北京城乡居民收入差距的结构性分析

为研究北京市城乡居民收入差距状况,对北京及全国城乡统筹发展提供依据。应用时间序列数据,对1990-2009年北京市城乡居民收入差距的演变进行分析,并运用基尼系数法,对北京市城乡居民收入差距进行了组间结构分析和分项结构分析。结果表明：1990-2009年间,北京城乡居民收入差距不断扩大,农村居民内部收入差距较显著,工资性收入和转移性收入对城乡居民收入差距影响较大。     

冬小麦低温处理叶片细胞膜透性的QTL定位

为探索冬小麦抗寒性的分子机制,以168个花培3号×豫麦57的双单倍体株系为作图群体,利用已构建含有324个SSR标记的遗传图谱,对电导法测定低温(−18℃)处理后的叶片膜透性进行QTL定位。利用完全区间作图法,在3种环境下共检测到21个与叶片膜透性相关的加性QTLs,分布于1B、2A、3A、3B、5B、6A、6B、6D、7B和7D染色体上,其中4个位点(qCMP-1B-1、qCMP-3B-2、qCMP-5B-1和qCMP-5B-4)遗传贡献率大于10%,属主效基因,其余QTL的遗传贡献率较小,属微效基因。3种环境条件下在5B染色体的Xgwm213–Xswes861.2区间检测到共同位点,与Xswes861.2的遗传距离为0 cM,其中qCMP-5B-1 (环境1)和qCMP-5B-4 (环境3)的贡献率高达17.5%和14.0%。研究结果对于小麦抗寒标记选择和抗寒育种具有应用价值。     

大叶伞干腐病病原菌的鉴定及杀菌剂毒力测定

为明确大叶伞干腐病的病原菌种类,筛选有效药剂,为病害防治提供理论依据,对该病病原菌进行了鉴定,并进行了杀菌剂毒力测定。在形态学基础上,结合rDNA-ITS序列分析,对大叶伞(Schefflera actinophylla)干腐病病原菌进行鉴定,结果为可可毛色二孢菌(Lasiodiplodia theobromae)。采用菌丝生长速率法,测定了8种杀菌剂对大叶伞干腐病菌的抑制作用,结果表明：50%多菌灵可湿性粉剂抑菌效果最好,EC50为0.02 μg/mL,其次为45%咪酰胺水乳剂、43%戊唑醇悬浮剂和10%苯醚甲环唑水分散性粒剂和25%丙环唑乳油,EC50值均小于1 μg/mL。     

QTL analysis of seed dormancy in rice (Oryza sativa L.)

Effective cumulative temperature (ECT) after heading would be a more reasonable parameter for seed sampling of pre-harvest sprouting/seed dormancy (SD) tests in segregating populations than the days after flowering. SD is an important agronomic trait associated with grain yielding, eating quality and seed quality. To identify genomic regions affecting SD at different grain-filling temperatures, and to further examine the association between SD and ECT during grain-filling, 127 double haploid (DH) lines derived from a cross between ZYQ8 (indica)/JX17 (japonica) by anther culture were analyzed. The quantitative trait loci (QTLs) and their digenic epistasis for SD were identified using a molecular linkage map of this population. A total of four putative QTLs for SD (qSD-3, qSD-5, 6 and 11) were detected on chromosomes 3, 5, 6 and 11, together explaining 41.4% of the phenotypic variation. Nine pairs of digenic epistatic loci were associated with SD on all but chromosome 9, and their contributions to phenotypic variation varied from 2.87%–8.73%. The SD QTL on chromosome 3 was identical to the QTLs found in other mapping populations with different genetic backgrounds, which could be a desirable candidate for gene cloning and marker-assisted selection in rice breeding.     

Genetic analysis of methionine content in indica-japonica hybrid rice (Oryza sativa L.) at different grain developmental stages

Genetics of methionine content in indica-japonica hybrid rice (Oryza sativa L.) was studied in 35 F₁ hybrids derived from crossing 7 male-sterile indica rice cultivars with 5 restorer japonica rice cultivars. Two genetic models and their corresponding statistical methods for quantitative traits of triploid endosperm in cereal crops were used for the analysis. One is the unconditional model, which refers to the analysis of cumulative measurements along the developmental stages, while another is the conditional model, which relates to analysis throughout the developmental stages. Results showed that methionine content of indica-japonica hybrid rice was controlled by expression of triploid endosperm nuclear genes, cytoplasm genes, diploid maternal plant nuclear genes, and their genotype-environment interaction effects. Dominant effects were important at the first three developmental stages, while additive effects were important at the next two stages of grain development under both unconditional and conditional analyses. With regard to the components of heritability, maternal and cytoplasm general heritabilities and their environmental interaction heritabilities were important. It was suggested that enhancing methionine content could be more efficient when selection is based on maternal plants in early breeding generations.     

