山药化感物质对山药和玉米种子萌发及幼苗生长的影响

本研究以山药零余子和玉米种子为受体材料,采用生物测试方法,以发芽率、发芽势、发芽指数、根长、茎长和干重为种子萌发和幼苗生长参数,研究山药植株腐解液、根系分泌物和根际土浸提液对受体材料的化感效应,旨在探明山药化感物质的释放途径,探索山药化感物质对不同受体材料的化感作用,为揭示山药连作障碍的机理奠定基础。结果表明：山药植株腐解液和根系分泌物对山药和玉米均有强烈的化感抑制作用,根际土浸提液的化感作用较微弱,化感作用强度为根系分泌物˃植株腐解液˃根际土浸提液,山药根系分泌物和植株腐解液含有丰富的化感物质,可能是山药自毒物质的主要来源之一,是山药化感物质研究的可靠基础材料;在试验设置的浓度范围内,山药化感物质对受体材料的抑制作用与其质量浓度呈正比,3种浸提液对受试材料的化感作用存在低促高抑的浓度效应,低于100 mg/mL时有微弱的促进作用,大于等于100 mg/mL就会产生强烈的抑制作用,随着浓度升高,化感抑制作用强度越大;山药的化感物质对玉米幼苗生长抑制强度大于种子萌发期,山药则相反;结合种子萌发和幼苗生长的综合化感效应指数,2种受试作物对山药化感作用的敏感程度为自毒作用强于他感作用。     

不同秸秆及绿肥浸提液对玉米化感作用的研究

采用室内培养试验,通过测定油菜秸秆、小麦秸秆、紫云英及紫云英+油菜秸秆4种浸提液对玉米发芽、幼苗生长及干重的影响,研究不同秸秆及绿肥对玉米的化感作用。结果表明,当浸提液浓度≥10 g/L时显著降低玉米发芽率。除紫云英+油菜秸秆浸提液对幼苗生长及干重表现为较强抑制作用外,其他浸提液均表现为显著促进作用或微弱抑制作用,紫云英浸提液促进作用最强,其中,油菜秸秆、小麦秸秆、紫云英浸提液均在5 g/L时对幼苗总干重的促进作用最大,分别较对照提高10.85%、11.51%、16.71%。除紫云英+油菜秸秆外,其他秸秆及绿肥对玉米的化感作用整体上均表现为促进作用,油菜秸秆、小麦秸秆、紫云英及油菜+紫云英浸提液的综合敏感指数分别为2.64%、3.59%、10.32%、-7.33%。     

外源DNA导入小麦的分子育种实践

利用花粉管通道法将具有高光合效率的C4植物高粱的DNA导入普通小麦陇春13,成功选育出了高产、抗逆、耐盐碱小麦新品系89122,较原受体增产21.06%,在盐碱地比当地主栽品种V 26增产10.5%,比原受体增产22.5%,光合效率明显提高,通过RAPD鉴定表明,高粱基因组部分片断已经整合到了小麦染色体中。将高粱、玉米、谷子、小麦、长穗偃麦草、大麦、硬粒小麦等33份材料的基因组DNA通过花粉管通道法转入普通小麦,创造了大量具有利用价值的变异材料,同时选育出一系列的小麦新品系,并且应用于生产中。经过表型鉴定、生化分析和分子等水平的综合研究表明,利用花粉管通道法创造的新品系和中间变异材料绝大多数变异性状不以孟德尔规律遗传,而表现为母性遗传特征,这比以农杆菌为代表的单基因转基因技术更具有优越性,对数量形状控制的表型来说更具有意义。     

黑麦6R染色体特异性PCR标记的建立

为了筛选黑麦染色体组特异性分子标记,以荆州黑麦、秦岭黑麦、森林黑麦、非洲黑麦、普通小麦中国春、R25、R111和MY11为材料,用A～M组142个10碱基随机引物进行RAPD扩增.发现引物M04可以在所有黑麦中扩出一条长1 143 bp(经测序)的特异片段OPM041143,而供试小麦材料均未扩出该片段.根据OPM041143设计特异引物M4-F和M4-R.利用M4-F和M4-R对含黑麦染色体的材料和小麦族其它物种进行扩增,结果表明,只有含黑麦染色体的材料均可以扩出一条分子量为1 082 bp的DNA带,命名为PSCM1082.进而利用一套中国春-Imperial黑麦二体附加系和几个小麦-黑麦染色体6R衍生系进行扩增,发现仅含6R染色体的材料能扩增出PSCM1082,这说明PSCM1082是黑麦6R染色体所特有.黑麦6R染色体特异PCR标记PSCM1082的发现,对于快速跟踪检测导入小麦中的6R染色体具有实用价值,可以应用于小麦育种工作中.     

