Characterization of Maize Iranian Mosaic Virus and Comparison with Hawaiian and Other Isolates of Maize Mosaic Virus (Rhabdoviridae)

Maize Iranian mosaic virus (MIMV) was characterized and compared with isolates of Maize mosaic virus (MMV, genus Nucleorhabdovirus, family Rhabdoviridae) in insect transmission, cytopathology and ultrastructure of infected maize cells, virion proteins and serologically. MIMV is naturally transmitted by Ribautodelphax notabilis, a delphacid planthopper, in Iran. In this study, another planthopper, Peregrinus maidis, vector of MMV, transmitted MIMV with an estimated efficiency of 0.4–1.6% following feeding on MIMV‐infected maize plants and 64% following injection of MIMV into the hemolymph, suggesting that P. maidis gut tissues largely blocked MIMV transmission. MIMV and MMV‐HI (Hawaii) induced similar cytopathologies in cells of infected maize leaves, with virions budding through inner nuclear and endoplasmic reticulum membranes. In thin sections, virions of MIMV were significantly shorter than those of MMV‐HI. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis of virions of MIMV, MMV‐HI, MMV‐CR (Costa Rica) and MMV‐FL (Florida) yielded six proteins of which four were identified as the putative G, N, P and M proteins of plant rhabdoviruses. The N, P and M proteins of MIMV migrated faster in gels than those of the MMV isolates indicating a lower molecular weight, whereas the bands corresponding to the G proteins migrated similarly for both viruses. Polyclonal antibodies to MMV‐HI failed to react with virions of MIMV in enzyme‐linked immunosorbent assay (ELISA) and with MIMV proteins in Western blots. In contrast, these antibodies reacted strongly with MMV‐HI and MMV‐FL virions in ELISA and with MMV‐HI, MMV‐CR and MMV‐FL proteins in Western blots. Further, in ELISA, polyclonal antibodies to MMV‐MR (Mauritius) reacted weakly with MIMV virions but strongly with MMV‐HI and MMV‐FL virions. Thus, it is concluded that MIMV is a new virus of the Nucleorhabdovirus genus that may be distantly related to MMV.     

Maize Iranian mosaic virus infection promotes the energy sources of its insect vector,Laodelphax striatellus

Maize Iranian mosaic virus (MIMV, family Rhabdoviridae) causes an important disease in cereal crops in Iran. It is transmitted by the planthopper Laodelphax striatellus in a persistent, propagative manner. In the present study, the effect of MIMV on the energy reserves of L. striatellus was studied by comparing energy contents in viruliferous and non‐viruliferous insects. Results showed that MIMV‐infected male and female adults, and nymphs stored 1.82, 2.24 and 1.7‐fold more total energy reserves than non‐viruliferous individuals. This is consistent with a 2.55‐fold increase of the total energy (sum of energy sources in nymphs and adults) of viruliferous compared to non‐viruliferous specimens. A significant increase in glycogen (2.26‐fold), carbohydrate (2.13‐fold), lipid (1.63‐fold) and protein (1.96‐fold) was documented in viruliferous insects compared to non‐viruliferous insects. Based on these results, we conclude that MIMV enhances the energy reserves of its vector and therefore, may play a vital role in the ecology of L. striatellus.     

Plant virus infection modifies plant pigment and manipulates the host preference behavior of an insect vector

Insect-borne plant viruses may modify the phenotype of their host plants and thus influence the responses of insect vectors. When a plant virus modifies host preference behavior of a vector, it can be expected to influence the rate of virus transmission. In this study, we examined the effect of Maize Iranian mosaic virus (MIMV) infection on host preference behavior of the nymphs and adults of its vector, the small brown planthopper, Laodelphax striatellus Fallén (Hemiptera: Delphacidae), feeding on barley plants (Hordeum vulgare L., Poaceae). We found that both viruliferous nymphs and adults significantly preferred healthy plants, whereas non-viruliferous planthoppers preferred virus-infected barley. Further investigations revealed significant reductions in the chlorophyll and carotenoid contents of infected barley leaves. Based on these results, a possible association between insect host preferences and the pigment contents of the plants was observed. In summary, we suggest that host preference of L. striatellus could be affected by the propagative plant virus, possibly through association of this modification with some phenotypic traits of infected plants. These effects may have a critical impact on MIMV transmission rate, with significant implications for the development of virus epidemics.     

Selective effect of a maize diet in reducing serum and brain tryptophan contents and blood and brain serotonin levels.

