Effects of the semi-dwarfing sdw1/denso gene in barley

Recent advances in cereal genomics have made it possible to analyse the architecture of cereal genomes and their expressed components, leading to an increase in our knowledge of those genes that are associated with the key agronomical traits. Presently, use of a dwarfing gene in breeding process is crucial for the development of modern cultivars. In barley, more than 30 types of dwarfs or semi-dwarfs have been hitherto described. However, only a few of them have been successfully used in barley breeding programs. Both breeding and molecular mapping experiments were undertaken to enhance and evaluate the performance of semi-dwarf barley lines. The semi-dwarfing cultivars had improved lodging resistance and a higher harvest index. There have been a lot of investigations that have contributed new information to our basic understanding of the mechanisms underlying growth regulations in barley. This paper reviews semi-dwarfing genes in barley in general and special attention is paid to mapping of the sdw1/denso locus, changes in protein abundance and associations of the semi-dwarfness with gibberellins.     

Towards molecular breeding of reproductive traits in cereal crops

The transition from vegetative to reproductive phase, flowering per se , floral organ development, panicle structure and morphology, meiosis, pollination and fertilization, cytoplasmic male sterility (CMS) and fertility restoration, and grain development are the main reproductive traits. Unlocking their genetic insights will enable plant breeders to manipulate these traits in cereal germplasm enhancement. Multiple genes or quantitative trait loci (QTLs) affecting flowering (phase transition, photoperiod and vernalization, flowering per se ), panicle morphology and grain development have been cloned, and gene expression research has provided new information about the nature of complex genetic networks involved in the expression of these traits. Molecular biology is also facilitating the identification of diverse CMS sources in hybrid breeding. Few Rf (fertility restorer) genes have been cloned in maize, rice and sorghum. DNA markers are now used to assess the genetic purity of hybrids and their parental lines, and to pyramid Rf or tms (thermosensitive male sterility) genes in rice. Transgene(s) can be used to create de novo CMS trait in cereals. The understanding of reproductive biology facilitated by functional genomics will allow a better manipulation of genes by crop breeders and their potential use across species through genetic transformation.     

Retrospective and perspective of rice breeding in China

Breeding is the art and science of selecting and changing crop traits for the benefit of human beings. For several decades, tremendous efforts have been made by Chinese scientists in rice breeding in improving grain yield, nutrition quality, and environmental performance, achieving substantial progress for global food security. Several generations of crop breeding technologies have been developed, for example, selection of better performance in the field among variants (conventional breeding), application of molecular markers for precise selection (molecular marker assisted breeding), and development of molecular design (molecular breeding by rational design). In this review, we briefly summarize the advances in conventional breeding, functional genomics for genes and networks in rice that regulate important agronomic traits, and molecular breeding in China with focuses on high yield, good quality, stress tolerance, and high nutrient-use efficiency. These findings have paved a new avenue for rational design of crops to develop ideal varieties with super performance and productivity.     

大麦基因组和分子育种研究进展

大麦(Hordeum vulgare L.)是世界上重要的谷类作物之一,其二倍体特性使其成为麦类作物基因组研究的重要材料。随着大量分子标记图谱、BACs文库、突变集合和DNA阵列技术的应用,大麦基因组测序工作已不断深入,越来越多的大麦基因组信息使综合分析大麦基因组结构和功能,了解基因表达网络同重要农艺性状之间的关系成为可能。就大麦基因组研究内容,如ESTs系统、物理图谱的构建、功能基因组学研究和大麦分子育种研究作简要综述,为进一步阐述大麦基因组结构和功能特性,提高大麦分子育种能力提供理论依据。     

Recent Progress on Rice Genetics in China

Through thousands of years of evolution and cultivation, tremendously rich genetic diversity has been accumulated in rice （Oryza sativa L.）, developing a large germplasm pool from which people can select varieties with morphologies of Interest and other important agronomic traits. With the development of modern genetics, scientists have paid more attention to the genetic value of these elite varieties and germplasms, and such rich rice resources provide a good foundation for genetic research in China. Approximately 100 000 accessions of radiation-, chemical- or insertion-induced mutagenesis have been generated since the 1980s, and great progress has been made on rice molecular genetics. So far at least 16 variant/mutant genes Including MOC1, BC1, SKC1, and Rfgenes have been isolated and characterized in China. These achievements greatly promote the research on functional genomics, understanding the mechanism of plant development and molecular design breeding of rice in China. Here we review the progress of three aspects of rice genetics in China： moving forward at the molecular level, genetic research on elite varieties and germplasms, and new gene screening and genetic analysis using mutants. The prospects of rice genetics are also discussed.     