以色列地中海沿岸野生二粒小麦苗期抗条锈性的鉴定与分析

为进一步挖掘新的小麦抗条锈病种质资源基因,利用流行于中国和以色列的4个小麦条锈病生理小种对以色列地中海沿岸相对较湿润的Beit-Oren、Bat-Shelomo以及Givat-Koach地区的野生二粒小麦30个基因型,分别进行了苗期抗条锈性鉴定,并分析其抗锈性差异.结果表明,来源于地中海沿岸3个地区的野生二粒小麦中有7个基因型对不同条锈病生理小种表现出了抗性水平,其中来自于Bat-Shelomo群体的基因型6-22,对国内流行生理小种条中32和以色列流行生理小种5006均表现出了较强的抗性,可作为新抗病基因材料加以研究和利用.     

野生二粒小麦叶绿体基因RNA编辑位点的预测、鉴定与分析

RNA编辑是高等植物叶绿体基因转录后表达调控的一种重要方式。为了解野生二粒小麦叶绿体基因RNA编辑的组成及其与其他麦类作物的异同,通过生物信息学预测结合RT-PCR的方法,对野生二粒小麦叶绿体基因的RNA编辑位点进行了预测和鉴定。生物信息学预测共发现了分布于15个基因上的35个编辑位点,均为C到U的转换,其中ndhB基因包含的编辑位点数量最多,达9个;在此基础上,随机选取5个基因对其编辑位点进行了测序验证,结果共鉴定了18个C→U的编辑位点;进一步对编辑后编码蛋白的二级结构和跨膜结构域进行了预测,发现编辑后所有基因均发生了二级结构的改变,但只有ndhB基因的跨膜结构域发生了改变;最后,将确定的野生二粒小麦叶绿体基因RNA编辑位点与7个禾本科物种的RNA编辑位点进行比较,共发现17个编辑位点在这些种间具有保守性,相比于其他物种,野生二粒小麦与普通小麦和粗山羊草具有更相似的编辑位点组成。     

辽西地区垄作保护性耕作方式对玉米产量效应的影响研究

比较研究了不同垄作保护性耕作方式对玉米产量及其形成过程的影响。结果表明,垄作保护性耕作方式具有明显的增产效果,留茬免耕、留茬覆盖和灭茬免耕分别比传统耕作增产12.0%、13.6%和7.8%。垄作保护性耕作方式的干物质积累量和株高均表现为作物生长发育的前期低于传统耕作,在拔节期以后逐渐赶上并超过传统耕作,其单株干物重由大到小的顺序为:留茬覆盖>留茬免耕>灭茬免耕,平均株高整齐度由大到小的顺序为:灭茬免耕>传统耕作>留茬免耕>留茬覆盖。不同耕作方式玉米灌浆速率不同,其中保护性耕作方式玉米灌浆速率的优势表现在授粉15d以后。垄作保护性耕作方式的玉米穗行数、行粒数均优于传统耕作,其中又以留茬覆盖方式最佳,分别比传统耕作高出0.85和1.40个百分点。     

8个栽培小麦品种的化感差异及其对除草剂药效的影响

为了解陕西关中地区主要栽培小麦品种化感作用的差异及其对除草荆的增效作用,用室内培养皿法和盆栽试验测定了关中麦区8个主要栽培小麦(Triticum aestivum)品种对伴生恶性杂草播娘蒿(Descurainia so-phia)的化感作用,其化感作用强弱依次为小偃6号>陕农981>西农889>秦农142>小偃22>武农148>陕715>西农979,筛选出对播娘蒿种子萌发和幼苗生长具有较强抑制作用的小偃6号和陕农981,并测试了这两个品种对除草荆(2,4-D和10%苯磺隆)药效的影响.结果表明,两种除草荆分别施用于这两个小麦品种的有效中浓度(EC50)均低于对照;与对照品种比较,这两个小麦品种减少一定用量除草剂后仍然可以达到抑制杂草生长的效果.以对播娘蒿幼苗生长抑制90%为指标,小偃6号和陕农981中应用除草剂2,4-D可减少推荐用量25%～30%,应用10%笨磺隆可减少推荐用量27%～32%.而两种除草剂应用于弱化感作用品种西农979时,用量降低不超过5%才能保证90%的防除效果.     