The Maize diet used selectively lowers the tryptophan, serotonin and 5-hydroxyindoleacetic acid levels in the central nervous system without affecting catecholamine content. These changes are maximal as early as 48 hours after exposure to the Maize diet. The brain serotonin decrease is reversed to normal when the Maize diet is supplemented with Tryptophan, while nicotinic acid is ineffective. The maize diet seems to be a rapid and selective means of reducing brain serotonin content. The hypothesis that the psychic depression observed in patients with Pellagra may be related to an altered serotonin metabolism is discussed.     

Besprechungen

Book review in this article:
Plant Growth Substances 1970. Proceedings of the 7th International Conference on Plant Growth Substances Held in Canberra, Australia, December 7–11, 1970. Editor: G arr , D. J.
Harpaz, I., Maize Rough Dwarf, a Planthopper Virus Disease affecting Maize, Rice, Small Grains and Grasses.     

玉米转基因方法研究进展

玉米是重要的粮食作物,玉米的遗传转化取得了重大成就,而玉米的遗传转化又是玉米遗传改良的有效手段。总结了玉米转化过程中受体的选择标准,比较了各种转化方式,如：农杆菌介导法、基因枪法、花粉管通道法,并探讨了如何有效地选择转化后的阳性事件。     

农杆菌介导玉米遗传转化体系的研究进展

玉米(Zea maysL.)是世界上三大主要粮食作物之一,至今其遗传转化仍比较困难,目前报道有多种成功的方法,其中农杆菌(Agrobactierium tumefaciens)介导法是当前玉米遗传转化的主要方法。本文综述了农杆菌介导的玉米遗传转化研究的发展历史、存在问题和影响因素等,并对未来发展趋势进行展望。     

Identification of maize lethal necrosis disease causal viruses in maize and suspected alternative hosts through small RNA profiling

Maize lethal necrosis disease (MLND) is a devastating viral disease of maize caused by double infection with Maize chlorotic mottle virus (MCMV) and any one of the Potyviridae family members. Management of MLND requires effective resistance screening and surveillance tools. In this study, we report the use of small RNA (sRNA) profiling to detect MLND causal viruses and further the development of alternative detection markers for use in routine surveillance of the disease-causing viruses. Small RNAs (sRNAs) originating from five viruses namely MCMV, Sugarcane mosaic virus (SCMV), Maize streak virus (MSV), Maize-associated totivirus (MATV) and Maize yellow mosaic virus (MYMV) were assembled from infected maize samples collected from MLND hot spots in Kenya. The expression of the identified viral domains was further validated using quantitative real-time PCR. New markers for the detection of some of the MLND causal viruses were also developed from the highly expressed domains and used to detect the MLND-causative viruses in maize and alternative hosts. These findings further demonstrate the potential of using sRNAs especially from highly expressed viral motifs in the detection of MLND causal viruses. We report the validation of new sets of primers for use in detection of the most common MLND causal viruses MCMV and SCMV in East Africa.     

Invertebrate drift in the regulated River Tees, and an unregulated tributary Maize Beck, below Cow Green dam

SUMMARY. The Cow Green dam was completed in the summer of 1970 and invertebrate drift was sampled below the dam and in an adjacent tributary, Maize Beck, on thirty-one occasions between July 1970 and September 1973. Drift was sampled by pumping river water through a filter. The intake was placed in Maize Beck for the first sample and in the Tees for the second, and so on alternately for the rest of the sampling period. Nets were used on ten occasions, nine of these in winter months and once when the pump broke down. A total of ninety-five taxa were recognized, of which eighty-six occurred in Maize Beck and seventy-one in the Tees. The Tees fauna was dominated numerically and in terms of biomass by a large population of micro-crustaceans originating in the reservoir. Hydra and Naididae also formed a large proportion of the Tees drift but contributed little to the biomass. Ephemeroptera were most abundant in Maize Beck samples. Diptera were abundant in drift catches in both streams with simuliid larvae most numerous in Maize Beck and chironomid larvae most numerous in the Tees. The greatest drift densities of the benthic fauna were observed between April and October; the mean number of organisms per 10 m³ were seventy-three in Maize Beck and 144 in the Tees. The mean densities in winter were very low, respectively two and seventeen per 10 m³ in the two rivers. There was no significant difference between the mean levels of the total bottom fauna (numbers and biomass) in the drift in the two rivers during the period April-October, but vrtnter biomass was significantly greater in the Tees. In July 1970 micro-crustaceans represented 29% (14 per 10 m³) of total drift numbers and 3% (0.7 mg wet-weight per 10 m³) of the biomass, whereas in 1973 they represented 99% of both the numbers (37 670 per 10 m³) and weight (2.2 g wet-weight per 10 m³). The relation between benthos and drift was examined. In the drift Plecoptera and Baetidae were more abundant in Maize Beck than in the Tees. Only Chironomidae and Nais spp. were more abundant in the Tees, In the benthos the density of Plecoptera and Baetidae was not significantly different in the two rivers, but all other groups with the exception of Simuliidae occurred at greater densities in the Tees. The proportion of baetids present in the drift was greatest in Maize Beck. No such difference was demonstrated for total fauna. Diel rhythms were observed in baetids and simuhids with densities greater in night catches. Nocturnal peaks of these organisms were less pronounced in the Tees. Chironomid larvae showed no diel changes in abundance. Significant diel changes in the mean weights of individual animals were not detected in baetid nymphs or chironomids. Micro-crustaceans showed no nocturnal peaks of abundance. Preliminary observations on the quality and quantity of seston caught in drift samples between April and October showed great differences between the rivers. In the Tees the bulk ofeach sample consisted of algal filaments derived from the river and micro-crustaceans from the reservoir. In Maize Beck algae were un-common and the sample was composed of peat and mineral particles. Data are presented on seston output at different discharges.     

