玉米茎秆抗倒伏遗传的研究进展

茎秆倒伏严重影响玉米产量、品质和机械化收获,是当前玉米生产和育种亟待解决的主要问题之一。加强对玉米茎秆抗倒伏性的研究,对提高品种抗倒伏能力具有重要意义。本文综述了玉米茎秆倒伏的主要影响因素及其遗传特征。茎秆倒伏与茎秆自身的强度密切相关。茎秆强度越高,抗倒伏性越强。茎秆强度受茎秆所处的发育阶段、茎秆内部结构和外部形态,及其细胞壁成分等影响。处于分生组织的茎秆细胞分裂旺盛,较易折断,而进入生殖生长后,茎秆表皮、厚壁组织增厚,维管束发育成熟,对茎秆的支撑作用增强。茎秆细胞壁的主要成分——纤维素、半纤维素、木质素、可溶性糖、无机物等均可提升茎秆强度。目前,研究者借助高通量表型平台,利用玉米连锁群体和自交系群体,采用各种定位方法,鉴定到一系列影响茎秆形态、强度、细胞壁成分的相关QTL和候选基因。研究表明,基于单倍型的QTL定位方法比基于单个SNP的定位效果好。一致性QTL分析将不同遗传群体的研究整合到一起,能够提高QTL结果的通用性。茎秆强度的遗传基础复杂,受微效多基因控制,位点间具有加性效应。茎秆成分QTL中的候选基因涉及细胞壁代谢、转录因子、蛋白激酶等。MAIZEWALL是玉米细胞壁相关基因的重要数据库。目前该数据库包含1 156个玉米细胞壁生物学相关的候选基因,为该领域的深入研究提供强大的资源。已鉴定到一系列影响玉米茎秆细胞壁成分、茎秆形态和强度的基因,其功能涉及纤维素合成路径,如纤维素合成酶类、Cobra类、糖基转移酶和核糖转运蛋白类;苯丙烷路径基因,如控制bm1—bm5的相关基因;植物激素类,如赤霉素、生长素、油菜素甾醇相关基因;转录因子如NAC、MYB;miRNA（ZmmiR528）以及F-box基因（stiff1）等。今后应积极探索不同发育时期玉米茎秆倒伏的力学机制;广泛发展自然群体或育种群体进行遗传分析;采取多种定位策略,提高抗倒伏相关基因鉴定的功效;针对优良等位基因,开发各类分子标记,加强抗倒伏分子标记辅助选择。本文将为玉米茎秆抗倒伏遗传机制解析及抗倒伏玉米品种的分子育种提供参考。     

考虑水头损失的管道灌溉分水口轮灌分组优化模型

【目的】优化灌溉系统中分水口轮灌分组的灌溉制度,在满足流量要求的条件下节约电能。【方法】提出了在考虑水头损失时不同分水口状态与管道进口压力的关系模型,该模型利用分水口开关0,1状态作为自变量,从管道末端起利用推导的递推公式求出管道进水口的等效水头损失系数。依据该模型,在定流量分组轮灌优化中得到为使分组轮灌功率最小的目标函数。利用遗传算法对上述问题进行了优化求解,并给出了编码方案。【结果】在分水口等间隔布置时,轮灌分组按轮灌分组数等间隔安排所需功率最小,优化后的水头损失系数可以减小到没有优化前的0.772倍。【结论】本研究模型不仅适用于恒定流量的组合优化,也可应用于不同分水口的所需水量不同的随机灌溉以及恒压供水的优化中。     

Genetic analysis and QTL mapping of growth period traits and plant height traits in soybean recombinant inbred lines from Dongnong 47 × PI 317334-B

High and stable yield is the main goal of soybean genetic improvement. In this study, association analysis was used to detect the quantitative trait loci (QTL) for the plant height, and soybean growth period using 182 SSR markers in the RIL population of 136 F_4:8 lines, which developed from a cross between photoperiod-insensitive cultivar ‘Dongnong 47’ and photoperiod-sensitive variety PI317334–B. The results showed that 33 QTLs related to soybean growth period and plant height traits were detected by compound interval mapping, and were located on 12 linkage groups including N, C1, C2, J, D1a, B2, E, G, A2, O, L, I, with the contribution rate of 7.85–33.84%. These QTL loci and linkage markers related to soybean photoperiod sensitivity, would be helpful to identify key genes that control soybean photoperiod sensitivity, and provide an important basis for the breeding of new photoperiod-insensitive soybean varieties based on molecular design breeding.     