CRISPER/Cas9系统在植物基因组定点修饰及作物遗传育种中的应用研究进展

CRISPR/Cas9系统是一项简单、高效的基因定点编辑技术,在植物遗传改良及作物良种选育等方面具有重要的应用价值。本研究主要介绍了CRISPR/Cas9的原理及构建方法,论述了近年来CRISPR/Cas9技术在植物基因功能及基因表达调控、植物基因组的定向编辑以及作物分子育种中的应用及研究进展,分析了该基因编辑系统的主要影响因素及优化改进方式,探讨了该系统在应用中的问题及解决途径并对今后发展方向进行了展望,为该技术在植物基因组定点编辑及作物遗传育种等领域研究提供参考。     

玉米籽粒主要品质性状的分子遗传研究进展

玉米是全球最主要的粮食作物之一,提高玉米籽粒品质是当今世界玉米育种领域高度关注的问题。因为传统常规育种方法具有育种时间长且转化率低等限制因素,所以解决这一问题最经济有效的方法就是利用分子标记进行辅助选择育种。为了给今后玉米品质性状的分子设计育种提供参考,本研究总结了国内外玉米籽粒品质性状的QTL定位、分子标记辅助改良和候选基因克隆及转基因技术应用的相关研究进展。指出玉米优质基因资源的利用还不够充分,现有分子标记技术在玉米育种中的应用还不够广泛,今后应改进育种方法和品质鉴定技术,以缩短玉米育种周期。     

梨属植物等位酶遗传多样性研究

利用超薄平板微型聚丙烯酰胺凝胶的等电聚焦电泳技术,对286份梨材料进行了等位酶遗传变异分析。在8个酶系中共检测到19个清晰位点和82个等位基因,19个位点均为多态位点,位点最大等位基因数为6,体现出梨丰富的遗传种质多样性;不同的居群具有特有等位基因;通过82个等位基因可以将286份材料完全区分开,表明等位酶基因型指纹可用作梨品种区分与鉴定的依据。     

利用“永久F2”群体定位抗赤霉病QTL

为了研究抗赤霉病侵染性的遗传, 利用感赤霉病品种南大2419和抗赤霉病品种望水白杂交单粒传获得的重组自交系群体132个株系间的随机配对组合, 构建了一个包含198个株系的“永久F2”群体。通过两年抗侵染田间试验和QTL作图, 定位了6个抗侵染QTL, 其中抗性等位位点源于望水白的Qfhi.nau-4B和Qfhi.nau-5A以及源于南大2419的Qfhi.nau-2B的效应较为稳定。Qfhi.nau-4B和Qfhi.nau-5A的效应较大且以加性效应为主, 前者存在部分显性基因效应。此外, 还检测到4对显著的互作位点。这些结果进一步说明赤霉病抗性遗传的复杂性, 同时也表明在利用望水白进行抗赤霉病育种时早代选择抗侵染性是可行的。     

不同栽培模式与密度对小豆花后干物质积累及产量的影响

为探明栽培模式与群体密度对小豆植株干物质积累及产量的影响,采用平作和65 cm宽垄作2种栽培模式,分别采取9万、13万、17万、21万、25万株/hm~2群体密度,测定小豆花后不同部位器官的干重,并于成熟收获后取样测定产量构成。结果表明:随着群体密度的增加,小豆的单株结荚数量和粒数显著降低,单株产量的降低,导致平作条件下随着群体密度的增加产量无显著变化;而垄作条件下,小豆植株的营养器官干重高峰期出现较晚,在鼓粒阶段营养器官仍保持较大干物质积累,单株的结荚数和粒数增加了3.8%~53.8%和13.6%~101.5%,因此,在相同密度条件下垄作的单株产量和单位面积产量显著高于平作17.3%~127.2%和36.8%~80.0%。综合分析小豆的植株形态和产量构成,采用垄作条件保苗株数17万株/hm~2更利于小豆产量的形成,而平作条件下种植密度不易超过21万株/hm~2。