Analysis of the seed dispersal patterns of wild soybean as a reference for vegetation management around genetically modified soybean fields

There are concerns that genetically modified soybean might threaten the genetic diversity of the wild soybean populations that are distributed in East Asia because genetically modified soybean has no crossing barrier with wild soybean. A simple and effective method to prevent hybridization via pollen flow is spatial separation between the two species because their hybridization occurs only when they grow in close proximity. Therefore, the invasiveness of wild soybean needs to be known in order to secure the appropriate distances. As wild soybean seeds are dispersed mechanically by pod dehiscence, an experiment was conducted in which white sheets were placed on the ground, concentric circles were drawn around the parent plants, and the number of dispersed seeds within each 0.5 m‐wide zone were counted. About 40% of the produced seeds were dispersed and the number of dispersed seeds gradually declined as the distance from the parent plants increased. The model that explained the relationship between the number and distance of the dispersed seeds was produced by using a generalized linear model procedure. More than 95, 99, and 99.9% of the produced seeds stayed within 3.5, 5.0, and 6.5 m after natural pod dehiscence. Knowing these values is useful for evaluating the level of invasive risk by mechanical seed dispersal. The goal of the work is to efficiently and deliberately prevent hybridization by isolating genetically modified soybean fields and wild soybean populations by vegetation management, including weeding and setting up specific‐width buffer zones.     

Interference between velvetleaf (Abutilon theophrasti Medic.) and soybean (Glycine max (L.) Merr.) I. Growth

Three field experiments were conduced to evaluate the effect of Abutilon theophrasti on dry matter, branching and flowering node, and seed production of soybean. Low populations (2.4–4.7 plants m^?2) of the weed reduced soybean dry matter, flowering node and seed production. The effect was most pronounced on soybean seed yield, and less on flowering node and dry weight production. These effects were due to the presence of A. theophrasti with soybean, and not to changes in plant population. The effect on soybean branching node production was inconsistent between years.     

Deamination of metribuzin in tolerant and susceptible soybean (Glycine max) cultivars

The deamination of metribuzin was studied in vitro in peroxisomes isolated from the leaves of soybean cultivars which were either metribuzin tolerant, intermediate, or sensitive. The deamination rate observed with peroxisomes from tolerant leaves was about twice the rate observed with peroxisomes from sensitive leaves. The intermediate group was also intermediate with respect to the in-vitro deamination rate. Tolerant and sensitive intact soybean plants were pulse-labeled with [¹⁴C]metribuzin via the roots for 5 h. The extractable radioactivity in roots, stems and leaves was measured and separated into metabolites after the 5 h pulse and after an additional 24 h growth in water. The level of DA (deaminated metribuzin) was always significantly higher in the stems and leaves of tolerant soybean plants (4.8–10.0% of the extracted radioactivity) than in sensitive stems and leaves (1.8–2.9%). Conjugates were rapidly formed in tolerant as well as in sensitive soybean tissues. More conjugates were found in the tolerant cultivars, especially after the 5 + 24 h incubation time. Labeled [¹⁴C]DA fed to soybean plants via the roots was conjugated two to four times faster than [¹⁴C]metribuzin. Tolerant soybean tissue conjugated [¹⁴C] DA two to three times faster than sensitive tissue. The results are interpreted as showing that, in tolerant soybean plants, metribuzin is metabolized via deamination and subsequent conjugation, in addition to the well-known direct conjugation of metribuzin parent compound.     