Downstream changes in the composition,numbers and biomass of bottom fauna in the Tees below Cow Green Reservoir and in an unregulated tributary Maize Beck,in the first five years after impoundment

Changes in composition, numbers and biomass of benthic fauna of the Tees below Cow Green Reservoir and an unregulated tributary Maize Beck were followed between 1972 and 1975 and pre- and post-impoundment conditions were compared. Species diversity was lowest just below the dam and numbers and biomass were highest 240 m downstream of the dam. Faunal densities increased in the Tees after impoundment but in Maize Back no major changes were observed.Freshwater Biological Association, Cow Green UnitFreshwater Biological Association, Cow Green Unit     

玉米转基因研究进展

玉米的转基因研究是国内外植物分子生物学研究的热点之一。自1990年以来,玉米转基因研究取得了显著进展,目前已有转基因的抗虫、抗除草剂玉米杂交种进入商品化生产。从玉米转化受体系统、转化方法、筛选方法以及外源基因在转基因后代中的遗传表达等方面,论述了玉米转基因研究方面的最新研究进展。     

因子分析和聚类分析在玉米品种资源分类上的应用

本研究对201份湖北省玉米品种资源的28个性状进行了因子分析,结果前7个公因子对变异的累计方差贡献率达79.4％,前7个独立的公因子真实地反了所控制的28个性状及其相互关系．以前7个公因子为综合指标进行系统聚类,201份玉米品种聚成12类,其中A,B,H,K类综合性状较好．     

Maize genome in motion

A report on the Maize Genetics Conference held in Washington DC, USA, 27 February-1 March, 2008.     

Genomic,chromosomal and allelic assessment of the amazing diversity of maize

A report on the 46th Annual Maize Genetics Conference, Mexico City, Mexico, 11-14 March 2004.     

Dinitrophenol-induced efflux of sucrose from maize scutellum cells

Maize scutellum slices accumulated sucrose during incubation in glucose, fructose or sucrose. Sucrose was accumulated in two compartments, tentatively     

High-value products from transgenic maize

Maize (also known as corn) is a domesticated cereal grain that has been grown as food and animal feed for tens of thousands of years. It is currently the most widely grown crop in the world, and is used not only for food/feed but also to produce ethanol, industrial starches and oils. Maize is now at the beginning of a new agricultural revolution, where the grains are used as factories to synthesize high-value molecules. In this article we look at the diversity of high-value products from maize, recent technological advances in the field and the emerging regulatory framework that governs how transgenic maize plants and their products are grown, used and traded.     

Corn in Clay: Maize Paleoethnobotany in Pre-Columbian Art

Corn in Clay: Maize Paleoethnobotany in Pre-Columbian Art. Mary W. Eubanks. Gainesville: University Press of Florida, 1999. 249 pp.     

玉米遗传转化系统的研究进展

本文介绍了近年来玉米遗传转化系统的建立、基因导入手段、方法等方面的研究进展。 Abstract：This review introduced the research process of the establishement of genetic transformation system in Maize. The method and integration and expression of exogenous genes were also discussed.     

Dynamics of Zea mays transcriptome in response to a polyphagous herbivore,Spodoptera litura

Functional & Integrative Genomics - Zea mays defense response is well-crafted according to the physical and chemical weapons utilized by their invaders during the coevolutionary period. Maize...