燕麦基因组学研究进展

燕麦具有较高的营养价值和保健功能,是一种可用于均衡营养、科学饮食的健康食品,正逐渐受到人们的青睐和认可。基因组学研究有助于燕麦重要农艺性状的定位和克隆,对开发利用燕麦优质种质资源具有重要意义。本文从以下几个方面对燕麦基因组学研究进展进行综述:(1)燕麦属基因组类型、大小及染色体倍性研究;(2)基于多种分子标记手段构建燕麦基因组遗传图谱进展;(3)二倍体、六倍体燕麦基因组测序进展;(4)基于数量性状基因座定位和全基因组关联性分析手段对燕麦基因组功能基因的注释研究;(5)燕麦群体基因组/泛基因组学研究。同时对燕麦基因组学研究方向进行了探讨,以期为今后燕麦遗传育种提供参考信息。     

Advances in Arachis genomics for peanut improvement

Peanut genomics is very challenging due to its inherent problem of genetic architecture. Blockage of gene flow from diploid wild relatives to the tetraploid; cultivated peanut, recent polyploidization combined with self pollination, and the narrow genetic base of the primary genepool have resulted in low genetic diversity that has remained a major bottleneck for genetic improvement of peanut. Harnessing the rich source of wild relatives has been negligible due to differences in ploidy level as well as genetic drag and undesirable alleles for low yield. Lack of appropriate genomic resources has severely hampered molecular breeding activities, and this crop remains among the less-studied crops. The last five years, however, have witnessed accelerated development of genomic resources such as development of molecular markers, genetic and physical maps, generation of expressed sequenced tags (ESTs), development of mutant resources, and functional genomics platforms that facilitate the identification of QTLs and discovery of genes associated with tolerance/resistance to abiotic and biotic stresses and agronomic traits. Molecular breeding has been initiated for several traits for development of superior genotypes. The genome or at least gene space sequence is expected to be available in near future and this will further accelerate use of biotechnological approaches for peanut improvement.     

Toward understanding genetic mechanisms of complex traits in rice

Rice is the primary carbohydrate staple cereal feeding the world population. Many genes, known as quantitative trait loci (QTLs), con-trol most of the agronomically important traits in rice. The identification of QTLs controlling agricultural traits is vital to increase yield and meet the needs of the increasing human population, but the progress met with challenges due to complex QTL inheritance. To date,many QTLs have been detected in rice, including those responsible for yield and grain quality; salt, drought and submergence tolerance;disease and insect resistance; and nutrient utilization efficiency. Map-based cloning techniques have enabled scientists to successfully fine map and clone approximately seventeen QTLs for several traits. Additional in-depth functional analyses and characterizations of these genes will provide valuable assistance in rice molecular breeding.     

High-Throughput Genomics Enhances Tomato Breeding Efficiency

Tomato (Solanum lycopersicum) is considered a model plant species for a group of economically important crops, such as potato, pepper, eggplant, since it exhibits a reduced genomic size (950 Mb), a short generation time, and routine transformation technologies. Moreover, it shares with the other Solanaceous plants the same haploid chromosome number and a high level of conserved genomic organization. Finally, many genomic and genetic resources are actually available for tomato, and the sequencing of its genome is in progress. These features make tomato an ideal species for theoretical studies and practical applications in the genomics field. The present review describes how structural genomics assist the selection of new varieties resistant to pathogens that cause damage to this crop. Many molecular markers highly linked to resistance genes and cloned resistance genes are available and could be used for a high-throughput screening of multiresistant varieties. Moreover, a new genomics-assisted breeding approach for improving fruit quality is presented and discussed. It relies on the identification of genetic mechanisms controlling the trait of interest through functional genomics tools. Following this approach, polymorphisms in major gene sequences responsible for variability in the expression of the trait under study are then exploited for tracking simultaneously favourable allele combinations in breeding programs using high-throughput genomic technologies. This aims at pyramiding in the genetic background of commercial cultivars alleles that increase their performances. In conclusion, tomato breeding strategies supported by advanced technologies are expected to target increased productivity and lower costs of improved genotypes even for complex traits.Key Words: Solanum lycopersicum, genetic and genomic resources, molecular markers, microarray, resistance to pathogens, fruit quality.     

