花期玉米(Zea mays)穗三叶叶形结构的遗传效应及配合力分析

为了剖析玉米叶形结构的遗传规律,进而拓宽优良株型自交系的遗传基础。本研究以12份不同叶形结构玉米自交系组配的32份F1杂交种为试材,在2个生态环境下,花期采用加性-显性-母体遗传模型(ADM)对其穗三叶叶长、叶宽、叶夹角、叶向值及叶面积进行遗传效应和配合力分析。结果表明:(1)玉米穗三叶叶长、叶宽及叶向值主要受基因的加性效应调控,其次是显性效应,同时还兼受加性×环境互作效应或母体×环境互作效应等遗传体系的调控,育种改良中宜在早代对其进行选择;叶夹角主要受基因的母体效应调控,其次是加性效应,另外还受加性×环境互作效应及母体×环境互作效应影响,育种中宜选择叶夹角较小的材料作为母本进行改良;叶面积只受基因的显性效应及显性×环境互作效应的调控,其应从较晚世代中进行遗传选择。(2)除父本叶长的一般配合力差异不显著外,父本其余性状的一般配合力和母本全部性状的一般配合力间差异均显著或极显著,且这5个叶形相关性状的全部特殊配合力间差异极显著。(3)从相应自交系各性状的一般配合力相对效应值分析发现,‘锋1999马’和‘锋1913硬’的综合性状表现优良,有利于组配出叶片大小适中及株型紧凑的优良耐密高产F1杂交组合。研究结果表明,玉米穗三叶5个叶形结构的遗传效应不尽相同,相应亲本5个叶形结构的一般配合和特殊配合力间存在明显差异,因此在玉米叶形结构遗传改良上应按照相应性状的遗传特征选择对应改良策略进行改良,并根据综合性状表现优良的亲本有目的地组配杂交组合,提高玉米理想株型育种效率。本研究为进一步剖析玉米叶形结构的遗传机理及玉米理想株型育种提供参考。     

抗双链RNA依赖性蛋白激酶PKR基因表达载体构建及在玉米中的遗传转化

玉米病毒性病害和杂草严重影响其产量和品质。以pCAMBIA5300为基础载体,应用In-Fusion克隆技术构建了双价植物表达载体pCAMBIA5300-Ubi-PKR-CaMV35S-EPSPS,其中含有抗双链RNA依赖性蛋白激酶PKR基因和磷酸烯醇式丙酮酸莽草酸-3-磷酸合酶EPSPS基因,分别由玉米泛素Ubi启动子和花椰菜花叶病毒35 S启动子启动。以玉米种子黄化苗的茎尖分生组织为受体,用农杆菌介导法进行遗传转化,将抗双链RNA依赖性蛋白激酶基因PKR和抗除草剂草甘膦基因EPSPS导入玉米自交系掖478中,获得转基因植株及其子代。     

玉米耐低钾特性的遗传效应分析

利用数量遗传学方法,在低钾土壤上研究耐低钾基因型玉米植株茎秆长度性状和苗期叶片耐性指数的遗传模型及其关系。结果表明：耐低钾基因改变了植株高度、穗上茎长和穗位高度的各遗传效应;在所有遗传效应中,降低玉米耐性的遗传效应占主导地位;玉米耐低钾特性受主效基因和微效基因控制;主效基因是由增强耐性和降低耐性的两种基因类型构成,其互作增加玉米耐性,微效基因及其互作降低耐性。     

Genetic location and evaluation of chromosomal segments for drought tolerance at flowering stage in maize using selected backcross populations

Development and evaluation of introgression lines have become one of the promising approaches to understanding genetic mechanisms of important traits in crops. In this study, three sets of drought tolerance (DT) selected backcross populations in maize, including two BC₂S₁ populations and one BC₃S₁ population, from a cross of Qi319 and Huangzaosi (recurrent parent) were developed by selecting for short anthesis-silking interval (ASI) under the condition of serious water stress at flowering stage. The introgression of chromosome segments was identified using microsatellite markers. The results showed that the marker allele introgression frequencies in the three DT populations significantly increased compared with the expected value under no selection. There was a notable increase of introgression frequency for the most of these markers which were located on all chromosomes except chromosome 8, but most concentrated on some chromosomes, especially on chromosomes 4 and 5. For example, chromosome 4 harboured the largest number of introgression regions, on which five segments were detected. The ASI in the DT populations significantly shortened compared with the initial BC₂ population.     

Identification of quantitative trait loci for drought tolerance at seedling stage by screening a large number of introgression lines in maize

The maize genome hosts tremendous phenotypic and molecular diversity. Introgression lines (ILs), developed by continuous backcrossing to recurrent parents, could provide a unique genetic stock for quantitative trait locus (QTL) mapping. Using maize lines from six heterotic groups of different ecological zones, we developed >500 BC₂F₂ IL sets by crossing 11 inbred lines (as recurrent parents) with >200 local maize inbred lines (as donor parents). Of them, 34 IL sets were selected as a subset for drought tolerance screening and a total of 417 ILs survived under severe water stress at seedling stage. One set of 32 surviving ILs, derived from Chang7-2/DHuang212, was used for QTL mapping with simple sequence repeat markers covering the whole genome, with seven QTL detected. Furthermore, investigating all surviving ILs, we identified two common regions in bin 3.04, corresponding to marker intervals bnlg1904–umc1772 and umc1223–bnlg1957, respectively, which shared high genetic variation in three IL sets. Our results indicated that selective genotyping can be used to identify genetic loci for complex traits. The ILs, highly selected for drought tolerance in this study, provide a unique set of materials for both genomic studies and development of enhanced germplasm resources.     