野生大豆(Glycine soja)抗斜纹夜蛾资源鉴定

近年来斜纹夜蛾已发展为影响大豆生产的世界性虫害。对大豆抗斜纹夜蛾种质资源进行鉴定是开展抗虫育种的基础。野生大豆是栽培大豆祖先种,遗传多样性远远超过栽培大豆,从野生种质中发掘斜纹夜蛾抗性资源可以拓宽抗虫育种遗传基础。采用室内喂养斜纹夜蛾幼虫的方法,以幼虫重和蛹重为指标,鉴定了35份野生大豆和20份栽培大豆对斜纹夜蛾的抗性。结果显示:不同种质饲喂下,幼虫重、蛹重和幼虫历期在种质间差异极显著,遗传变异幅度较大,幼虫重和蛹重极显著相关。采用标准品种分级法对抗性鉴定结果进行划分,从55份供试资源中筛选出6份高抗种质,均来自野生大豆;5份高感材料,1份来自野生大豆。本研究为大豆抗斜纹夜蛾育种提供了原始材料,同时有助于大豆抗虫遗传研究与新基因发现。     

Susceptibility of wild carrot (Daucus carota ssp. carota) to Sclerotinia sclerotiorum

Sclerotinia soft rot, caused by Sclerotinia sclerotiorum, is a severe disease of cultivated carrots (Daucus carota ssp. sativus) in storage. It is not known whether Sclerotinia soft rot also affects wild carrots (D. carota ssp. carota), which hybridise and exchange genes, among them resistance genes, with the cultivated carrot. We investigated the susceptibility of wild carrots to S. sclerotiorum isolates from cultivated carrot under controlled and outdoor conditions. Inoculated roots from both wild and cultivated plants produced sclerotia and soft rot in a growth chamber test. Two isolates differed significantly in the ability to produce lesions and sclerotia on roots of both wild carrots and cv. Bolero. Flowering stems of wild carrots produced dry, pale lesions after inoculation with the pathogen, and above-ground plant weight was significantly reduced 4 weeks after inoculation in a greenhouse test. Wild and cultivar rosette plants died earlier and fewer plants survived when inoculated with the pathogen under outdoor test conditions. Cultivar plants died earlier than wild plants, but survived as frequently. Plants inoculated in the crown died earlier and at a lower frequency than plants inoculated on leaves. Wild carrots may thus serve as a host of S. sclerotiorum and thus eventually benefit from any uptake of resistance genes, among them transgenes, via introgression from cultivated carrots.     

Effects of shading and soybean Glycine max (L.) interference on Solanum ptycanthum (Dun.) (eastern black nightshade) growth and development

Summary. Solanum ptycanthum (Dun.) vegetative and reproductive growth was evaluated under shade and in the field with soybean interference. In full sunlight without soybean interference, a S. ptycanthum plant produced 243 g shoots and 5957 berries in 20 weeks, but only 38 g and 576 berries in 11 weeks. Plants grown in 94% shade produced 3 g of shoots and 23 berries in 20 weeks, and 1 g and 1 berry in 11 weeks. S. ptycanthum plants that emerged with the soybeans and were positioned between 75-cm rows produced 43 g shoots and 264 berries, whereas plants positioned in 75-cm rows and emerging 6 weeks after the soybeans produced 1 g and 16 berries. When grown between 37·5-cm rows for the same period of time this weed produced 12 g and 2 berries plant⁻¹; plants positioned in 37·5-cm rows produced shoots less than 1 g in weight and one berry plant⁻¹. Shoot growth and berry production of S. ptycanthum increased from 80 to 200% in a 2-week period between the initiation of soybean leaf abscission and maturity. In a season about 50 000 seeds weed⁻¹ were produced in full sunlight; 20 000 or less were produced under soybean interference. When grown in irradiance levels from full sunlight to 94% shade, viable seeds were first detected 10 days after anthesis and essentially all seeds in the berry were viable 24 days after anthesis     

干旱胁迫对野生及栽培大豆幼苗生理特性及抗氧化酶活性的影响

采用盆栽试验,研究了干旱胁迫对野生及栽培大豆生理特性及抗氧化酶活性的影响。即用相对含水量分别为80%、70%、60%、50%、40%、30%的土壤分别栽种野生大豆和栽培大豆,测定其根系活力、细胞膜透性、超氧化物歧化酶（SOD）活性、过氧化氢酶(CAT)活性、过氧化物酶(POD)活性及丙二醛（MDA）含量。结果表明：在同样的土壤相对含水量以及干旱胁迫程度下,相对于栽培大豆,野生大豆表现出高根系活力和抗氧化酶活性以及低细胞膜透性和丙二醛含量。由此可以说明野生大豆的抗干旱能力高于栽培大豆。     