小麦骨干亲本临汾5064单元型区段的遗传解析

利用分子标记解析骨干亲本临汾5064单元型区段在其衍生后代中的遗传规律,可以为小麦分子育种提供依据。在临汾5064及其21个衍生品种(系)中,395个SSR标记共检测出895个等位变异,不同位点的等位变异为1~8个,平均2.27个,平均多态性指数为0.25。临汾5064及衍生后代中146个位点具有相同等位变异,遗传贡献超过80%的位点有30个。实验结果表明,临汾5064对衍生子一代和子二代的遗传贡献率分别为65.30%和64.24%,且未随着世代的增加而明显下降。所有衍生后代与亲本完全相同的单元型区段有16个,贡献率大于80%的染色体区段分布在所有染色体上。关联分析发现这些单元型区段存在重要农艺性状的QTL簇,几乎都与重要农艺性状显著相关,表明这些区段在育种过程中受到强烈选择。     

SSCP Marker Development and Analysis of Candidate Restorer Gene Rf1 for Cotton Cytoplasmic Male Sterility

[Objective] Locating the cotton cytoplasmic male sterility (CMS) restorer gene Rf₁ is important for investigating restorer gene mechanisms and improving restorer lines. In our previous study, a gene cluster, with nine Pentatricopeptide repeat(PPR) genes and nine other genes, was found within the 160-kb Rf₁ target region in Scaffold 333. The objective here was to improve the density of Rf1-linked markers in the target region and determine the expression profiles of candidate genes. [Method] Using the sequences of the 18 genes, we designed 155 single-strand conformation polymorphism (SSCP) primers covering all of the gene sequences to identify the polymorphic SSCP markers between the fertile and sterile pools. Additionally, real-time polymerase chain reaction(PCR) was performed to analyze the expression profiles of eight candidate genes in the four developmental stages of buds of sterile, maintainer and restoring lines, respectively. [Result] In total, 15 polymorphic primers were identified. A genotype analysis of the F₂ population was conducted using the 15 primers and 3 other polymorphic simple sequence repeats (SSR) markers. The markers were distributed in a 4.8 cM range. In addition, owing to the influence of sterile cytoplasm or restorer genes, most of the genes showed different expression patterns in the four developmental stages of the three lines' buds. [Conclusion] SSCP markers tightly linked to Rf₁ were identified and the expression profiles of candidate genes were determined. This study provides a basis for the further fine mapping of restorer genes and for candidate gene screening.     

Genetically engineering better fungal biopesticides

Microbial insect pathogens offer an alternative means of pest control with the potential to wean us off our heavy reliance on chemical pesticides. Insect pathogenic fungi play an important natural role in controlling disease vectors and agricultural pests. Most commercial products employ Ascomycetes in the genera Metarhizium and Beauveria. However, their utilization has been limited by inconsistent field results as a consequence of sensitivity to abiotic stresses and naturally low virulence. Other naturally occurring biocontrol agents also face these hurdles to successful application, but the availability of complete genomes and recombinant DNA technologies have facilitated design of multiple fungal pathogens with enhanced virulence and stress resistance. Many natural and synthetic genes have been inserted into entomopathogen genomes. Some of the biggest gains in virulence have been obtained using genes encoding neurotoxic peptides, peptides that manipulate host physiology and proteases and chitinases that degrade the insect cuticle. Prokaryotes, particularly extremophiles, are useful sources of genes for improving entomopathogen resistance to ultraviolet (UV) radiation. These biological insecticides are environmentally friendly and cost‐effective insect pest control options. © 2017 Society of Chemical Industry     

中国榛属植物资源培育与利用研究(Ⅰ)——榛种质资源研究

原产中国的榛属植物有8个种和2个变种,约占全世界种数的一半。榛子是传统的木本粮油树种,中国先民自古以来就采集野生榛子食用。中国榛属植物种质资源分布经纬跨度较大(24°31'~51°42'N、85°55'~132°12'E),从"东北—华北山区、秦岭和甘肃南部及河南—华中—云贵高原"呈斜带状,海拔从100~4 000 m都有分布,行政地域范围涉及25个省(自治区、直辖市)。通过地理分布生态适应性研究,建立了榛属植物分布种数与气候因子间的回归方程:Y=11.883-0.051X_1+0.131X_2-0.003X_4-0.004X_5-0.001X_6+0.051X_8。初步提出了榛属植物资源描述与评价体系,开展了榛坚果、花粉形态及雄花序等形态多样性研究,并且在分子水平上对榛属植物遗传多样性和系统进化进行了研究,明确了川榛应该作为一个独立的种,平榛与欧洲榛尽管地理位置较远,但是遗传距离较近,这既说明了平榛和欧洲榛杂交成功的原因,同时也为进一步研究榛树植物地理距离和遗传距离的不一致性提出了新的课题。     

基于距离相关系数和KNN回归模型的森林蓄积量估测研究

【目的】探究Landsat8 OLI数据和KNN算法在森林蓄积量估测中的潜力。【方法】以湖南省湘潭县为研究区,采用Landsat8 OLI数据和同时期的二类调查数据,通过距离相关系数筛选特征,分别采用线性回归模型(MLR)、K-近邻模型(KNN)、距离加权KNN模型(DW-KNN)和优化欧式KNN模型(FW-KNN)对森林蓄积量进行估测。使用十折交叉方法进行精度检验,对检验结果进行对比分析。【结果】3种KNN模型的估测结果均高于传统的线性模型,并且在3种KNN模型中,FW-KNN算法效果最好,决定系数达到0.69,为3种模型中最高;3种KNN模型中,本研究优化欧氏距离KNN模型的估测精度最高,其均方根误差为30.3%,相比于传统KNN模型的均方根误差降低了5.1%,相比于DW-KNN模型降低了3.3%。【结论】采用DW-KNN蓄积量估测结果明显优于其他两种模型,说明通过特征与蓄积量的相关性优化样本间的距离是一种可行的KNN优化方法。