玉米单交种不同收获时问对其种子萌发过程中保护酶活性的影响

以玉米单交种郑单958为试验材料,研究了不同收获时间对种子发芽率,以及种子萌发过程中保护酶活性和丙二醛含量的影响.结果表明,授粉后40d收获的玉米种子其发芽率最低,未达到国家玉米良种发芽率85%的标准;授粉后45～60d收获的玉米种子其发芽率为89.7%～97.3%.均高于国家标准,其中,55d收获的玉米种子其发芽率最高.随着玉米收获期的推迟,玉米种子在萌发过程中,SOD、CAT和POD活性均呈上升趋势,而MDA含量呈下降变化.授粉后50d、55d和60d收获的种子萌发过程中SOD、CAT和POD活性都显著高于40d、45d收获的单交种,而其MDA含量都显著低于40d、45d收获的单交种.研究表明玉米单交种的最佳收获时间为授粉后55d.     

Seedling Peroxidase and IAA Oxidase Activities in Relation to Hybrid Vigour in Pearl Millet (Pennisetum americanum L. Leeke)

Seedlings of three hybrids and their parental lines were analyzed for growth, and peroxidase as well as IAA oxidase activities in cytoplasmic and salt-extracted ionically bound fractions with a view to evaluate heterosis in pearl millet. The hybrid vigour was manifested in roots and shoots of all the three hybrids clearly for growth and activities of peroxidase and IAA oxidase except the wall-bound IAA oxidase. Either better parental or mid-parental heterosis was discernible. The role of peroxidase and IAA oxidase systems in meristematic activity and removal of excessive auxin levels to bring about maximal growth response in the hybrids is discussed.     

玉米杂交种及其亲本自交系的生化指纹鉴定

本试验以浙单9号等五个玉米杂交组合及其亲本自交系为材料,进行种子盐溶蛋白聚丙烯酰胺凝胶电泳等多种电泳鉴定方法的研究,以揭示玉米杂交种及其亲本自交系的“生化指纹”(biochenucal fingerprint),以及筛选出适合于玉米杂交种及其亲本自交系真实性和纯度鉴定的方法。结果表明,各供试玉米杂交种及其亲本自交系都具有相应的、唯一的种子盐溶蛋白聚丙烯酰胺凝胶电泳所显现的生化指纹。对于有些组合。玉米芽鞘和叶片绿色组织过氧化物酶同工酶电泳图谱存在阴极第4、第5酶带差异,因这两条酶带的差异稳定,并且重现性好,故能用过氧化物酶同工酶技术对其进行有效地鉴定。上述两种方法,尤其是前者,因技术要求不高,费用低,快速及重现性好等特点,能满足我国目前种子检验室日常玉米品种纯度快速测定工作的要求,具育良好的应用前景。     

外源SO2对紫苏种子萌发的影响

为了研究外源SO2对紫苏种子萌发及其幼苗生理生化的影响,用不同浓度的SO2（0,0.5,1,1.5,2,2.5 mmol/L）处理紫苏种子,使其在适当的条件下萌发,测定其种子的发芽率、发芽势及发芽指数,以及幼苗叶绿素、丙二醛（MDA）、过氧化物酶（POD）、多酚氧化酶（PPO）及可溶性糖含量。结果表明,随着SO2浓度的升高,发芽率、发芽势、发芽指数、POD活性和可溶性糖含量都呈先上升后下降的趋势,在1.5 mmol/L时达到最大;叶绿素含量随着SO2浓度的升高,呈逐渐上升的趋势;MDA含量、PPO活性则随着SO2浓度的升高,呈先下降后上升的趋势,在1.5 mmol/L时到达最低。实验表明用1.5 mmol/L浓度的外源SO2处理紫苏种子有利于其萌发和生长,可以提高幼苗的抗氧化胁迫能力。     

Changes in the Functional Components and Radical Scavenging Activity of Korean Maize Hybrids According to Different Cropping Seasons

We evaluated the proximate composition, free sugar content, fatty acid composition, carotenoid content, total phenol content, and radical scavenging activity of the grain from various Korean maize hybrid cultivars grown in two different cropping seasons. The moisture, crude ash, crude fat, crude protein, total starch, and amylose contents were significantly higher in most of the maize hybrid cultivars when grown in the early-season than when grown in the late-season. The free sugar content, fatty acid composition, carotenoid content, and total phenol content differed significantly between cultivars and cropping seasons. The highest unsaturated fatty acid compositions of maize hybrids of early-season and late-season were 86.05 and 86.29%, respectively, in the Daanok cultivar. The carotenoid contents were significantly higher in maize hybrids of late-season compared to those of early-season. The highest total phenol content was 108.09 mg/100 g in Singwangok of the late-season. The radical scavenging activity of maize hybrids differed significantly between cultivars and cropping seasons.     