Potential gene flow from transgenic rice (Oryza sativa L.) to different weedy rice (Oryza sativa f. spontanea) accessions based on reproductive compatibility

BACKGROUND: The possibility of gene flow from transgenic crops to wild relatives may be affected by reproductive capacity between them. The potential gene flow from two transgenic rice lines containing the bar gene to five accessions of weedy rice (WR1–WR5) was determined through examination of reproductive compatibility under controlled pollination. RESULTS: The pollen grain germination of two transgenic rice lines on the stigma of all weedy rice, rice pollen tube growth down the style and entry into the weedy rice ovary were similar to self‐pollination in weedy rice. However, delayed double fertilisation and embryo abortion in crosses between WR2 and Y0003 were observed. Seed sets between transgenic rice lines and weedy rice varied from 8 to 76%. Although repeated pollination increased seed set significantly, the rank of the seed set between the weedy rice accessions and rice lines was not changed. The germination rates of F₁ hybrids were similar or greater compared with respective females. All F₁ plants expressed glufosinate resistance in the presence of glufosinate selection pressure. CONCLUSIONS: The frequency of gene flow between different weedy rice accessions and transgenic herbicide‐resistant rice may differ owing to different reproductive compatibility. This result suggests that, when wild relatives are selected as experimental materials for assessing the gene flow of transgenic rice, it is necessary to address the compatibility between transgenic rice and wild relatives. Copyright © 2009 Society of Chemical Industry     

Effect of amitrole and 2,4-D applied preplant and pre-emergence in soybean (Glycine max)

There is limited information on the effect of amitrole and 2,4-D ester applied preplant and pre-emergence in soybean (G lycine max L.) in Ontario, Canada. Six field trials were conducted over a 2 year period (2004 to 2005) at three Ontario locations to evaluate the response of soybean to amitrole or 2,4-D ester applied at 14 days preplant (DPP), 7 DPP, 1 day after planting (DAP), and 7 DAP. The application of amitrole resulted in as much as 5.8, 3.9, 1.7, and 1% visible crop injury in soybean at 7, 14, 28, and 56 days after emergence (DAE), respectively. There was no visible injury in soybean with any amitrole treatment at 56 DAE, except for amitrole applied at 7 DAP, which caused 1% visible injury in soybean at 2310 g ha⁻¹. The application of the 2,4-D ester caused ≤8.3, 9.7, 4.6, and 1.3% visible injury in soybean at 7, 14, 28, and 56 DAE, respectively. The visible injury decreased over time. There was no visible injury in soybean with any of the 2,4-D ester treatments at 56 DAE, except for the 2,4-D ester treatment applied at 7 DAP, which caused 1% visible injury at 1155 g ha⁻¹ and 1.3% visible injury at 2310 g ha⁻¹. Soybean generally responded similarly to amitrole and 2,4-D ester when applied at 14 and 7 DPP; however, soybean was more tolerant to amitrole compared to 2,4-D ester when applied at 1 or 7 DAP. The application of amitrole and 2,4-D ester resulted in no biomass or yield reduction in soybean compared to the weed-free, untreated control at all doses and application timings evaluated. Soybean is tolerant to the preplant and pre-emergence application of amitrole or 2,4-D ester at the doses evaluated.     

