Regional and temporal differentiation of virulence phenotypes of Puccinia triticina from common wheat in Russia during the period 2001–2018

Leaf rust, caused by the fungus Puccinia triticina, is one of the most damaging rust diseases of wheat in Russia. Populations of P. triticina were monitored in seven regions of Russia from 2001 to 2018, with a total of 5,191 single urediniospore isolates from bread wheat (Triticum aestivum) being analysed. Populations have changed significantly in all regions since 2012, after 2 years of drought (2010–2011). Regional collections of P. triticina were also significantly different between the two periods 2001–2009 and 2012–2018, with changes along two geographic gradients from West Siberia to the north-west and south-west (North Caucasia) of the European part of Russia. All tested isolates were avirulent to resistance gene Lr9 in 2001–2009 but, since 2010, virulence to Lr9 has occurred and annually increased in the Asian part of Russia (Ural and West Siberia) due to deployment of cultivars with the Lr9 gene. Virulence to Lr2a and Lr15 was considerably lower in Dagestan (6%–33%) and all European regions (35%–67%) than in Asian regions (84%–96%). During 2001–2009, virulence on Lr1 was also lower in Dagestan (33%) and the European regions (50%–77%) than in Asia (91%–96%); however, by 2012–2018, nearly all isolates were virulent on Lr1. Remarkable changes were observed in frequencies of P. triticina races defined by their virulence/avirulence to Lr1 and Lr2a genes. We postulate the P. triticina population in Dagestan is specific to that area and pathogen populations in European and Asian parts of Russia are distinct.     

混合盐胁迫对马蔺幼苗根系构型及生长量的影响

为探讨不同种类盐胁迫对马蔺幼苗生长状况的影响,采用室内培养的方法,研究总质量浓度为0.3%的NaCl、NaHCO₃单盐溶液及其不同配比的混合盐溶液胁迫对马蔺(Iris lactea var. chinensis)幼苗生长量、地上部干鲜重比值、地下部干鲜重比值以及根系构型的影响。结果表明,随着胁迫时间的延长,0.3%NaCl溶液对叶数和株高增长量的影响最小,其次为3种混合盐溶液,各处理在第14天时株高增幅达到最大。经0.3%NaHCO₃处理后的幼苗地上部干鲜重的比值为空白对照的2.17倍,地下部干鲜重则为空白对照的56.61%,随着混合溶液中NaHCO₃浓度的上升,地上部干鲜重比值表现出上升的趋势,地下部干鲜重比值则表现出下降的趋势。经35天处理后,0.3%NaHCO₃胁迫的马蔺幼苗根系总长、根系表面积较对照均显著下降,降幅分别为39.73%、26.08%,而各处理间的根系体积却无显著差异。研究结果显示,0.3%NaHCO₃溶液对马蔺幼苗的胁迫作用最强,2种单盐对根系的胁迫作用强于混合盐胁迫,而0.3%NaCl溶液对生长量的胁迫作用最弱。     

Influence of intra-row cruciferous surrogate weed growth on crop yield in organic spring cereals

In Northern Europe, inter-row hoeing has become a popular tactic for controlling weeds in organic cereals. Hoeing is highly effective and can be implemented from crop emergence until stem elongation to maintain a nearly weed-free inter-row zone. However, hoeing has a lesser effect on weeds growing in the intra-row zone, where crop–weed proximity results in heightened competition. In the hoed cereal system, it is investigated whether tall-growing, competitive, cruciferous weeds in the intra-row zone affect crop biomass, yield and thousand kernel weight (TKW). An additive experimental design is employed to enable the fitting of rectangular hyperbolas, describing and quantifying the effects of increasing intra-row surrogate weed density on crop growth parameters. Regressions were studied under the influence of crop (spring barley and spring wheat), row spacing (narrow [12.5 or 15.0 cm] and wide [25.0 cm]) and nitrogen rate (50 and 100 kg NH₄-N/ha). Cruciferous surrogate weeds were found to impact crop yield and quality severely. For example, ten intra-row plants/m² of surrogate weed Sinapis alba reduced grains yields by 7%–14% in spring barley and by 7%–32% in spring wheat with yield losses becoming markedly greater in wheat compared to barley as weed density increases. Compared to wheat, barley limited yield and quality losses and suppressed intra-row weed growth more. Row spacing did not have a consistent effect on crop or weed parameters; in one of six experiments, the 25 cm row spacing reduced yields and increased intra-row weed biomass in wheat. Nitrogen rate did not affect crop or weed parameters. Results warrant the implementation of additional tactics to control intra-row weeds and limit crop losses.     