甘蓝型油菜品系一些酶的活性与抗菌核病的关系

以6个抗病品种（系）M004、湘油15号、中R-888、中R-783、084、085和二个感病品种（系）98C04、甘油5号为材料,研究接种菌核病菌前后叶片中过氧化物酶（PO）、多酚氧化酶（PPO）、苯丙氨酸解氨酶（PAL）、超氧物歧化酶（SOD）的活性变化。结果表明：接种前,PO、PAL二种酶活性与油菜品种抗病性相关不显著,而PPO、SOD酶活性     

Best linear unbiased prediction of triticale hybrid performance

Predicting single-cross performance is of special interest in hybrid breeding of triticale. We used molecular and phenotypic data of factorial triticale crosses and compared several approaches to predict their single-cross performance. Twenty-three inbred lines and their 76 incomplete factorial crosses were field evaluated for grain yield, plant height, and heading time at five locations in Central Europe. In addition, the parental lines were genotyped with 52 SSR markers. Plant height and heading time were predicted with high accuracy based on mid-parent performance. In contrast, prediction of hybrid performance based on mid-parent value was not accurate for grain yield. Using general combining ability effects led to an enhanced prediction accuracy of hybrid grain yield performance. This accuracy could be slightly improved using best linear unbiased prediction approaches. The prediction accuracy was considerably high even if the number of tested hybrids was small. Consequently, best linear unbiased prediction of hybrid performance is a promising tool for hybrid triticale breeding programs.     

弱光胁迫对不同基因型玉米雌雄花发育和授粉结实能力的影响

以不耐阴型玉米豫玉22和耐阴型玉米郑单958为试验材料,设置自然光照和弱光胁迫两个处理,研究弱光胁迫对不同基因型玉米雌雄花发育的影响。研究结果表明,弱光胁迫延缓了雌雄穗的生长发育,表现为抽雄、吐丝和盛花期延迟,花期和雌雄间隔期延长。弱光胁迫下,在吐丝期不耐阴型玉米花粉量比对照显著增加,耐阴型玉米花粉量与对照差异较小;不耐阴型玉米花粉表面网纹在弱光胁迫下变粗且间隙增大,花粉萌发孔及其附近严重畸形,有的明显内陷,花粉内淀粉粒数目显著减少,营养供应能力减弱,耐阴型玉米在弱光胁迫下花粉表面网纹略有加粗或没有变化,萌发孔略微凹陷且程度远低于不耐阴型玉米,花粉中淀粉粒密度略有降低。遮光处理后,不耐阴型玉米的花粉活力、花粉萌发率和萌发速率表现为下降,而耐阴型玉米表现为上升。花丝的生长速率及伸出苞叶数量在弱光胁迫下显著下降,果穗上部花丝受到的影响最大,向下逐渐减弱。弱光胁迫下两个基因型玉米穗长和穗粒数减少,不耐阴型玉米受弱光胁迫影响的程度高于耐阴型玉米。雌雄间隔期延长、营养供应能力减弱导致的花粉畸形、花丝生长速率和可授粉花丝数目的减少以及籽粒IAA含量的下降和ABA含量的增加是弱光条件下玉米穗粒数显著减少的主要原因。     

利用清蛋白多态性鉴定玉米种子纯度研究

利用改进的聚丙烯酰胺凝胶电泳技术,对生产上应用的53个玉米杂交种及亲本自交系干种子清蛋白(白蛋白Albumin)进行了电泳分析。结果表明,改进的聚丙烯酰胺凝胶电泳技术分辨率高、鉴别能力强、准确;不仅能鉴别杂交种及亲本自交系,对血缘关系较近的材料,如同母异父单交种、含有同一血缘的不同衍生系也能区分开。利用该技术     

Maize commercial hybrids compared to improved population hybrids for grain yield and agronomic performance