烟草坏死病毒A大豆分离物的分子鉴定

 对曹琦和濮祖芹早期分离到的烟草坏死病毒大豆分离物的生物学、血清学和外壳蛋白的序列进行了进一步研究。该分离物能侵染8科29种植物, 除系统侵染大豆和本生烟外, 其余寄主均为局部侵染。电镜下病毒粒子呈球状, 直径约28nm。基因组为单组分RNA, 大小约为3.7 kb, 具有2条亚基因组, 分别约为1.6 kb和1.3 kb。外壳蛋白亚基的分子量约为30 kDa。血清学试验表明, 该分离物与TNV柳树分离物的抗血清呈特异反应, 与同属坏死病毒属(Necrovirus)的烟草坏死病毒D(TNV-D)和甜菜黑色焦枯病毒(BBSV)无血清学关系。利用简并引物通过RT-PCR克隆了该分离物的外壳蛋白基因。序列分析表明, 该分离物与烟草坏死病毒A(TNV-A)、TNV-D和TNV-D^H的外壳蛋白分别具有88.77%、45.13%和45.49%的氨基酸序列一致性。因此, 该大豆分离物属于TNV-A的一个新株系, 命名为TNV-A^C。     

Pathogenesis of Alfalfa mosaic virus in Soybean (Glycine max) and Expression of Chimeric Rabies Peptide in Virus-Infected Soybean Plants

ABSTRACT Infection of soybean (Glycine max) plants inoculated with particles of Alfalfa mosaic virus (AlMV) isolate 425 at 12 days after germination was monitored throughout the life cycle of the plant (vegetative growth, flowering, seed formation, and seed maturation) by western blot analysis of tissue samples. At 8 to 10 days after inoculation, the upper uninoculated leaves showed symptoms of virus infection and accumulation of viral coat protein (CP). Virus CP was detectable in leaves, stem, roots, seedpods, and seed coat up to 45 days postinoculation (dpi), but only in the seedpod and seed coat at 65 dpi. No virus accumulation was detected in embryos and cotyledons at any time during infection, and no seed transmission of virus was observed. Soybean plants inoculated with recombinant AlMV passaged from upper uninoculated leaves of infected plants showed accumulation of full-length chimeric AlMV CP containing rabies antigen in systemically infected leaves and seed coat. These results suggest the potential usefulness of plants and plant viruses as vehicles for producing proteins of biomedical importance in a safe and inexpensive manner. Moreover, even the soybean seed coat, treated as waste tissue during conventional processing for oil and other products, may be utilized for the expression of value-added proteins.     

The effect of fentin hydroxide (triphenyltin hydroxide) on soybean [Glycine max (L.) Merr.] and rice (Oryza sativa L.) photosynthesis,respiration, and leaf ultrastructure

Soybean [Glycine max (L.) Merr., cv. Swift] plants at the second trifoliate leaf stage and rice (Oryza sativa L. cv. Starbonnet) plants 25 cm tall were treated with 0, 0.56, and 2.24 kg/ha of fentin hydroxide (triphenyltin hydroxide) to determine the effect of this fungicide on photosynthesis, respiration, and leaf ultrastructure. Photosynthesis and respiration were measured with an infrared CO₂ analyzer in an open flow system prior to fentin hydroxide application and at 4, 24, 48, and 96 hr after treatment with fentin hydroxide. No significant detrimental effects on photosynthesis or respiration were evident in either soybean or rice through 96 hr after treatment. Tissue samples from soybean and rice plants, 9 days after fentin hydroxide application, examined for ultrastructure changes with the transmission electron microscope showed no effect due to the fungicide treatment.     

Interference between velvetleaf (Abutilon theophrasti Medic.) and soybean (Glycine max (L.) Merr.) II. Population dynamics

Two field experiments were conducted to determine the effect of changes in Abutilon theophrasti and soybean population numbers through the growing season on soybean dry weight and seed yields. Whether in mixtures or monoculture, the rate of mortality of both species was constant through the growing season. In general, the greater the initial population of either species the greater the rate of mortality through the growing season. Evidence presented supports the hypothesis that A. theophrasti has the adaptive ability of differential mortality at different populations when in mixed stands with soybean and when grown alone and that soybean lacks this ability when mixed with A. theophrasti. This results in smaller, less productive, individual soybean plants.     

