利用分子标记分析高粱的遗传多样性及其在种质创新中的应用

分子标记由于能够反映DNA水平上的遗传变异而成为研究遗传多样性的重要方法。本文综述了利用分子标记分析高粱遗传多样性的研究进展,并阐述了遗传多样性分析在种质创新中的应用方向,提出了利用分子标记分析高粱遗传多样性研究中尚需进一步加强的研究内容。     

高粱遗传转化研究进展

高粱是世界上仅次于小麦、水稻、玉米和大豆的重要作物之一,然而由于其高效、稳定的遗传转化体系的建立较难,限制了其转基因研究进程.近年来,随着转基因技术的不断发展和完善,高粱转基因研究也取得了飞速的发展.从高粱遗传转化再生系统中外植体的选择、转化方法、影响转化和基因表达效率的因素等几方面进行了综述,并总结转基因高粱研究进展.     

高粱基因组学研究的新进展

高粱是全球第五大禾谷类作物,在干旱、半干旱地区农业生产中占有极其重要的位置.高粱基因组相对较小(750Mbp),遗传多样性丰富,被认为是禾谷类作物比较基因组学研究的模式基因组之一.近年来,综合运用AFLP等分子标记、BAC文库、EST及cDNA作图和FISH技术,加速了高粱高分辨率基因组图谱的构建.高粱基因测序、基因功能鉴定和克隆,以及遗传转化,亦取得了长足的进展.高粱特有的多种适应逆境胁迫等优异基因资源的发掘及其在作物改良中的应用前景广阔.     

高粱品种BTx623原生质体分离及瞬时表达体系的建立

高粱(Sorghum bicolor)是世界上仅次于小麦、水稻、玉米和大麦的重要粮食作物之一,虽然高粱基因组已经完成了测序,但是针对高粱测序品种BTx623,遗传转化方法的缺乏限制了高粱遗传育种和功能基因组研究的发展。而原生质体瞬时表达技术,则因为其高效、快速的特性,在功能基因组研究中具有重要的作用。为了在高粱品种BTx623中建立原生质体瞬时表达体系,本研究以BTx623幼苗为材料,对原生质体分离过程中的渗透压、酶液成分、酶解时间进行研究。结果表明:BTx623幼苗的原生质体分离过程中,最佳酶解液组成为1%纤维素酶、0. 25%离析酶、0. 6 mol/L甘露醇、10 mmol/L吗啉乙烷磺酸、1mmol/L CaCl_2、0. 1%小牛血清蛋白和5 mmol/Lβ-巯基乙醇,并获得了每毫升1×107个的高质量原生质体,所获原生质体活性在90%以上。之后利用PEG介导的转化方法,将含有35S::egfp的质粒导入到原生质体中,并通过荧光显微观察统计,遗传转化率达到(61. 31±3. 91)%。本研究通过优化高粱品种BTx623原生质体制备及瞬时转化的条件,成功建立了其原生质体瞬时表达体系,为进一步开展高粱品种BTx623功能基因组的研究奠定了基础。     

高粱抗旱性鉴定方法及相关QTL定位研究进展

高粱[Sorghum bicolor(L.)Moench]是世界上重要的粮食、饲料、纤维和能源作物之一,因其根系发达、叶片蜡质层厚密、渗透调节能力强、光合效率高等特点,在干旱条件下具有很强的适应性。因此,高粱在气候变化、水资源短缺和满足世界粮食需求等方面发挥着重要的作用。干旱是制约世界农业生产的主要逆境因素之一,如何解决高粱在干旱条件下的产量问题仍然是育种工作者面临的巨大挑战。为了给高粱抗旱育种提供参考,本文综述了高粱抗旱性的鉴定方法、鉴定指标和优异抗旱种质资源,以及高粱花前抗旱和花后抗旱相关性状QTL定位的研究进展,并对高粱抗旱性研究的发展趋势提出了展望。认为应建立规模化高粱种质资源抗旱鉴定体系、选择合适的全生育期自然鉴定地点,筛选抗旱种质资源;利用高通量测序技术,高效挖掘高粱抗旱性基因;建立高粱遗传转化体系、运用基因编辑等生物技术,加快高粱抗旱育种进程。     

