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.     

Associations between host plant concentrations of selected biochemical nutrients and Mexican rice borer,Eoreuma loftini,infestation

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an economic pest of sugarcane (Saccharum spp. hybrids) and other graminaceous host crops, and it attacks grassy weeds. Oviposition preference has been known to be for plants with leaves that form folds. This study is the first to associate the nutritional quality of crop and forage plant hosts with Mexican rice borer injury. Three experiments were conducted to determine the levels of selected biochemical nutrients, including free amino acids and sugars, in four grass weeds [barnyardgrass, Echinochloa crus‐galli (L.); broadleaf signalgrass, Urochloa platyphylla (Munro ex C. Wright); johnsongrass, Sorghum halepense (L.) Pers.; and Vasey's grass, Paspalum urvillei Steud.], a forage grass [sudangrass, Sorghum bicolor (L.) Moensch spp. drummondi (Nees ex Steud.) de Wet & Harlan], three crop species [maize, Zea mays L.; sorghum, Sorghum bicolor (L.) Moench; and sugarcane, Saccharum spp.], and a sorghum‐sudangrass forage hybrid (all Poaceae). Of 16 free amino acids detected among plants in the first two experiments, only high accumulations of free histidine in sudangrass and maize were associated with increased infestations by Mexican rice borer larvae. In all three experiments, high levels of fructose were associated with heightened Mexican rice borer infestation. Ramifications of these findings on the potential dispersal of this invasive pest in the USA and possible applications of fructose in baits are discussed.     

Multiple methods for the identification of polymorphic simple sequence repeats (SSRs) in sorghum [Sorghum bicolor (L.) Moench]

Simple sequence repeats (SSRs), also known as microsatellites, are highly variable DNA sequences that can be used as markers for the genetic analysis of plants. Three approaches were followed for the development of PCR primers for the amplification of DNA fragments containing SSRs from sorghum [Sorghum bicolor (L.) Moench]: a search for sorghum SSRs in public DNA databases; the use of SSR-specific primers developed in the Poaceae species maize (Zea mays L.) and seashore paspalum grass (Paspalum vaginatum Swartz); and the screening of sorghum genomic libraries by hybridization with SSR oligonucleotides. A total of 49 sorghum SSR-specific PCR primer pairs (two designed from GenBank SSR-containing sequences and 47 from the sequences of genomic clones) were screened on a panel of 17 sorghum and one maize accession. Ten primer pairs from paspalum and 90 from maize were also screened for polymorphism in sorghum. Length polymorphisms among amplification products were detected with 15 of these primer pairs, yielding diversity values ranging from 0.2 to 0.8 with an average diversity of 0.56. These primer pairs are now available for use as markers in crop improvement and conservation efforts.     

Toward integration of comparative genetic, physical, diversity, and cytomolecular maps for grasses and grains, using the sorghum genome as a foundation

The small genome of sorghum (Sorghum bicolor L. Moench.) provides an important template for study of closely related large-genome crops such as maize (Zea mays) and sugarcane (Saccharum spp.), and is a logical complement to distantly related rice (Oryza sativa) as a "grass genome model." Using a high-density RFLP map as a framework, a robust physical map of sorghum is being assembled by integrating hybridization and fingerprint data with comparative data from related taxa such as rice and using new methods to resolve genomic duplications into locus-specific groups. By taking advantage of allelic variation revealed by heterologous probes, the positions of corresponding loci on the wheat (Triticum aestivum), rice, maize, sugarcane, and Arabidopsis genomes are being interpolated on the sorghum physical map. Bacterial artificial chromosomes for the small genome of rice are shown to close several gaps in the sorghum contigs; the emerging rice physical map and assembled sequence will further accelerate progress. An important motivation for developing genomic tools is to relate molecular level variation to phenotypic diversity. "Diversity maps," which depict the levels and patterns of variation in different gene pools, shed light on relationships of allelic diversity with chromosome organization, and suggest possible locations of genomic regions that are under selection due to major gene effects (some of which may be revealed by quantitative trait locus mapping). Both physical maps and diversity maps suggest interesting features that may be integrally related to the chromosomal context of DNA-progress in cytology promises to provide a means to elucidate such relationships. We seek to provide a detailed picture of the structure, function, and evolution of the genome of sorghum and its relatives, together with molecular tools such as locus-specific sequence-tagged site DNA markers and bacterial artificial chromosome contigs that will have enduring value for many aspects of genome analysis.     

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.     