Competition for light between velvetleaf (Abutilon theophrasti) and soybean (Glycine max)

We examined factors affecting conversion of light into dry matter of velvetleaf (Abutilon theophrasti) and soybean (Glycine max) grown in a replacement series near Ames, Iowa, U.S.A. in 1986 and 1987. Velvetleaf was taller than soybean over most of the growing season and had more branches, especially at the top of the canopy. Velvetleaf had greater light interception than soybean in the upper part of the canopy, particularly early and late in the day, although total light interception by canopies of the two species was similar on most sample dates. Velvetleaf had higher light utilization efficiency, or conversion of intercepted light into dry matter, in the middle and later part of the growing season. This combination of traits appears to give velvetleaf an advantage over soybean in competition for light.     

Studies on infection of bean (Phaseolus vulgaris) and soybean (Glycine max) by ascospores of Sclerotinia sclerotiarum

Factors influencing the infection of bean and soybean by ascospores of Sderotinia sclerotiorum were studied. In the absence of an exogenous nutrient source, ascospores on intact host tissues produced a short and usually sub-polar germ-tube but only young host tissues were penetrated by the infection hypha arising from the germinated spore. There was a hypersensitive response by cells to penetration and generally the fungus remained restricted to these cells, though it continued to grow within them. Water-soaked lesions characteristic of successful infections only developed when many individual infection sites coalesced following inoculation with high concentrations of ascospores. Flowers or parts of flowers provided a suitable nutrient base for initial colonization from ascospore inoculum. Mycelium extending from this base initiated infection of intact host surfaces. Pollen stimulated growth from germinating ascospores in vitro and in vivo but did not stimulate infection of bean.     

A replacement series evaluation of competition between velvetleaf (Abutilon theophrasti) and soybean (Glycine max)

We examined relative competition abilities of velvetleaf (Abutilon theophrasti) and soybean (Glycine max) grown in a replacement series near Ames, Iowa, U.S.A. in 1986 and 1987. Relative above ground dry weight of soybean in mixtures was higher than expected from mono culture values early in the growing season but lower than expected later in the season, whereas velvetleaf had higher than expected values later in the season. Velvetleaf depressed seed yield of soybean in all mixtures; relative seed yield of velvetleaf was greater in all mixtures than in monoculture. Relative growth rate (RGR), leaf area ratio (LAR) and net assimilation rate (NAR) of soybean did not differ significantly among mixtures and generally decreased over the growing season. Velvetleaf exhibited no consistent differences among mixtures in RGR, LAR, and NAR. Net assimilation rate of velvetleaf was constant over most of the growing season. Relative growth rate and LAR of velvetleaf were highest early in the season and then progressively declined. Velvetleaf had higher NAR and higher RGR than soybean early in the season; LAR of velvetleaf was lower than LAR of soybean over most of the season. Velvetleaf and soybean did not significantly interfere with each other early in the growing season, but velvetleaf gained resources at the expense of soybean during the middle and later parts of the season.     

Seed-borne fungi detected in consignments of soybean seeds (Glycine max) imported into India

Inspection of 16 017 samples of soybean seeds imported into India from 1978 to 2004 resulted in the detection of 21 pathogens, including Peronospora manshurica which is not present in India. Seed-borne fungi of high economic significance included: Ascochyta sojicola , Botryotinia fuckeliana , Cercospora kikuchii , Colletotrichum dematium , Corynespora cassicola , Diaporthe phaseolorum var . sojae , Fusarium oxysporum, Glomerella cingulata , Glomerella glycines , Macrophomina phaseolina , Nectria haematococca , Passalora sojina , Thanatephorus cucumeris as well as other fungal pathogens for which soybean is not a host such as Alternaria padwickii , Cochliobolus sativus , Fusarium culmorum , Fusarium poae , Glomerella graminicola , Setosphaeria rostrata, Verticillium albo-atrum , etc. Some of the fungi detected have very wide host range. Details are presented on the fungi detected, the countries from which the imported consignments originated, and phytosanitary significance.     