Tree-ring response of Larix chinensis on regional climate and sea-surface temperature variations in alpine timberline in the Qinling Mountains

Tree-ring width chronologies of Larix chinensis were developed from the northern and southern slopes of the Qinling Mountains in Shaanxi Province,and climatic factors affecting the tree-ring widths of L.chinensis were examined.Correlation analysis showed that similar correlations between tree-ring width chronologies and climatic factors demonstrated that radial growth responded to climate change on both slopes.The radial growth of L.chinensis was mainly limited by temperature,especially the growing season.In contrast,both chronologies were negatively correlated with precipitation in May of the previous year and April of the current year.Spatial climate-correlation analyses with gridded land-surface climate data revealed that our tree-ring width chronologies contained a strong regional temperature signal over much of northcentral and eastern China.Spatial correlation with seasurface temperature fields highlights the influence of the Pacific Ocean,Indian Ocean,and North Atlantic Ocean.Wavelet coherence analysis indicated the existence of some decadal and interannual cycles in the two tree-ring width chronologies.This may suggest the influences of El Nin˜o-Southern Oscillation and solar activity on tree growth in the Qinling Mountains.These findings will help us understand the growth response of L.chinensis to climate change in the Qinling region,and they provide critical information for future climate reconstructions based on this species in semi-humid regions.     

旱垂柳转录组测序及赤霉素在垂枝形成中的作用

垂枝作为特殊的林木形态结构,因形态优美在全世界被广泛用于绿化和园林景观而成为研究热点。国内外对垂枝植物的研究表明赤霉素在垂枝形成中起作用,但是垂枝形成的分子背景研究仍比较缺乏。本研究以旱垂柳(Salix matsudana var. pseudo-matsudana)的垂枝为研究对象,通过对旱垂柳在不同生长发育时期的叶片、茎尖和茎基部进行了转录组和数字表达谱测序研究,共获得71 474个Unigenes序列。将Unigenes与COG和KEEG数据库比对,与转录和信号转导机制相关的基因在旱垂柳中高度富集,最终确定8 359个差异表达的基因,其中427个基因与激素相关。进一步分析赤霉素相关基因得出,主要参与2条赤霉素合成途径,具有生物活性的GA4是合成途径中的主要产物,而且GA4在枝条中的含量显著高于GA1和GA3。参与赤霉素信号转导途径中的GID1B在旱垂柳中上调表达,以及在G1和G4生长期的表达量高于其他时期,而DELLA蛋白GAI在G2生长期以后下调表达,GID1B和GAI在旱垂柳的垂枝生长过程中可能起非常重要的作用。这些研究结果将有助于探索赤霉素在旱垂柳垂枝形成中的分子作用,可为林木形态的遗传改良提供基础理论依据。     

直立型扁蓿豆对干旱胁迫和复水的响应及适应策略

以直立型扁蓿豆[Medicago ruthenica（L.）Sojak.cv.Zhilixing]为材料，于苗期连续干旱处理12 d后复水4 d，研究直立型扁蓿豆幼苗形态结构特征、生理代谢及生物量分配对干旱胁迫及复水的响应，揭示直立型扁蓿豆对干旱胁迫及复水的适应策略。结果表明：随着干旱胁迫时间延长，直立型扁蓿豆叶片气孔开放率逐渐降低，处理9 d后气孔及表皮细胞密度比正常浇水处理（CK）分别增加48.5%和36.6%，形成小而密的表皮细胞和气孔。生理上，除MDA含量随胁迫时间的延长逐渐增加外，其余指标均先升高后降低，干旱胁迫9 d时达最高，SOD、POD、叶绿素、可溶性糖、可溶性蛋白及脯氨酸分别较CK提高88.9%、111.2%、86.7%、140.5%、147.8%和124.6%。同时，生物量随胁迫时间的延长先增大后减小，于干旱胁迫9 d达最大值，比CK增加16.4%，总的分配格局表现出地上生物量投资高于地下，地下生物量投资比例随胁迫时间的延长逐渐增加，而地上生物量变化与其相反。复水后各指标均能恢复至CK水平或超过CK，表现出极强的复水敏感性和潜在恢复能力。该品种扁蓿豆对干旱胁迫及复水的适应主要分为3个时期：主动适应期，其生理参数的可塑性指数为形态参数的1.33倍，主要通过抗氧化及渗透调节来减少水分散失增加水分吸收、缓解氧化伤害以适应干旱逆境；被动适应期，其形态参数的可塑性指数为生理参数的1.31倍，主要采用牺牲生物量的生存策略以及降低色素含量减少光吸收的光保护机制来提高逆境下的生存能力；复水恢复期，根冠比、气孔开放率、气孔及表皮细胞密度比CK分别增加25.9%、29.7%、24.2%和16.3%，其较高的根冠比和叶片较高的气孔开放率及小而密的气孔及表皮细胞特征，保证了直立型扁蓿豆吸水能力以及水分运输效率的迅速恢复。综上，直立型扁蓿豆抗旱能力较强，能够通过形态生理的改变以及调整不同器官的生物量分配来应对与适应干旱逆境及复水，且在不同处理阶段采取不同的适应策略以达到生存目的。     