部分小麦种质资源材料对白粉病和锈病的抗性鉴定及分析

为了挖掘新的抗病基因资源,对82份小麦种质材料分别进行了苗期和/或成株期白粉病、秆锈病和条锈病抗性鉴定.结果表明,苗期抗白粉病材料占供试材料的46.34%;抗秆锈病材料占79.03%;抗条锈病材料占53.33%.一粒小麦MO2、MO5、BO1、BO3、BO9、BO104,二粒小麦 PS5,普通小麦黔麦15、沈免2059、捷克G377、丰优3号、Fr81-12 和兰考5号对白粉病和秆锈病均表现抗病.栽培一粒小麦MO5和野生一粒小麦 BO1、BO3、BO9 对三种病害均表现中等以上抗性.对部分材料进行了田间成株期鉴定的结果表明,对秆锈病均表现高抗,与苗期一致;条锈病、白粉病表现与苗期抗性有差别.研究结果说明,供试材料对不同病害的抗性存在明显差异,一粒、二粒小麦对白粉病抗性较好,骨干亲本和外引材料及辽宁省区域试验参试品系对秆锈病抗性较好.     

普通小麦及其近缘物种花序、小穗和小花的形态结构分析

花的发育影响着种子的发育。普通小麦是三大粮食作物之一,但对小麦花序发育的研究滞后于水稻和玉米。为揭示小麦花发育的机理,本研究采用体视镜观察、扫描电子显微镜观察和组织切片后光学显微镜观察等方法,对普通小麦及其近缘物种一粒小麦、拟斯卑尔脱山羊草、粗山羊草、二粒小麦以及二穗短柄草的花序、小穗和小花形态结构进行了系统观察和分析比较。结果表明,普通小麦与二倍体小麦、二粒小麦表现出一定差别:普通小麦每个小穗形成8~10朵小花,但在发育后期,大多数小花退化不育,每个小穗只有3~4朵小花能够形成种子;二倍体小麦和二粒小麦的小穗结构与普通小麦类似,但每个小穗发育形成3~5朵小花,小花数目明显减少。与普通小麦相似,二穗短柄草每个小穗同样分化形成多朵小花,不同的是,二穗短柄草的大多数小花发育正常,是可育的。以上这些研究结果暗示小麦具有巨大的增产潜力。     

Phosphoenolpyruvate carboxylase activity in ear organs is related to protein concentration in grains of winter wheat

The relationship between phosphoenolpyruvate carboxylase (PEPC) activities in flag leaf blade and ear organs (glume and grain) and protein content of grain as well as grain weight after flowering were studied in different winter wheat (Triticum aestivum L.) genotypes. Results showed higher PEPC activity in the developing grain than in flag leaf blade and glume during grain development. For 16 of the genotypes studied, the mean PEPC activity in the developing grain or glume at 15 and 25 days after flowering was significantly and positively correlated with final protein content of grain. Enzyme activities in glume and flag leaf blade were positively correlated with final grain weight but the activity in developing grain was weakly and negatively correlated with grain weight. The overall data suggest that PEPC may be involved in protein biosynthesis during grain development, and it may have an important role in regulating carbon and nitrogen metabolism in the ear of wheat.     

云南、西藏及新疆小麦研究进展

为了解目前云南、西藏和新疆小麦的研究现状,就三者的分类学地位、起源进化、独特性状和遗传多样性的研究进展进行了综述,并提出了进一步研究的问题和意见.分类学,形态学,染色体组组成,SSR分子标记等研究结果表明,云南、西藏小麦是普通小麦的一个亚种,而新疆小麦被划分为六倍体小麦内的一个独立的种(Tr.petropavlovskyio),推测云南小麦和西藏小麦可能是由中东等地传入中国的原始六倍体小麦的后代,而新疆小麦或许是外来原始六倍体小麦传入中国新疆后,再与新疆本地的波兰小麦杂交的后代.研究还表明,西藏小麦和云南小麦群体内的遗传多样性要大于新疆小麦.     