玉米叶片保绿度开花后衰减特性与产量性状相关性初步研究

摘要：采用Excel工作表及Origin7.0、DPS统计分析软件对不同基因型玉米开花后叶片保绿度衰减特性与产量性状相关性进行了初步研究,结果表明：叶片保绿度最大衰减速率出现时间、最大衰减速率对产量性状影响大于叶片保绿度衰减启动时间对产量性状影响,最大衰减速率出现时间越晚、最大衰减速率越低,越有利于获得较高的单穗粒重、百粒重、穗粒数、容重、出籽率。     

Influence of delayed emergence and canopy skips on the growth and development of maize plants: a plant scale approach with CERES-Maize

Our objective was to study by observation and simulation the effects of (1) three different dates of seedling emergence and (2) presence of short sequences of missing plants in rows of maize canopies which we refer to as skips. Trials were carried out in Belgium and France during two consecutive years. We had eight trials in total (i.e. two experimental designs in two locations for 2 years). In a field mechanically sown with a precision drill to give ‘normal plants’, ‘late 1 plants’ and ‘late 2 plants’ (respectively) were sown by hand when ‘normal plants’ had germinated or emerged. The radiation available at the top of the plants was measured for each cohort which allowed the calculation of a ‘coefficient of correction for light climate’ corresponding to the ratio of incident light at the top of each cohort relative to normal. Heterogeneity (skips) was created in maize canopies by removing three adjacent plants situated in the same row at 16 different locations across the field. The part of the canopy affected by the presence of these skips was considered to consist of the 12 plants bordering each skip. Radiation was measured near soil level on both sides of these plants: plants of the part of the canopy affected by skips received on average the same amount of radiation as a uniform stand with a population density equal to three quarters of the density of the parts of the stand without skips. To test if differences in radiation reaching the level of plants in each cohort could explain the effects on the plants the behaviour of each cohort of plants in each location x year was modelled separately with CERES-Maize after introducing into the model a ‘coefficient of correction for light climate’ corresponding to each cohort×location×year combination. Simulations generally reproduced correctly decreases in LAI, total biomass, grain number and total grain yield in the late 1 and late 2 cohorts, but not decrease in individual grain weight. The observed loss of grain yield per unit surface area in the parts of the canopy disturbed by skips was between 7 and 15%, whereas corresponding simulated values were between 6 and 11%. In the absence of compensation, values in the disturbed parts would have been 20%. Thus in our conditions amount of light reaching the different cohorts explained a large part of the treatments effects.     

黑龙港流域玉米不同生育阶段气象因子对产量性状的影响

明确玉米生长发育不同阶段气象因子与产量的关系,有助于确定区域最适播期。通过调整播期来改变玉米生育期内气候条件,对于抵御阶段性不良气象因子的胁迫并最终实现高产目标有重要意义。本研究以郑单958为试验材料,于2009年至2010年在黑龙港地区中国农业大学吴桥试验站进行分期播种试验,分析产量及产量构成因素与不同阶段气象因子的关系。结果显示: (1)由于年际间气象条件的差异,产量及其构成因素并非简单地随播期变化而变化。(2)在试验设定的高密度条件下,产量提升主要受千粒重的制约,穗粒数次之。(3)产量性状与不同生育阶段的多个气象因子显著相关。穗期、抽雄吐丝阶段的光照条件对穗粒数以及产量有影响;苗期、营养生长阶段气温日较差与产量显著正相关;抽雄吐丝前后的温度条件影响穗粒数;生育期总降水量影响穗粒数和千粒重的提升。该地区在调整播种时间、改进栽培措施时,上述关系应是考虑的重点。生产中可适当早播晚收,选用适宜的中晚熟品种,既可避开生育前期及籽粒形成阶段不利气象因子的影响,又可延长籽粒灌浆时间,充分利用该地区生育后期丰富的光热资源。     

Effect of dosage at the soft starch (h) locus on starch granule volume in maize

Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. Of the numerous endosperm carbohydrate mutants, the soft starch (h) mutant appears to have the greatest influence on starch particle volume. The objective of this study was to determine the gene dosage effect upon starch particle volume at the h locus. Two inbreds, B37 and Oh43, were studied in 1992 and 1993, and their hybrid B37 × Oh43 was studied in 1993. Appropriate crosses were made to establish four endosperm genotypes ++/+, ++/h, hh/+ and hh/h. Starch was extracted from mature kernels collected for each endosperm genotype and analysed for particle volume. The source of variation attributable to fitting two straight regression lines on number of h alleles was highly significant (P < 0.01) in all experiments, resulting in a horizontal‐line relationship among the three normal genotypes (++/+,++/h and hh/+) at 14.452 μm³3 and a regression line of slope 1.622 μm³ passing from hh+ to hh/h. There is no dosage effect of starch particle volume at the h locus; complete recessiveness of the h allele for starch particle volume is the same as the visual phenotypic observation of soft starch.     

Genetic variation of the rate of leaf appearance in maize: Possible yield prediction at the early stage

Summary Evidence of genetic variation for early vigour is presented using maize line × tester crosses. The leaf appearance rate and associated variance components are affected by a physiological stress attributable to the transition to autotrophic nutrition by the plant. At this stage, specific combining ability plays an important role in the total genetic variation. It is concluded that differing genetic controls exist in early and late material, and that this difference is also manifested in leaf initiation and elongation rates. The ground coverage rate, as a component of plant development, is genetically correlated to total dry matter yield. The genetic correlations vary according to the growth stage.