Resistance gene analogue isolation and RGA-based marker development for identifying downy mildew resistance in radish (Raphanus sativus L.)

Resistance Gene Analogs (RGAs)-based molecular markers can significantly enhance the breeding efficiency for disease resistance in various crops. However, RGAs isolation and RGA-based marker development have not been conducted in radish. In this study, two prevalent approaches, PCR amplification with degenerate primers and data-mining of radish EST databases, were used to isolate radish resistance gene candidate sequences. A total of 26 RsRGAs with high homology to known R-genes or RGAs were obtained by PCR amplification. Meanwhile, 257 R-gene-like unigenes/ESTs were identified using data-mining method. In total, 115 out of 124 designed RGA-specific primer pairs can successfully amplified the target bands. To explore the RGA genetic variability, 32 radish accessions were genotyped and 269 RGA loci were successfully identified. It was found that 44 RGA primers only generated monomorphic band and the remaining 71 RGA primers generated 225 RGA polymorphic bands among the 32 radish accessions. Based on RGA marker analysis, 32 radish accessions were clustered into four main groups at the similarity index of 0.68, which was in a high accordance with disease index from a downy mildew evaluation. This study might be the first report on candidate R-genes identification and RGA-based markers development in radish. These findings will facilitate the disease resistance identification and speed up the genetic improvement of DM resistances in radish breeding programs.     

Standardized methods for the determination of antioxidant capacity and phenolics in foods and dietary supplements

Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin-Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin-Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology.     

石灰岩与白云岩坡地土壤饱和导水率对比研究

[目的]对比研究不同下垫面特征和土地利用方式对两类坡地表层土壤性质及其土壤饱和导水率(Ks)的影响。[方法]以喀斯特地区不同岩性下垫面的石灰岩和白云岩两类坡地表层土壤为研究对象,采用Guleph稳定入渗仪和土壤分析的方法。[结果](1)石灰岩和白云岩表层土壤在受到放牧作用影响后,土壤均呈现显著退化趋势,其容重、黏粒含量增大,孔隙度、有机质含量降低。(2)石灰岩和白云岩两类坡地表层土壤在未受到人为干扰的自然植被条件下,由于表层岩溶带的发育,Ks都很高,平均值分别为328.6和257.2mm/h。其中,石灰岩坡地相比白云岩坡地,Ks具有更高的空间变异性,二者Ks变异系数变化范围分别为90.71%~95.62%和59.60%~67.32%。(3)受到放牧作用影响后,石灰岩和白云岩坡地表层土壤Ks相比自然植被状态下呈显著降低趋势,Ks分别降低52.2%和86.7%,白云岩坡地Ks降低程度大,高于石灰岩坡地。     

CERN分布式土壤样品长期保存系统的构建

长期保存的土壤样品是国家科技基础支撑条件的重要组成部分,对于土壤及环境长期变化研究和科学数据开放共享等具有重要价值。近年来,随着我国对农业和生态环境科技投入的不断增长,土壤调查强度逐步增大,土壤样品积累速度明显加快,因此,亟需相关的标准规范来指导土壤样品的长期保存。在国家标准《土壤质量 土壤样品长期和短期保存指南》（GB/T32722-2016）的基础上,结合“十三五”期间CERN分布式土壤样品长期保存系统建设经验,本文对土壤样品保存管理策略、土壤样品保存条件要求和土壤样品信息管理系统进行了介绍,以期为我国土壤样品长期标准化保存,以及第三次全国土壤普查样品库建设提供参考。     