Growth responses of soybean (Glycine max) and sorghum (Sorghum bicolor) to an increase in density of Amaranthus dubius (L.) plants at two temperatures

Plants of soybean (Glycine max) and sorghum (Sorghum bicolor) were grown either alone or in combination with 1, 2, 4, 8 and 16 Amaranthus dubius plants per pot in controlled environment chambers at 31/24 and 25/18°C day/night temperatures. Above-ground dry weights, leaf areas and heights were measured at 17 and 35 days after planting. Growth of both species increased with temperature. At the second harvest, at both temperatures, even one A. dubius plant per pot had a significant effect on growth of the crop species, and the effects of the two highest densities were equivalent. Shoot dry weights of A. dubius plants were significantly lower when grown with soybean than with sorghum at the same conditions. Linear regressions showed that the dry weights of the crop species were more highly correlated with biomass than with numbers of the interfering weeds, and suggest that soybean may be more affected by an increase in abundance of A. dubius than is sorghum.     

Mechanism of cellular absorption of imidazolinones in soybean (Glycine max) leaf discs

The mechanism of uptake of imazapyr, imazethapyr, and imazaquin into soybean leaf discs was determined. Uptake into the leaf discs was linear with respect to external concentration from 10^?8 to 10^?3 M. Metabolic inhibitors and uncouplers (DNP, FCCP, CCCP, NaN₃, NaCN, DCMU) decreased uptake 58 to 85 %. Uptake was also sensitive to temperature, with maximum uptake occurring at 23°C. The Q₁₀ for uptake between 13 and 23°C was 1-7. The uptake of all 3 imidazolinones was sensitive to the pH of the uptake solution. Maximum uptake occurred at pH 4. However, there were differences in the rate of uptake among the three herbicides. Imazaquin was absorbed the most rapidly followed by imazethapyr and then imazapyr. These differences in uptake reflected the differences in the lipophilicity of the chemicals at pH 4 and 7. The apparent K_ow of imazaquin, imazethapyr and imazapyr at pH 4 was 7-7, 1-4, and 0-1, respectively, and at pH 7 was 0-04, 0-02, and 0-004, respectively. Based on these results the mechanism of uptake is probably best explained by ion trapping.     

Gene flow from weedy red rice (Oryza sativa L.) to cultivated rice and fitness of hybrids

BACKGROUND: Gene transfer from weeds to crops could produce weedy individuals that might impact upon the evolutionary dynamics of weedy populations, the persistence of escaped genes in agroecosystems and approaches to weed management and containment of transgenic crops. The present aim was to quantify the gene flowrate from weedy red rice to cultivated rice, and evaluate the morphology, phenology and fecundity of resulting hybrids. Field experiments were conducted at Stuttgart and Rohwer, Arkansas, USA. Twelve red rice accessions and an imazethapyr‐resistant rice (Imi‐R; Clearfield^?) were used. RESULTS: Hybrids between Imi‐R rice × red rice were 138–150 cm tall and flowered 1–5 days later than the rice parent, regardless of the red rice parent. Hybrids produced 20–50% more seed than the rice parent, but had equivalent seed production to the majority of red rice parents. Seeds of all hybrids were red, pubescent and dehisced at maturity. For the majority of hybrids, seed germination was higher than that of the red rice parent. The gene flowrate from red rice to rice was 0.01–0.2% and differed by red rice biotype. The hybrids had higher fecundity and potential competitive ability than the rice parent, and in some cases also the red rice parent. CONCLUSIONS: Red rice plants are vectors of gene flow back to cultivated rice and other weedy populations. The progeny of red rice hybrids from cultivated rice mother plants have higher chances of persistence than those from red rice mother plants. Gene flow mitigation strategies should consider this scenario. Copyright © 2009 Society of Chemical Industry