小麦与玉米远缘杂交诱导小麦单倍体的研究

为了研究在小麦×玉米中亲本及2,4-D对诱导小麦单倍体的影响,将36个小麦杂交组合的F1植株与4个玉米品种分别进行远缘杂交,杂交后用50、100、150mg·L-1三种不同浓度的2,4-D溶液处理杂交穗,结果表明,不同小麦杂交组合远缘杂交的得胚率差异显著;不同玉米品种远缘杂交的得胚率总趋势表现为:爆烈玉米(9.9%)>糯玉米(8.9%)>普通玉米(8.2%)>甜玉米(4.6%);2,4-D对小麦单倍体的形成是必须的,且不同浓度之间存在差异,以100mg·L-1浓度处理效果最为理想;同时,2,4-D重复处理的得胚率高于一次处理。     

Screening and Future Exploitation of Allelopathic Plants as Alternative Herbicides with Special Reference to Hairy Vetch

Summary

Allelopathic cover crops are one of the most promising application of allelopathy for weed control and reduce the synthetic herbicides input. Fifty three cover crop plant species (26 leguminous, 19 graminaceous and 8 others) were assessed for the allelopathic activity using Plant Box Method. It was found that leguminous cover crops such as hairy vetch (Vicia villosa) and velvetbean (Mucuna pruriens), graminaceous cover crops, such as oat (Avena sativa) and rye (Secale cereale), certain cultivars of wheat (Triticum aestivum) and barley (Hordeum vulgare) were promising. By bioassay screening, 23 species were selected for field tests. Fall-sown cover crops such as hairy vetch, rye, wheat, oat, grass pea, and mustard are more effective when compared to spring-sown cover crops. Hairy vetch was most promising for the weed control in abandoned fields because of its ability to die off during summer season to make a thick straw-like mulch.     

Allelopathic effects of Ambrosia artemisiifolia L. in the invasive process

Ambrosia artemisiifolia (common ragweed), an annual native to North America, is now present in many European countries where it causes summer hay fever and interferes with several important crops. We investigated if common ragweed invasiveness could be explained by its leaf tissue and root exudate allelopathic potential on indicator crops (alfalfa, barley, maize, lettuce, tomato, and wheat), weeds (Echinochloa crus-galli, Solanum nigrum, Portulaca oleracea, and Digitaria sanguinalis), and common ragweed itself in laboratory and greenhouse conditions. Different residue substrates were prepared for soil incorporation and trials were conducted under both laboratory (1, 2, and 3 g residues/Parker dish) and greenhouse conditions (1.28 g residues/pot). The effect of the preparations on the germination and growth of the indicator crops and weeds were evaluated relative to soil previously used to grow A. artemisiifolia. Results showed tomato was the most sensitive indicator crop species as growth was reduced by more than 50% in both laboratory and greenhouse experiments. Lettuce root and shoot growth were also inhibited, but only when common ragweed residues, and not root exudates, were added to the substrate. Among the weeds, E. crus-galli was not affected by common ragweed while D. sanguinalis suffered a large germination reduction (90%) after incorporation of 3 g of residues. If common ragweed occurred as weed in a field, the cultivation of a less sensitive crop such as winter wheat should be considered before the cultivation of a more susceptible crop.     

茉莉酸甲酯与水杨酸对光温敏雄性不育小麦颖花开闭的调控

为探索雄性不育小麦小花颖壳开闭人工调控的有效途径,将离体穗或连体穗用茉莉酸甲酯(Methyljasmonate,MeJA)或水杨酸(Salicylic acid,SA)溶液浸穗,研究了MeJA与SA对光温敏雄性不育小麦BS366(Triticum aestivum L.)颖花开闭的诱导效应.结果表明,0.5、1.0、2.0、4.0 mmol/L MeJA均可显著诱导BS366离体穗开颖,并且诱导效应随浓度的增加而增强;1.0、2.0、4.0 mmol/L MeJA诱导的开颖率无显著差异,三者在处理后12 h内可诱导大部分的小花开颖,并且对低结实率的诱导效应更明显.适播(自交结实率为0%)的BS366对MeJA响应速度起初略快于晚播(自交结实率为7%),之后适播的BS366开颖率的增长呈先慢后快的变化,晚播的BS366则呈先快后慢的变化.4.0 mmol/L MeJA亦可显著诱导田间连体穗开颖,MeJA处理后第1 d和第5 d人工授粉的结实率达80.4%和91.3%,表明MeJA处理对雌蕊无副作用.5.0和10.0 mmol/L的SA对MeJA诱导离体麦穗开颖的效应有明显的抑制效应,而2.0 mmol/L的SA没有抑制效应;各浓度的SA均能显著促进经MeJA诱导开颖的小花闭颖,5.0和10.0 mmol/L SA的效应更为明显.     