作物基因聚合分子育种

基因聚合分子育种与常规育种技术相结合已成为今后作物育种的主流方向。基因聚合分子育种主要包括遗传转化基因聚合分子育种和分子标记筛选基因聚合分子育种。本文简要综述了近年来作物基因聚合分子育种的研究进展,分析了遗传转化基因聚合分子育种以及分子标记基因聚合分子育种技术的研究方法及基因聚合分子育种存在的问题。     

高粱组织培养技术研究进展

高粱是全球第五大谷类作物,是食品、饲料和加工业的原料,也是一种潜在的能源作物,具有重要的应用价值。然而,通过基因工程技术对高粱进行遗传改良却十分困难,其主要原因是缺乏高效的组织培养体系。结合近年来的研究,从基因型、外植体、培养基、植物激素等影响高粱组织培养的主要因素进行综述,重点讨论了促进高粱再生的策略,并提出解决高粱组培再生困难的两大研究方向:一是深入研究植物再生的遗传及表观遗传机制;二是根据各基因型的代谢特点,进一步优化培养条件,旨为建立高效的高粱组织培养体系提供参考。     

香石竹植株再生及基因工程研究进展

本文对香石竹的再生体系、遗传转化体系及其分子育种现状作了较为系统的总结。香石竹的再生体系多以器官直接再生不定芽为主, 而通过愈伤组织和体细胞胚途径再生报道较少。用农杆菌介导法和基因枪法均可建立香石竹遗传转化体系, 但近年来的研究显示农杆菌介导法应用普遍且比较稳定。近年来以延长香石竹瓶插寿命为目标的分子育种研究已取得较大进展, 对其色、香和形等其他重要性状的分子育种也已经起步, 而有关香石竹抗性的分子育种有待进一步开拓。     

香石竹植株再生及基因工程研究进展

本文对香石竹的再生体系、遗传转化体系及其分子育种现状作了较为系统的总结。香石竹的再生体系多以器官直接再生不定芽为主,而通过愈伤组织和体细胞胚途径再生报道较少。用农杆菌介导法和基因枪法均可建立香石竹遗传转化体系,但近年来的研究显示农杆菌介导法应用普遍且比较稳定。近年来以延长香石竹瓶插寿命为目标的分子育种研究已取得较大进展,对其色、香和形等其他重要性状的分子育种也已经起步,而有关香石竹抗性的分子育种有待进一步开拓。     

高粱粒重遗传研究进展

高粱是世界第五大粮食作物,种植并培育高产的高粱品种对缓解世界粮食安全问题具有重要意义。粒重是构成产量的一个重要因素,增加粒重是提高高粱产量的重要途径。粒重是由数量性状基因控制的复杂性状,目前已有部分控制高粱粒重的QTLs(Quantitative trait loci,QTL)被定位,这些QTLs在高粱10条染色体上均有分布。对高粱粒重的遗传特点,粒重的影响因素及粒重QTL定位的研究进展进行了总结和概述,对已定位的高粱粒重QTLs进行了比较分析,查找了水稻和玉米中已克隆的粒重相关基因在高粱中的同源基因,并与高粱粒重QTLs定位区间进行了比较,以期为高粱粒重的分子标记辅助育种及高粱粒重主效QTLs的精细定位及克隆提供依据。     

四倍体高粱与约翰逊草间的亲缘关系分析

本研究以四倍体高粱与约翰逊草为材料,利用SSR分子标记和细胞遗传学方法分析了高粱与约翰逊草间的亲缘关系,SSR分析结果表明,高粱与约翰逊草的遗传背景差异较大,SSR差异位点和相似位点在连锁群上的分布具不平衡性;按照差异引物出现频率高低,将连锁群分为两类：高度差异区和低度差异区。细胞学分析结果表明：（1）双亲及杂交种都是不规则的四倍体遗传群体。（2）花粉母细胞减数分裂中期I,双亲及杂交种染色体配对以二价体和四价体为主,杂交种平均每个细胞二价体数为17．00,四倍体高粱为15．23、约翰逊草为15．83,四价体数分别为0．95,2．15和1．60个。但杂交种减数分裂过程中也出现一定数量的单价体,减数分裂会形成一定比例的非整倍配子。SSR检测结果与细胞学分析结果具有一致性,约翰逊草与高粱的染色体组间存在一定程度的同源性。二者杂交不能形成稳定遗传的双二倍体。     