Inheritance of inflorescence architecture in sorghum

The grass inflorescence is the primary food source for humanity, and has been repeatedly shaped by human selection during the domestication of different cereal crops. Of all major cultivated cereals, sorghum [Sorghum bicolor (L.) Moench] shows the most striking variation in inflorescence architecture traits such as branch number and branch length, but the genetic basis of this variation is little understood. To study the inheritance of inflorescence architecture in sorghum, 119 recombinant inbred lines from an elite by exotic cross were grown in three environments and measured for 15 traits, including primary, secondary, and tertiary inflorescence branching. Eight characterized genes that are known to control inflorescence architecture in maize (Zea mays L.) and other grasses were mapped in sorghum. Two of these candidate genes, Dw3 and the sorghum ortholog of ramosa2, co-localized precisely with QTL of large effect for relevant traits. These results demonstrate the feasibility of using genomic and mutant resources from maize and rice (Oryza sativa L.) to investigate the inheritance of complex traits in related cereals.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

The HCN Potential of Chinese Sorghum and Sudangrass Varieties and the Changes of HCN Potential During the Growth of Seedling

In this paper, we measured the HCN potential (HCN-p) of 148 sorghum (Sorghum hicolor (L.) Moench) and sudangrass (Sorghum sudanense) varieties and the changes of HCN-P during seedling growth. The results showed that most of the varieties had their HCN-p more than 1000 ppm (94:59%). Among them, 33.11% belonged to 1400–1600 ppm, 22.97% to 1200–1400 ppm, 17.57% to 1000–1200 ppm, and 14.86% to 1600–1800 ppm. The varieties which HCN-p were less than 1000 ppm or higher than 1800 ppm had a little proportion (11.44%). The varieties with the lowest HCN-p were “Xinliang 80” (672 ppm), “sudancao” (753 ppm), “Huangke Sudancao” (856 ppm), “Limuji” (860 ppm), and “MI03” (876 ppm). Those with the highest HCN-p were “Yuanxin lA” (1967 ppm), “Shisanjie” (1904 ppm), “Mi- bangz” (Da Lai (1900 ppm), “7503 A” (1889 ppm), and Mijia Honggaoliang (1883 ppm). Sudangrass had the lowest HCN-p (about 700 ppm), sweet sorghum had higher HCN-p (about 1500 ppm). with the seedling growth, HCN-p reached its highest value in 4-day-old seedling. The first leaf had the highest HCN-p content, the second leaf and sheath had lower and root had the lowest.     

Seasonal infestations of two stem borers (Lepidoptera: Crambidae) in noncrop grasses of Gulf Coast rice agroecosystems

Infestations of two stem borers, Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) (Lepidoptera: Crambidae), were compared in noncrop grasses adjacent to rice (Oryza sativa L.) fields. Three farms in the Texas rice Gulf Coast production area were surveyed every 6-8 wk between 2007 and 2009 using quadrat sampling along transects. Although D. saccharalis densities were relatively low, E. loftini average densities ranged from 0.3 to 5.7 immatures per m(2) throughout the 2-yr period. Early annual grasses including ryegrass, Lolium spp., and brome, Bromus spp., were infested during the spring, whereas the perennial johnsongrass, Sorghum halepense (L.) Pers., and Vasey's grass, Paspalum urvillei Steud., were infested throughout the year. Johnsongrass was the most prevalent host (41-78% relative abundance), but Vasey's grass (13-40% relative abundance) harbored as much as 62% of the recovered E. loftini immatures (during the winter). Young rice in newly planted fields did not host stem borers before June. April sampling in fallow rice fields showed that any available live grass material, volunteer rice or weed, can serve as a host during the spring. Our study suggests that noncrop grasses are year-round sources of E. loftini in Texas rice agroecosystems and may increase pest populations.     

农杆菌介导Bt基因遗传转化高粱

高粱是全球仅次于小麦、水稻、玉米、大豆和马铃薯等的重要作物之一。以高粱幼穗愈伤组织为转化受体,通过农杆菌介导法和含有抗潮霉素和gus基因的双元载体将杀虫晶体蛋白基因cry1Ab导入高粱品种115、ICS21B和5-27,经Hyg筛选共获得21个独立的转基因株系,52株转基因植株,平均转化率为1.9%。经PCR、Southern杂交和RT-PCR分析表明cry1Ab基因已整合入高粱基因组中并得到正确转录。Bt蛋白Westernblotting分析和ELISA定量测定显示,cry1Ab基因在转基因高粱植株中表达,但不同转基因植株表达量有差异。饲虫试验表明,转基因高粱对大螟(Sesamiainferens)具有一定抗性。     

Chloroplast DNA polymorphism in fertile and male-sterile cytoplasms of sorghum (Sorghum bicolor (L.) Moench)