Use of phytotoxic plant residues for selective weed control

Both fall- and spring-planted grasses were evaluated for weed-suppressing ability after desiccation by freezing, glyphosate or paraquat. Populations of Portulaca oleracea L. and Digitaria ischaemum (Schreb.) Muhl. were reduced by 70% and 98%, respectively, by residues of sorghum (Sorghum bicolor L.). Total weed biomass and weight of several indicator species were also consistently reduced with residues of barley (Hordeum vulgare L.), oats (Avena sativa L.), wheat (Triticum aestivum L.) and rye (Secale cereale L.), as well as the sorghums. In general, the larger-seeded vegetables, particularly legumes, grew normally or were sometimes stimulated by the cover-crop residues, whereas several species of smaller-seeded vegetables were severely injured. The use of Populus wood shavings as a control mulch allowed separation of physical and chemical aspects of the residues. Glasshouse experiments with two soils confirmed both weed-suppressing and crop-stimulating effects of sorghum residues. Water extracts of sorghum herbage were toxic to indicator species in sterile bioassays: this suggests that phytotoxins are directly released by the plant residues.     

小麦品种"中国春"主要过敏原CM16基因的克隆及序列分析

为了给小麦主要过敏原CM16蛋白的重组表达和免疫活性鉴定等研究奠定基础,通过生物信息学方法设计并合成简并性引物,利用RT-PCR技术对小麦主要过敏原CM16基因进行克隆,并进行序列分析. 结果表明,克隆获得了小麦主要过敏原CM16基因.基因开放阅读框为432个碱基(包括终止密码子), 编码143个氨基酸.该序列编码的蛋白相对分子质量约为15 782,等电点为5.17.序列同源性分析发现其与国外报道的已知小麦CM16基因具有很高的同源性(同源性为99%),因此认为其系小麦过敏原基因,在GenBank数据库中的登录号为EU883599.     

Control of volunteer cereals with post-emergence herbicides in maize (Zea mays L.)

Volunteer winter cereals are found sporadically in maize (Zea mays L.) fields across southern Ontario. Seven field trials were conducted over a two-year period (2006 and 2007) at four locations to determine the efficacy of five acetolactate synthase (ALS)-inhibiting herbicides for the control of volunteer cereals applied at two post-emergence application timings (2–4 and 4–7 maize leaf tips). The volunteer cereals were a hard red winter wheat (Triticum aestivum L.) (‘Hyland AC Morley’), soft red winter wheat (‘Pioneer 25R47’), soft white winter wheat (‘Pioneer 25W41’), and a autumn rye (Secale cereale L.) (‘FR’) cultivar. Volunteer cereal competition in maize resulted in a yield reduction of up to 44%. Foramsulfuron, nicosulfuron, nicosulfuron/rimsulfuron provided greater than 70% control of the volunteer cereals at 56 days after treatment (DAT), while primisulfuron and rimsulfuron provided greater than 60% control. Volunteer cereal control with early and late application was greater than 82 and 61%, respectively. Hard red winter wheat was the most sensitive to the ALS-inhibiting herbicides with control of 84–93%. Soft red and soft white winter wheat cultivars were intermediate in sensitivity with control of 76–87%, while autumn rye was the least sensitive with control of at 56–71% control at 56 DAT. Maize yields were improved when volunteer cereals were controlled with the use of herbicides compared to the weedy control, but were lower than the weed-free control. Early herbicide application resulted in improved control of volunteer cereals and higher maize yield.     

苋菜、小麦和玉米对铯的吸收和积累差异

苋菜、小麦和玉米用石英砂和Hoagland营养液进行盆栽培养,3叶期时,向培养液中添加不同浓度铯(0、0.5、1、5、10、20 mmol/L CsCI),在处理后第7、14、21、28天取样,分析3种植物对铯的吸收富集差异.结果表明:苋菜、小麦和玉米中铯含量均与处理浓度和时间呈显著正相关,在20 mmol/L铯浓度下处理28 d后达到最大值;苋菜对铯的富集能力和富集系数远远高于小麦和玉米,在处理浓度小于1 mmol/L时,小麦和玉米对铯的吸收富集无显著差异,但随着处理浓度的增加和处理时间的延长,小麦对铯的富集能力显著高于玉米;苋菜、小麦和玉米的根、茎、叶对铯的吸收富集也存在显著差异,苋菜叶片是主要的富集器官,富集量表现为叶、茎、根依次减小,而小麦和玉米的根是主要富集器官,富集量表现为根、茎、叶依次减小;铯显著抑制苋菜、小麦和玉米的生长发育,随着处理浓度的增加,生物量显著降低,根冠比显著增加.本研究结果表明苋菜是一种铯富集能力强的具有较高潜在应用价值的铯污染修复植物,而小麦和玉米是铯低富集植物.