高梁基因组学研究的新进展

高梁是全球第五大禾谷类作物,在干旱、半干旱地区农业生产中占有权其重要的位置。高梁基因组相对较小(750Mbp),遗传多样性丰富,被认为是禾谷类作物比较基因组学研究的模式基因组之一。近年来,综合运用AFLP等分子标记、BAC文库、EST及cDNA作图和FIsH技术,加速了高梁高分辨率基因组图谱的构建。高梁基因测序、基因功能鉴定和克隆,以及遗传转化,亦取得了长足的进展。高梁特有的多种适应逆境胁迫等优异基因资源的发掘及其在作物改良中的应用前景广阔。     

Molecular genetic analysis of the soriz genome (<Emphasis Type="Italic">Sorghum oryzoidum</Emphasis>)

A molecular genetic analysis of soriz genotypes (Sorghum oryzoidum), its parental form Sorghum bicolor (L.) Moench (grain sorghum), possible parents (Sorghum sudanense (Piper.) Stapf. (Sudan grass) and Oryza sativa L. (Rice planting), as well as its closest relatives, has been carried out with the use of microsatellite loci of sorghum and rice. Based on the obtained data, the genetic distances were calculated and the examined species were clustered. It was shown that soriz did not carry rice DNA fragments, but its genome contained DNA fragments, which belonged to Sudan grass. This confirms that the origin of soriz is associated with representatives of Sorghum sudanense.     

Domestication to crop improvement: genetic resources for Sorghum and Saccharum (Andropogoneae)

BACKGROUND: Both sorghum (Sorghum bicolor) and sugarcane (Saccharum officinarum) are members of the Andropogoneae tribe in the Poaceae and are each other's closest relatives amongst cultivated plants. Both are relatively recent domesticates and comparatively little of the genetic potential of these taxa and their wild relatives has been captured by breeding programmes to date. This review assesses the genetic gains made by plant breeders since domestication and the progress in the characterization of genetic resources and their utilization in crop improvement for these two related species. GENETIC RESOURCES: The genome of sorghum has recently been sequenced providing a great boost to our knowledge of the evolution of grass genomes and the wealth of diversity within S. bicolor taxa. Molecular analysis of the Sorghum genus has identified close relatives of S. bicolor with novel traits, endosperm structure and composition that may be used to expand the cultivated gene pool. Mutant populations (including TILLING populations) provide a useful addition to genetic resources for this species. Sugarcane is a complex polyploid with a large and variable number of copies of each gene. The wild relatives of sugarcane represent a reservoir of genetic diversity for use in sugarcane improvement. Techniques for quantitative molecular analysis of gene or allele copy number in this genetically complex crop have been developed. SNP discovery and mapping in sugarcane has been advanced by the development of high-throughput techniques for ecoTILLING in sugarcane. Genetic linkage maps of the sugarcane genome are being improved for use in breeding selection. The improvement of both sorghum and sugarcane will be accelerated by the incorporation of more diverse germplasm into the domesticated gene pools using molecular tools and the improved knowledge of these genomes.     

Retrospective genomic analysis of sorghum adaptation to temperate-zone grain production

Background

Sorghum is a tropical C₄ cereal that recently adapted to temperate latitudes and mechanized grain harvest through selection for dwarfism and photoperiod-insensitivity. Quantitative trait loci for these traits have been introgressed from a dwarf temperate donor into hundreds of diverse sorghum landraces to yield the Sorghum Conversion lines. Here, we report the first comprehensive genomic analysis of the molecular changes underlying this adaptation.

Results

We apply genotyping-by-sequencing to 1,160 Sorghum Conversion lines and their exotic progenitors, and map donor introgressions in each Sorghum Conversion line. Many Sorghum Conversion lines carry unexpected haplotypes not found in either presumed parent. Genome-wide mapping of introgression frequencies reveals three genomic regions necessary for temperate adaptation across all Sorghum Conversion lines, containing the Dw1, Dw2, and Dw3 loci on chromosomes 9, 6, and 7 respectively. Association mapping of plant height and flowering time in Sorghum Conversion lines detects significant associations in the Dw1 but not the Dw2 or Dw3 regions. Subpopulation-specific introgression mapping suggests that chromosome 6 contains at least four loci required for temperate adaptation in different sorghum genetic backgrounds. The Dw1 region fractionates into separate quantitative trait loci for plant height and flowering time.