Improved maize (Zea mays L.) populations and population hybrids can both be profitable alternatives to commercial single-cross hybrids as well as good elite sources of diverse inbred lines. The objective of this research was to compare grain yield and agronomic performance between early maturing maize population hybrids and current early maturing commercial single-cross hybrids. This is a consequence of our research program targeted at identifying alternative heterotic patterns for the northern Corn Belt. Improved maize populations and population hybrids (S₀ generations) were evaluated in experiments arranged in randomized complete block and partially balanced lattice designs across 29 environments. Grain yield potential of population hybrids was optimally expressed under irrigated conditions. Data across environments showed that 20% of the population hybrids evaluated were not different (P 0.05) from at least one of the commercial single-cross hybrids for grain yield performance, root lodging, and stalk lodging percentages. The average mid-parent heterosis value across population hybrids from different geographic regions was 20.4% with negative estimates observed in only two population hybrids. Breeding efforts toward elite populations and population hybrids have demonstrated that germplasm improvement is extremely valuable and deserves public funding. These efforts should be supported in order to enable the development of elite sources of diverse inbred lines and the development of improved population hybrids for specific markets (e.g., organic) to increase producer options. Public maize breeding programs utilizing recurrent selection methods for germplasm improvement could address the need. These programs, however, should incorporate extensive testing of population hybrids.     

Hybrid breeding for biomass yield in winter triticale: II. Combining ability and hybrid prediction

Accurate hybrid prediction and knowledge about the relative contribution of general (GCA) and specific combining ability (SCA) are of utmost importance for efficient hybrid breeding. We therefore evaluated 91 triticale single-cross hybrids in field trials at seven environments for plant height, heading time, fresh biomass, dry matter content and dry biomass. Fresh and dry biomass showed the highest proportion (23%) of variance due to SCA. Prediction accuracies based on GCA were slightly higher than based on mid-parent values. Utilizing parental kinship information yielded the highest prediction accuracies when both parental lines have been tested in other hybrid combinations, but still moderate-to-low prediction accuracies for two untested parents. Thus, hybrid prediction for biomass traits in triticale is currently promising based on mid-parent values as emphasized by our simulation study, but can be expected to shift to GCA-based prediction with an increasing importance of GCA due to selection in hybrid breeding. Moreover, the performance of potential hybrids between newly developed lines can be predicted with moderate accuracy using genomic relationship information.     

一氧化氮对双孢蘑菇采后生理及贮藏品质的影响

以硝普钠（SNP）为一氧化氮供体,研究了不同浓度NO在常温（25±1℃）和低温（4±1℃）条件下对双孢蘑菇‘F56’贮藏过程中相关品质（失重率、开伞率、可溶性固形物、维生素C（Vc）、游离氨基酸含量）以及过氧化氢酶（CAT）、过氧化物酶（POD）和多酚氧化酶（PPO）活性的影响。结果表明,0.09 mmol/L SNP释放的NO显著抑制了双孢蘑菇采后失重率和游离氨基酸含量的上升,减缓了可溶性固形物含量的增加、延缓Vc的降解,抑制了开伞率的增大;使CAT、POD的活性显著增强,同时降低PPO活性。因此,0.09mmol/L SNP处理显著提高了常温和低温下双胞蘑菇‘F56’ 贮藏期间的CAT、POD活性,抑制了PPO活性的升高,延缓了菇体品质的下降。     

利用SSR技术快速准确鉴定杂交玉米种子纯度

利用一种快速、廉价的DNA提取方法,提取了两个玉米杂交种及其亲本的DNA用于SSR分子标记分析。分析结果显示,10对被分析的引物中有4对在两个杂交种双亲之间显示出多态性,可以用于相应的杂交种纯度分析。另外,分别利用同工酶技术和SSR分子标记技术同时分析了来自这两个杂交种的种子样品的纯度,分析发现,对于一个杂交种,两种方法都能可以鉴定,并且两者检测的结果是一致的,但是对于另外一个杂交种,由于其父母本非常接近,同工酶不能将其区分。因此,这些结果显示SSR分子标记技术可以很好地用于杂交玉米种子的纯度鉴定,即使是这个杂交种是来自两个非常接近的自交系的。     

Combining ability amongst CIMMYT’s early maturing maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) germplasm under stress and non-stress conditions and identification of testers