Marker assisted selection in crop plants

Genetic mapping of major genes and quantitative traits loci (QTLs) for many important agricultural traits is increasing the integration of biotechnology with the conventional breeding process. Exploitation of the information derived from the map position of traits with agronomical importance and of the linked molecular markers, can be achieved through marker assisted selection (MAS) of the traits during the breeding process. However, empirical applications of this procedure have shown that the success of MAS depends upon several factors, including the genetic base of the trait, the degree of the association between the molecular marker and the target gene, the number of individuals that can be analyzed and the genetic background in which the target gene has to be transferred. MAS for simply inherited traits is gaining increasing importance in breeding programs, allowing an acceleration of the breeding process. Traits related to disease resistance to pathogens and to the quality of some crop products are offering some important examples of a possible routinary application of MAS. For more complex traits, like yield and abiotic stress tolerance, a number of constraints have determined severe limitations on an efficient utilization of MAS in plant breeding, even if there are a few successful applications in improving quantitative traits. Recent advances in genotyping technologies together with comparative and functional genomic approaches are providing useful tools for the selection of genotypes with superior agronomical performancies.     

Molecular approaches in pig breeding to improve meat quality.

This article reviews the advances in molecular genetics that have led to the identification of genes and markers associated with meat quality in pig. The development of a considerable number of annotated livestock genome sequences represents an incredibly rich source of information that can be used to identify candidate genes responsible for complex traits and quantitative trait loci effects. In pig, the huge amount of information emerging from the study of the genome has helped in the acquisition of new knowledge concerning biological systems and it is opening new opportunities for the genetic selection of this specie. Among the new fields of genomics recently developed, functional genomics and proteomics that allow considering many genes and proteins at the same time are very useful tools for a better understanding of the function and regulation of genes, and how these participate in complex networks controlling the phenotypic characteristics of a trait. In particular, global gene expression profiling at the mRNA and protein level can provide a better understanding of gene regulation that underlies biological functions and physiology related to the delivery of a better pig meat quality. Moreover, the possibility to realize an integrated approach of genomics and proteomics with bioinformatics tools is essential to obtain a complete exploitation of the available molecular genetics information. The development of this knowledge will benefit scientists, industry and breeders considering that the efficiency and accuracy of the traditional pig selection schemes will be improved by the implementation of molecular data into breeding programs.     

Genome Sequencing and Identification of Gene Function in Rice

Rice is known to be one of the most important crops for human consumption. As the model cereal crop, large-scale sequencing of rice genome must play quite important roles both in theoretical research and practical application in rice breeding, which announces the opening of another new way to resolve the world food crisis. At present, the emphasis of rice genome research has been transferred from structure genomics to functional analysis. The discovery of new genes and annotation of gene function was believed to be an important issue in functional genomics research. In this article, the sequencing and functional research of the rice genome were reviewed. These results may provide some useful clues for rice genetic engineering and breeding practices.     

水稻基因组测序及基因功能的鉴定

水稻是重要的粮食作物。作为单子叶模式植物,水稻基因组的大规模测序具有巨大的理论价值和现实意义。目前已获得了籼稻“93—11”和粳稻“日本晴”高质量的基因组数据,这为在基因组水平上深入研究其生长、发育、抗病和高产等的遗传机理提供了便利,从而为进一步解决世界粮食危机提供了新的突破口和契机。随着水稻基因组计划的顺利结束,其研究重心也已由建立高分辨率的遗传、物理和转录图谱为主的结构基因组学转向基因功能的研究。结构基因组学研究获得的大量序列数据为揭示和开发功能基因开辟了广阔的前景。目前,利用图位克隆和电子克隆等方法已成功分离了多个水稻抗病、抗虫、抗逆境、抗倒伏、高产、优质等重要农艺性状相关的基因,对培育水稻新品种,促进农业的可持续发展意义重大。据估计,水稻至少拥有3．7万个非转座因子相关的蛋白编码基因。因此,完成全基因组序列测定后,重要基因功能的鉴定已成为当前基因组学研究的主要目标。反向遗传学、大规模基因功能表达谱分析和蛋白质组研究等策略已在研究水稻重要基因的功能方面发挥了重要作用。文章综述了水稻基因组测序及基因功能研究的现状,并就新基因发掘和基因功能注释的方法作了评述,期待为水稻遗传工程和育种实践提供参考。     