Summary Restriction endonuclease patterns of chloroplast DNA (cpDNA) were consistently distinguishable between fertile and male-sterile cytoplasms of sorghum [Sorghum bicolor (L.) Moench], whereas no differences in restriction patterns of cpDNA among male-sterile (A₁) lines, including six isocytoplasmic strains, were revealed in this study. It is suggested that chloroplast DNA may contribute to the male sterility of A₁ lines used currently in hybrid sorghum production.This research was supported by a research grant from Kansas Grain Sorghum Commission, Kansas Board of Agriculture. Contribution 90-293-J from the Kansas Agricultural Experiment Station     

Genetic diversity of sorghum accessions resistant to greenbugs as assessed with AFLP markers.

Sorghum, Sorghum bicolor (L.) Moench, is the fifth most important cereal crop grown worldwide and the fourth in the United States. Greenbug, Schizaphis graminum (Rondani), is a major insect pest of sorghum with several biotypes reported to date. Greenbug biotype I is currently the most prevalent and most virulent on sorghum plants. Breeding for resistance is an effective way to control greenbug damage. A successful breeding program relies in part upon a clear understanding of breeding materials. However, the genetic diversity and relatedness among the greenbug biotype I resistant accessions collected from different geographic origins have not been well characterized, although a rich germplasm collection is available. In this study, 26 sorghum accessions from 12 countries were evaluated for both resistance to greenbug biotype I and genetic diversity using fluorescence-labeled amplified fragment length polymorphism (AFLP). Twenty-six AFLP primer combinations produced 819 polymorphic fragments indicating a relatively high level of polymorphism among the accessions. Genetic similarity coefficients among the sorghum accessions ranged from 0.69 to 0.90. Cluster analysis indicated that there were two major groups based on polymorphic bands. This study has led to the identification of new genetic sources of sorghum with substantial genetic variation and distinct groupings of resistant accessions that have the potential for use in the development of durable greenbug resistant sorghum.     

Seventy million years of concerted evolution of a homoeologous chromosome pair, in parallel, in major Poaceae lineages

Whole genome duplication ~70 million years ago provided raw material for Poaceae (grass) diversification. Comparison of rice (Oryza sativa), sorghum (Sorghum bicolor), maize (Zea mays), and Brachypodium distachyon genomes revealed that one paleo-duplicated chromosome pair has experienced very different evolution than all the others. For tens of millions of years, the two chromosomes have experienced illegitimate recombination that has been temporally restricted in a stepwise manner, producing structural stratification in the chromosomes. These strata formed independently in different grass lineages, with their similarities (low sequence divergence between paleo-duplicated genes) preserved in parallel for millions of years since the divergence of these lineages. The pericentromeric region of this homeologous chromosome pair accounts for two-thirds of the gene content differences between the modern chromosomes. Both intriguing and perplexing is a distal chromosomal region with the greatest DNA similarity between surviving duplicated genes but also with the highest concentration of lineage-specific gene pairs found anywhere in these genomes and with a significantly elevated gene evolutionary rate. Intragenomic similarity near this chromosomal terminus may be important in hom(e)ologous chromosome pairing. Chromosome structural stratification, together with enrichment of autoimmune response-related (nucleotide binding site-leucine-rich repeat) genes and accelerated DNA rearrangement and gene loss, confer a striking resemblance of this grass chromosome pair to the sex chromosomes of other taxa.     

转高粱C4型NADP-ME基因水稻植株的光合生理特征

NADP-苹果酸酶(NADP-ME)是C4型植物C4光合途径的一个关键酶。利用RT-PCR结合筛选cDNA文库技术,分离得到了编码高粱(SorghumvulgareL.)C4型NADP-ME的全长cDNA。该cDNA全长为2139bp,其开放可读框为1911bp,共编码636个氨基酸和一个终止密码子(GenBank登陆号为AY274836)。利用农杆菌介导的转化系统将其转入水稻品种“农垦58”。经Southern杂交、Northern杂交和酶活性检测表明,高粱C4型NADP-ME可以在水稻中有效表达,酶活性可被提高1~7倍。对转基因水稻进行光合生理检测表明,转NADP-ME基因水稻CO2交换特征没有明显改变,但是在中午强光条件下光抑制加剧。     

Retrotransposon-related DNA sequences in the centromeres of grass chromosomes.