CIMMYT (International Maize and Wheat Research Institute) Zimbabwe’s early maturing maize program, which aims to supply seed to approximately 4 million hectares of maize area in eastern and southern Africa, lacks adequate information on heterotic relationships among early maturing germplasm and has no early maturing testers for hybrid development. Open-pollinated varieties (OPVs) and hybrids are the products targeted for this region. Among the hybrids, three-way and double-cross hybrids are desired. Thus the use of single crosses as testers would be an appropriate choice for such a breeding program as one could potentially identify three-way combinations during the early generation test. A twelve-parent diallel was formed and crosses evaluated to identify heterotic groups and single-cross testers. Crosses were evaluated under four different environments in Zimbabwe, two optimal, one low nitrogen stress and one drought stress. P5 (an early maturing line from heterotic group A) and CML 395 (a late maturing inbred line from heterotic group B) were used as reference parents to establish heterotic groupings of germplasm used in the diallel. The single cross (P7/P8) was identified as a potential group A tester because of: (a) co-classification of inbred lines into heterotic group A, (b) good yields-9.8 t/ha (optimal), 3.4 t/ha (low nitrogen) and 2.1 t/ha (drought); and (c) good GCA effects for grain yield (0.49 t/ha) of line P7 while line P8 contributed to reduced height and anthesis-silking interval.     

Grain yield and root characteristics of summer maize (Zea mays L.) under shade stress conditions

Low light is a major adversity affecting yield and quality of summer maize in the Huang‐Huai‐Hai region of China. We conducted a field experiment to explore the effects of shading on root development and yield formation in two summer maize hybrids (Zea mays L.), Denghai605 (DH605) and Zhengdan958 (ZD958). The experiment consisted of four treatments (CK: ambient sunlight, S1: shading from tasselling to physiological maturity stage, S2: shading from six‐leaf to tasselling stage, S3: shading from seeding to physiological maturity stage). Shading had a strong impact on the development of roots in the upper soil layer. Shading significantly decreased the root dry weight, root/shoot ratio, root length density, root absorption area and active absorption area. The results showed that treatments in a diminishing sequence of effects on root from S3, S1, S2 to CK. Overall, shading decreased the root morphologic and activity indices, and decreased yield in summer maize. During an average of 2 years, yields of ZD958 in S3, S2 and S1 decreased by 85%, 24% and 55%, yields of DH605 in S3, S2 and S1 decreased by 87%, 26% and 67%, in compare to CK. The results will be useful for hybrid selection and improving cultural practices for enhancing the maize shading resistance in Huang‐Huai‐Hai region.     

不同灌水施氮方式对玉米叶片生理特性和产量的影响

为了研究不同灌水施氮方式对玉米叶片生理特性、产量及其构成的影响。以春玉米‘宜单629’为供试材料,监测不同灌水方式下玉米生育期内的叶面积指数(LAI)、生理特性指标和籽粒产量。结果表明,与均匀灌水均匀施氮(CICN)相比,交替灌水均匀施氮(AICN)和交替灌水交替施氮水氮协同供应(AIANS)显著提高玉米抽雄期及以后第7、14、21、28和35天的LAI和叶绿素含量及抽雄期、灌浆期和乳熟期叶片的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性、可溶性蛋白含量、玉米行数、行粒数、穗粒数、千粒质量和籽粒产量(P<0.05),但显著降低相应生育期叶片的MDA、可溶性糖和脯氨酸含量(P<0.05)。可见,AICN和AIANS有利于提高玉米的LAI和抗氧化酶活性,改善活性氧产生与清除之间的关系,从而使玉米产量增加。     

Resistance gene deployment strategies in cereal hybrids using marker-assisted selection: Gene pyramiding, three-way hybrids, and synthetic parent populations

Marker-assisted selection (MAS) for resistance genes (R-genes), identified using molecular markers and quantitative trait loci (QTL) analysis, is now possible in many crops. MAS can be used to pyramid several R-genes into a single host genotype. However, this may not provide durable genetic resistance because the pathogen is exposed to a full homozygous pyramid during hybrid seed production and to a full heterozygous pyramid in the resultant hybrid. Alternative gene deployment strategies that generate genetic variability were analysed, for hybrid cereal cultivars of pearl millet, maize, sorghum and rice, using maintainer lines (B-lines) with two smaller complementary pyramids. An F₁ seed parent, produced on two such B-lines, can be used to produce a three-way hybrid. All target loci are heterozygous for resistance alleles in the F₁ seed parent, and the pathogen is exposed in the hybrid to a host population that is heterogeneous and heterozygous for alleles at the resistance loci targeted by MAS. Alternatively, single-cross hybrids can be made on seed parents that are maintained by two B-lines that differ for the complementary resistance gene pyramids. In a cross-pollinated crop, the B-lines are allowed to intermate to produce a synthetic B-line. In an inbreeding crop, the B-lines are equivalent to a two-component multiline variety. In inbreeding crops, because there is no intermating between the B-line components, the resultant synthetic seed parents have a higher frequency of genotypes with resistance alleles (R-alleles) at several resistance loci. However, in both cross-pollinated and inbreeding crops the genotypic structure in the hybrids is almost the same. All alternatives to a single-cross hybrid having a full pyramid produce hybrid cultivars having lower frequencies of resistance alleles. The frequency of genotypes having R-alleles at several loci increases greatly in both seed parent and hybrid when the overall frequency of R-alleles in the maintainer lines increases. This is simply done by adding a maintainer line that has a full pyramid or by the component lines having overlapping pyramids. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular identification of Pm12-carrying introgression lines in wheat using genomic and EST-SSR markers