奶牛重要经济性状全基因组关联分析研究进展

产奶性状是奶牛最重要的生产性状,随着平衡育种理念的提出和发展,繁殖性状、体型性状、健康性状和长寿性等功能性状也逐渐被重视并纳入育种规划中。鉴定产奶性状和功能性状主效基因或遗传标记并将之应用于奶牛标记辅助选择可望加快遗传进展。随着高密度SNP标记的高通量检测技术的发展,全基因组关联分析已成为鉴定畜禽重要经济性状基因的重要途径。文章对奶牛产奶性状和功能性状全基因组关联分析研究进展进行综述。     

Current status and future possibilities of molecular genetics techniques in <Emphasis Type="Italic">Brassica napus</Emphasis>

As PCR methods have improved over the last 15 years, there has been an upsurge in the number of new DNA marker tools, which has allowed the generation of high-density molecular maps for all the key Brassica crop types. Biotechnology and molecular plant breeding have emerged as a significant tool for molecular understanding that led to a significant crop improvement in the Brassica napus species. Brassica napus possess a very complicated polyploidy-based genomics. The quantitative trait locus (QTL) is not sufficient to develop effective markers for trait introgression. In the coming years, the molecular marker techniques will be more effective to determine the whole genome impairing desired traits. Available genetic markers using the single-nucleotide sequence (SNP) technique and high-throughput sequencing are effective in determining the maps and genome polymorphisms amongst candidate genes and allele interactions. High-throughput sequencing and gene mapping techniques are involved in discovering new alleles and gene pairs, serving as a bridge between the gene map and genome evaluation. The decreasing cost for DNA sequencing will help in discovering full genome sequences with less resources and time. This review describes (1) the current use of integrated approaches, such as molecular marker technologies, to determine genome arrangements and interspecific outcomes combined with cost-effective genomes to increase the efficiency in prognostic breeding efforts. (2) It also focused on functional genomics, proteomics and field-based breeding practices to achieve insight into the genetics underlying both simple and complex traits in canola.     

The influence of genetics on future crop production strategies: from traits to genes, and genes to traits

This paper discusses how a genetical approach to plant physiology can contribute to research underpinning the production of new crop varieties. It highlights the interactions between genetics and plant breeding and how the current advances in genetics and the new science of genomics can contribute to our understanding of the genetical control of key agronomic traits ‐ the process of ‘translating’ traits to identified and mapped genes. Advances in genomics, such as the sequencing of whole genomes and expressed sequence tags, are producing information on genes and gene structures, but without knowing their function. A great deal more biology will be necessary to translate gene structure to function ‐ the process of translating genes to traits. Combining these ‘forward’ and ‘reverse’ genetic approaches will allow us to get comprehensive knowledge of the biology of agronomic traits at the physiological, biochemical and molecular levels, so that the ‘circuitry’ of our crop plants can be elucidated. This will enable plant breeders to manipulate crop phenotype using marker‐assisted breeding or genetic engineering approaches with a precision not previously possible.     

The use of molecular genetics in the improvement of agricultural populations

Substantial advances have been made in the genetic improvement of agriculturally important animal and plant populations through artificial selection on quantitative traits. Most of this selection has been on the basis of observable phenotype, without knowledge of the genetic architecture of the selected characteristics. However, continuing molecular genetic analysis of traits in animal and plant populations is leading to a better understanding of quantitative trait genetics. The genes and genetic markers that are being discovered can be used to enhance the genetic improvement of breeding stock through marker-assisted selection.