Effects of oral administration of Spirulina platensis and probiotics on serum immunity indexes,colonic immune factors,fecal odor,and fecal flora in mice

To evaluate the effects of Spirulina platensis and probiotics on growth, immunity indexes, fecal flora, and fecal odor in mice, 40 mice were randomly allotted to four groups, and each was administrated with nothing, S. platensis, probiotics, or both for 28 days, respectively. Then, many indexes were measured. The results showed that S. platensis was more effective (P < 0.001) than probiotics in improving mice's feed conversion ration (FCR). In immunity, probiotics administration increased (P < 0.042) serum IgE, IgM, IFN-γ, colonic AHR, TLR4, and NF-κB protein expression and decreased (P < 0.039) serum IL-1α, IL-21, IL-22, and colonic ARNT gene expression. However, the S. platensis showed weaker effect, which increased (P < 0.025) the serum IgE, IgM, TNF-α, and the colonic AHR and NF-κB protein expression, and decreased (P < 0.01) serum IL-21. Probiotics consumption decreased the fecal odor by decreasing (P < 0.02) fecal Escherichia coli, indole-3-acetic acid (IAA), and skatole contents, and the S. platensis decreased (P = 0.04) the IAA. These results indicated that oral administration of probiotics, S. platensis, or both of them in mice probably benefited body's immunity and reduced fecal odor. However, their mechanisms were still unclear and need further study.     

天山云杉林冠层结构对草本物种多样性的影响

为研究天山云杉林冠层特征与林下草本物种多样性的相互关系，以新疆天格尔森林公园天山云杉林的4个龄级的林分（幼林龄、中林龄、近熟林、成熟林）为研究对象，以冠层分析仪获得的冠层结构特征和林下光环境指数等野外实际调查数据为依据，通过计算 α 多样性指数分析4个龄级的草本物种多样性，利用多元统计方法研究冠层结构对草本多样性的影响。结果表明，各个指标在不同龄级间均有一定的差异，且随着林分的生长和更新，天山云杉林呈现林冠开度逐渐减小、叶面积指数增大、林下光辐射均减弱、物种多样性指数均减小的趋势；典型模型表明林冠开度对冠层结构起到主要作用（呈极显著正相关P<0.01），叶面积指数次之（呈极显著负相关P<0.01）；在林下辐射中，林下总辐射对林内光环境起主要作用；相比冠层结构，林下光照对草本层物种多样性的作用更大，其中林冠开度和丰富度指数之间呈显著正相关，林下总辐射、林下直射辐射和多样性指数、均匀度指数之间均呈显著正相关。     

蔬菜农药残留检测中基质效应影响因素分析

为了提高农药检测的准确率,试验选择气相色谱(7890A、1310)与气相串联质谱(GCMS-MS)3种不同仪器,结球白菜、结球甘蓝、黄瓜、辣椒4种蔬菜样品及其基质标准溶液和正己烷溶剂标准溶液,对4种不同蔬菜中分别添加腐霉利、甲氰菊酯、氯氰菊酯、溴氰菊酯4种农药并进行回收校正,比较不同的校正溶液、不同仪器以及不同的样品类型对蔬菜农药残留检测中的基质效应的影响。结果显示:按不同基质标准溶液和溶剂标准溶液校正的检测结果分类,不同蔬菜、不同的标准校正溶液对于农药残留检测中的基质效应表现出多样性和复杂性的特点。但采用与本底一致的基质标准溶液校正样品可有效消除基质效应。按不同仪器检测结果分类,气相色谱(7890A、1310)与气相串联质谱(GC-MS-MS)基质效应的影响存在一定的差异,GC-MS-MS存在较为明显的基质增强效应;而同类仪器(7890A、1310)之间基质效应的影响较小。     

国家地理标志保护产品——北乡马蹄

为了提高北乡马蹄的产量和质量，使北乡马蹄创造出更大的经济价值，为当地的农户创造更高的收益，通过了解当地的情况，阐述了北乡马蹄的基本特征及种植现状；结合现代农业技术，总结出北乡马蹄高效栽培技术要点，包括种球选择、育秧、定植、田间管理、病虫害防治及采收等。