The traditional process of obtaining maize hybrids involves the generation of inbred lines through successive generations of selfing and subsequent testcrosses in order to identify the best combining ability by allelic complementation. A fast alternative to obtain inbred lines is to induce the formation of haploids followed by chromosome doubling. However, even with the aid of haploid-inducing genetic sources, this strategy has not been widely used in maize breeding programs, partly due to difficulties inherent to haploid generation and identification. In order to evaluate the possibility of using dihaploids to generate homozygous maize tropical lines, we used the androgenetic haploid inducer line W23 as a female parent in crosses with the tropical single-cross hybrid BRS1010. Within the progeny of these crosses, 462 seeds were phenotypically selected as putative haploids by the purple-colored endosperm and colorless embryo conditioned by the R1-nj gene. Among these, only four individuals were confirmed as being haploids using SSR markers, chromosome counting and flow cytometry, showing that the phenotypic marker was not efficient in detecting haploids in the tropical maize genotype used. All four haploids as well as some diploid plants presented reduced size, corroborating the difficulties for haploid identification by phenotypic evaluation. Genetic diversity analysis revealed by SSR markers divided the haploids in two groups represented by flint and dent maize inbred lines, which could be helpful in identifying complementary dihaploid lines. The present article demonstrates that a combination of haploid production and SSR fingerprinting is a feasible strategy for maize hybrid development in tropical germplasm.     

玉米与矮花叶病毒互作对防御反应酶系活性的影响

选取抗、感甘蔗花叶病毒-玉米矮化株系的玉米自交系黄早四和Mo 17,与国内流行的甘蔗花叶病毒-玉米矮化B株系组成的非亲合性和亲合性互作体系为研究对象,以未接种为对照,对两类互作类型的防御反应酶系中的苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)、过氧化氢酶(CAT)和超氧化物岐化酶(SOD)活性变化规律进行系统研究.非亲合性互作中PAL活性始终高于对照,整个互作过程中形成两个较大的峰,亲合性互作中除96 h高于对照外,其它时间均比对照低;非亲合性互作中POD活性先升后降,形成1个明显的峰值,亲合性互作中POD活性与对照相比没有明显变化,144 h形成1个明显酶活高峰;非亲合性互作体系中多元酚氧化酶除24 h外,酶活性均高于对照,形成1个酶活高峰,亲合性互作中酶活与对照相比没有较大变化;非亲合性互作中CAT活性始终低于对照,亲合性互作中在接种24～120 h内形成两个酶活高峰均高于对照;非亲合性互作中SOD活性先降后升,72 h达到酶活高峰,亲合性互作中变化趋势与非亲合性互作相似,酶活高峰出现在120 h.     

不同植物生长调节剂对烤烟生长发育的影响

为深入了解植物生长调节剂对烤烟生长发育的影响,以云烟87为试验材料,采用大田试验的方法,研究微生物菌剂、生根粉和表油菜素内酯对烤烟农艺性状、抗氧化酶、多酚氧化酶、根系活力以及烤后烟叶化学成分的影响。结果表明,施用植物生长调节剂对烟株农艺性状、根系活力、过氧化指标相关酶类和烟叶化学成分均有影响。随着烟株的生长,各处理过氧化物酶（POD）活性逐渐升高,多酚氧化酶（PPO）活性呈现降-升-降的趋势。与对照和施用表油菜素内酯相比,施用微生物菌剂灌根和生根粉浸根提高了烤烟的株高、茎围、最大叶长、最大叶宽和有效叶片数;在移栽后45d提高了POD和PPO活性,增强了根系活力,使烤后烟叶化学成分更加协调。综合来看,施用微生物菌剂灌根和生根粉浸根能够改善烤烟的生长发育情况,提高烟叶品质。