有阶段性而年际尺度显著相关具有时域局部化特征。气象产量与生育期降水量之间存在准2a、3～4a、8～10a和16a左右的显著共振周期,1985年以前的降水偏多期两者以负相关为主而1985年以后的降水偏少期则多为正相关关系,负相关耦合振荡的凝聚性明显大于正相关耦合振荡。华东地区水稻产量波动与区域气候变化关系密切,气候变暖对水稻产量的影响远大于降水量减少所产生的影响。气候异常导致气候灾害频发是华东地区水稻产量波动的主要原因。     

East Asian monsoon climates and Gobi dynamics in marine isotope stages 4 and 3

Several thick last glacial loess sequences in the western part of the Chinese Loess Plateau and an eolian–colluvial sequence in the central Mongolian Plateau are used to understand how the summer and winter monsoons responded to global forcing factors during marine isotope stages (MIS) 4 and 3. The magnetic susceptibility data are compared with other climatic proxy data to improve the well-publicized reconstruction of the past monsoons. This study suggests that different sensitivities between the summer and winter monsoons in responding to the northern insolation resulted in transitional climates between marine isotope stages, which were characterised by cold and wet climates in the western part of Chinese Loess Plateau. After forest–steppe in MIS 5, coniferous forest emerged at the MIS 5/MIS 4 transition in cold and moist conditions. These imply that the lower latitude oceans were still capable of supplying water vapour to the continental interior, and that the Mongolian High became dominant when the northern insolation entered a stadial state (MIS 4). Coniferous forest dominated MIS 4, but thereafter deteriorated to a steppe towards the end of the MIS 4, probably because the lower latitude oceans failed to supply water vapour to the interiors. A coniferous forest emerged again at the MIS 3/MIS 2 transition after forest–steppe in MIS 3. Consequently, the southern boundary of the Gobi Desert retreated northwards during the coniferous tree-dominated periods between 73 and 60 ka and between 27 and 19 ka, and expanded to maxima between 60 and 50 ka and between 19 and 10 ka. The extent of the Gobi Desert was considerably smaller for several times (around 47 ka and 41 ka, and 27+ ka) during MIS 3 than during the Holocene, and the northern boundary retreated 5 times (around 20 ka, 24 ka, 29 ka, 31 ka, and 34 ka) in just the later part of MIS 3.     

甘薯抗茎线虫病基因的RAPD标记

以甘薯（Ipomoea batats）高抗品种徐781和高感品种徐薯18的200个后代为实验材料，对其进行抗病性鉴定和RAPD分析，获得与抗茎线虫病基因相连锁的RAPD标记OPD01-700。经13个高抗后代、5个高感后代、8个感病后代以及已鉴定的具有稳定抗性的10个品种验证表明，该标记可作为甘薯抗茎线虫病辅助育种的分子标记。