外源钙对果实发育过程中肥城桃钙素动态变化的影响

为探究肥城桃各器官钙素分配及动态变化规律,本研究以11年生肥城桃为试验材料,采用树干注射⁴¹Ca同位素及外施钙肥(0.5%氨基酸钙和0.5%硝酸钙溶液,清水为对照)处理,检测各器官⁴¹Ca丰度变化及总钙含量。结果表明,在生长前期,新梢、叶片钙含量增加均最为明显,分别增加40%~68%、13%~28%;果实中的钙含量在幼果期达到最大值,随后逐渐降低;多年生枝的钙含量呈先下降后上升的趋势;叶片对树体中⁴¹Ca的竞争能力远超过果实等组织;成熟期⁴¹Ca分配情况为树干最高,占67.78%,叶片、枝条次之,果皮、果肉再次,树干皮及枝条皮最低。综上,在肥城桃果实发育各时期喷施不同形态钙肥能有效提高果实、新梢、叶片等幼嫩器官的钙含量,利用⁴¹Ca示踪-加速器质谱技术可较准确的研究钙素在植物体内的运动分布规律。本研究结果为肥城桃科学补钙提供了理论依据。     

温度条件对辽宁南部玉米生长发育和产量的影响——以庄河分期播种试验为例

利用2012年庄河5期分期播种试验资料,分析温度条件对辽宁南部春玉米生长发育及产量的影响.结果表明:在光照和水分条件适宜情况下,玉米各生育期持续时间受温度条件影响较为明显,出苗、苗期及灌浆期随温度升高而缩短,其中出苗时间对日最低气温比日均温响应更为明显.玉米生长状态在营养生长阶段受温度影响较小,而产量形成过程因不同温度条件对干物质积累影响的差异而不同.产量形成不但取决于灌浆期积温,同时还受气温日较差和日最低气温的影响.对于庄河地区而言,适当晚播将有利于玉米各生育期经历更为适宜的温度条件进而提高产量.     

林口林区重点公益林经营抚育的探讨

根据国家林业局重点公益林中幼龄林抚育项目,林口林业局在重点公益林区开展了试验示范,并设置样地进行了观测调查,取得了相关数据,为国家重点公益林的经营培育提供了科学的理论依据。     

Configuration dynamics of boreal forest landscapes under recent fire and harvesting regimes in western Canada

Harvesting and forest fire change the spatial configurations of forest habitat. We used multivariate statistical models to evaluate the individual and cumulative effects of these two disturbances on habitat configuration in managed boreal forest landscapes in western Canada. We evaluated three aspects of configuration (core area, inter-patch distance and shape) using indices normalized for total habitat abundance. The two disturbances types had different effects on the three configuration metrics in terms of both the magnitude and direction of change. We found that the magnitudes of harvesting effects were larger than for fire. The direction of change was the same for core area and shape, but opposite for inter-patch distance which decreased slightly after fire. The combined effects of the two disturbances are distinct from the effects of either disturbance alone, and the effects are not always additive or compensatory for all metrics. Pre-treatment configuration was a significant covariate in all models, and total habitat abundance was significant in 4/9 models, but these were often not the most important covariates. In the cumulative disturbance model, covariates for the number or size of cut-blocks were significant.     

藏茴香总DNA提取方法探究

本试验取藏茴香叶片制成干样、鲜样,采用SDS法、CTAB法、改良SDS法、改良CTAB法、试剂盒法五种提取方法对其总DNA进行提取,比较DNA样品的纯度、得率、完整度等指标,以期获得优质高效的藏茴香总DNA的提取方法。试验结果如下:材料选用藏茴香叶片干样所提取的总DNA效果好。用试剂盒法和改良CTAB法提取的藏茴香总DNA样品质量优良、完整性好、纯度高,明显优于其他方法;使用改良CTAB法和试剂盒法所提取的藏茴香DNA进行PCR检测,获得了明亮清晰的扩增图谱;从成本方面考察,试剂盒法远高于其他方法。因此,改良CTAB法提取藏茴香干样总DNA效果最佳。     

植物化感作用研究进展

本文从植物化感物质的种类、释放途径、作用机理及化感物质的自毒作用等角度论述了植物化感作用的原理,指出自毒作用是连作障碍的主要因子,进而提出减弱或消除自毒作用的技术措施和途径。