Several distinct DNA fragments were subcloned from a sorghum (Sorghum bicolor) bacterial artificial chromosome clone 13I16 that was derived from a centromere. Three fragments showed significant sequence identity to either Ty3/gypsy- or Ty1/copia-like retrotransposons. Fluorescence in situ hybridization (FISH) analysis revealed that the Ty1/copia-related DNA sequences are not specific to the centromeric regions. However, the Ty3/gypsy-related sequences were present exclusively in the centromeres of all sorghum chromosomes. FISH and gel-blot hybridization showed that these sequences are also conserved in the centromeric regions of all species within Gramineae. Thus, we report a new retrotransposon that is conserved in specific chromosomal regions of distantly related eukaryotic species. We propose that the Ty3/gypsy-like retrotransposons in the grass centromeres may be ancient insertions and are likely to have been amplified during centromere evolution. The possible role of centromeric retrotransposons in plant centromere function is discussed.     

Biotypic diversity in greenbug (Hemiptera: Aphididae): characterizing new virulence and host associations

Biotypic diversity of the greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), was assessed among populations collected from cultivated wheat, Triticum aestivum L., and sorghum, Sorghum bicolor (L.) Moench, and their associated noncultivated grass hosts. Greenbugs were collected during May through August 2002 from 30 counties of Kansas, Nebraska, Oklahoma, and Texas. Discounting the presumptive biotype A, five of the remaining nine letter-designated greenbug biotypes were collected; however, biotypes C, F, J, and K were not detected. Biotypes E and I exhibited the greatest host range and were the only biotypes collected in all four states. Sixteen greenbug clones, collected from eight plant species, exhibited unique biotype profiles. Eleven were collected from noncultivated grasses, three from wheat, and two from sorghum. The most virulent biotypes were collected from noncultivated hosts. The great degree of biotypic diversity among noncultivated grasses supports the contention that the greenbug species complex is composed of host-adapted races that diverged on grass species independently of, and well before, the advent of modern agriculture.     

WATER RELATIONS OF WATER-STRESSED,SPLIT-ROOT C4 (SORGHUM BICOLOR; POACEAE) AND C3 (HELIANTHUS ANNUUS; ASTERACEAE) PLANTS

Sorghum [Sorghum bicolor (L.) Moench] and sunflower (Helianthus annuus L.) were grown in a greenhouse with roots divided between sand irrigated with nutrient solution (–0.097 MPa) or nutrient solution containing polyethylene glycol (PEG) (–0.570 MPa) to compare the effect of unequal root zone stress on plant water relations of a C₄ (sorghum) and a C₃ (sunflower) plant. Roots also were divided between two pots of sand irrigated only with nutrient solution (controls) or only with PEG in nutrient solution. In addition to plant water-status measurements, photosynthetic rate, growth (height, root, and shoot dry weights), and evolution of ethylene (a gaseous hormone indicative of stress) were measured. Under all three split-root treatments, sunflower had a lower leaf water potential and produced more ethylene than sorghum. Sunflower was able to survive the PEG stress if half of its root system was under nonstressed conditions. Sunflower with half its root system irrigated with PEG usually had values of leaf water potential, osmotic potential, stomatal resistance, transpiration rate, photosynthetic rate, ethylene evolution, height, and dry weights that were close to those of the control plants. Sunflower with all roots exposed to PEG was wilted severely. Sorghum was little affected by PEG stress applied either to half or all the root system. Growth of sorghum was the same under all treatments. Apparently because stomata of sorghum were more closed in the partial stress test than those of sunflower, sorghum conserved water and had a higher leaf water potential, which might have permitted growth with stress.     

Hormonal control of grass inflorescence development

Grass inflorescences produce the grain that feeds the world. Compared to eudicots such as Arabidopsis (Arabidopsis thaliana), grasses have a complex inflorescence morphology that can be explained by differences in the activity of axillary meristems. Advances in genomics, such as the completion of the rice (Oryza sativa) and sorghum (Sorghum bicolor) genomes and the recent release of a draft sequence of the maize (Zea mays) genome, have greatly facilitated research in grasses. Here, we review recent progress in the understanding of the genetic regulation of grass inflorescence development, with a focus on maize and rice. An exciting theme is the key role of plant growth hormones in inflorescence development.     

Variation in levels of lipid components and protein in ecogeographic races of Sorghum bicolor

Sorghum bicolor (L.) Moench is a widespread grass of the African savanna. It contains wild and cultivated subspecies which have morphologically distinct ecogeographic races. Measurements of the amount of oil and protein in sorghum grains revealed significant differences in protein levels between wild and cultivated subspecies. Measurements of the relative percentages of fatty acid components of oil also revealed significant differences in levels of oleic and linoleic acid among wild and cultivated races. We conclude that morphological differences acquired in the course of differentiation of ecogeographic races have been paralleled by differentiation in levels of lipid components and grain protein levels.