Conclusions

Generating Sorghum Conversion lines has been accompanied by substantial unintended gene flow. Sorghum adaptation to temperate-zone grain production involves a small number of genomic regions, each containing multiple linked loci for plant height and flowering time. Further characterization of these loci will accelerate the adaptation of sorghum and related grasses to new production systems for food and fuel.     

Biotechnology: Genetic improvement of sorghum (Sorghum bicolor (L.) Moench)

Summary This report reviews the contributions to the improvement of sorghum (Sorghum bicolor (L.) Moench) through traditional approaches with emphasis on the application of biotechnological methods. Strategies include breeding for higher yield, improved grain quality, and biotic and abiotic stress tolerance. Hybrid development and polyploidy breeding are also discussed. Plant breeders, working in concert with biotechnologists, have developed new powerful tools for plant genetic manipulation and genotype evaluation that will significantly improve the efficiency of plant breeding. Improving sorghum through biotechnology is the latest in a long series of technologies that have been applied to this crop. Five basic tools of technology have been developed for sorghum improvement: (1) in vitro protocols for efficient plant regeneration; (2) molecular markers; (3) gene identification and cloning; (4) genetic engineering and gene transfer technology to integrate desirable traits into the sorghum genome; and (5) genomics and germplasm databases. Reports on studies involving the problems, progress, and prospects for utilizing the biotechnological methods for sorghum improvement are discussed.     

Molecular genetic analysis of soriz genome (Sorghum oryzoidum)

Molecular-genetic analysis of soriz genotypes (Sorghum oryzoidum), its paternal form Sorghum bicolor (L.) Moench (grain sorghum), possible parents (Sorghum sudanense (Piper.) Stapf. (Sudan grass) and Oryza sativa L. (rice planting)) and the nearest relatives has been carried out using microsatellite (MS) loci of sorghum and rice. Based on these data genetic distances have been calculated. It was shown that soriz do not bear DNA fragments of rice, but contains in its genome DNA fragments belonging to the Sudanese grass indicating that the origin of soriz is associated with Sorghum sudanense.     

Gene Flow and its Consequences in Sorghum spp.

Gene flow between crops and their weedy or wild relatives can be problematic in modern agricultural systems, especially if it endows novel adaptive genes that confer tolerance to abiotic and biotic stresses. Alternatively, gene flow from weedy relatives to domesticated crops may facilitate ferality through introgression of weedy characteristics in the progeny. Cultivated sorghum (Sorghum bicolor), is particularly vulnerable to the risks associated with gene flow to several weedy relatives, johnsongrass (S. halepense), shattercane (S. bicolor ssp. drummondii) and columbusgrass (S. almum). Johnsongrass and shattercane are common weeds in many sorghum production areas around the world. Sorghum varieties with adaptive traits developed through conventional breeding or novel transgenesis pose agronomic and ecological risks if transferred into weedy/wild relatives. Knowledge of the nature and characteristics of gene flow among different sorghum species is scarce, and existing knowledge is scattered. Here, we review current knowledge of gene flow between cultivated sorghum and its weedy and wild relatives. We further discuss potential avenues for addressing gene flow through genetic, molecular, and field level containment, mitigation and management strategies to facilitate successful deployment of novel traits in this economically important crop species.     

A consensus genetic map of sorghum that integrates multiple component maps and high-throughput Diversity Array Technology (DArT) markers

Background  

Sorghum genome mapping based on DNA markers began in the early 1990s and numerous genetic linkage maps of sorghum have been published in the last decade, based initially on RFLP markers with more recent maps including AFLPs and SSRs and very recently, Diversity Array Technology (DArT) markers. It is essential to integrate the rapidly growing body of genetic linkage data produced through DArT with the multiple genetic linkage maps for sorghum generated through other marker technologies. Here, we report on the colinearity of six independent sorghum component maps and on the integration of these component maps into a single reference resource that contains commonly utilized SSRs, AFLPs, and high-throughput DArT markers.