高直链淀粉玉米amylose-extender基因功能标记的开发及应用

直链淀粉的含量是玉米淀粉品质的重要指标,受隐性核基因amylose-extender(ae)控制.生产中直链淀粉含量的测定费时、费力,因此高直链淀粉玉米的改良需要寻找快速、简便、准确的基因检测方法.本实验对高直链淀粉玉米材料和普通玉米材料ae基因的cDNA进行了测序,结果显示高直链淀粉材料cDNA 序列第9外显子(84...     

粳稻直链淀粉含量选择对杂种后代品质和产量性状及遗传多样性的影响

本研究选用4个稻米直链淀粉含量有显著差异的粳稻品种配制2个杂交组合,研究其粳稻籽粒直链淀粉含量选择对杂种后代品质和产量性状及遗传多样性的影响。结果表明,连续定向选择籽粒直链淀粉含量对杂种后代蒸煮食味品质和产量性状产生不同程度的影响,在蒸煮食味品质性状中下降粘度值、粘滞峰消减值、食味值,在产量性状中单株粒重、单株穗数、每穗粒数所受的影响较大,直链淀粉含量降低到13%以下时,稻米蛋白质含量和食味值及淀粉谱特性均发生明显的变化,而且直链淀粉含量过低将导致每穗粒数和单株粒重的显著下降;直链淀粉含量高的后代株系遗传背景基本来自于高直链淀粉含量亲本,反之直链淀粉含量低的后代株系遗传背景基本来自于低直链淀粉含量亲本,直链淀粉含量的连续定向选择使后代的遗传背景趋于双亲之一。     

寒地稻米直链淀粉含量与植株农艺性状 的相关性及灰色关联分析

对水稻植株农艺性状与稻米直链淀粉含量之间的关系进行了研究，结果表明：除千粒重和分蘖数与直链淀粉含量呈负相关外，其余各性状与其都呈正相关。与直链淀粉含量关联度较大的性状主要是株高、单株产量、粒长、剑叶面积和穗颈弯曲度等。     

杂交水稻主要米质性状的配合力分析——Ⅰ.直链淀粉含量

选取杂交水稻4个不育系和9个恢复系按不完全双列杂交配组得到36个杂交组合,测定了108个小区(3次重复)稻米的直链淀粉含量,旨在分析杂交水稻亲本直链淀粉含量的一般配合力(gca)和组合的特殊配合力(sca),以期为优质杂交稻米亲本选育和组合选配提供一定的参考依据。结果表明:对F_1稻米直链淀粉含量的影响,亲本间和组合间均存在显著或极显著差异。亲本不育系珍汕97A和恢复系明恢63的gca最好,而sca最好的是汕优63。gca低(高)的两亲本,其F_1稻米的直链淀粉含量一般也低(高)。但由于亲本间存在相互作用,这一现象并不存在于所有组合。在优质杂交稻米亲本选育和组合选配过程中,既要注意亲本(特别是恢复系)本身的特性和一般配合力效应,也要考虑组合的特殊配合力效应。     

直链淀粉含量偏低型杂交粳稻组合的稻米品质评价

随着稻米产量的增长和人们生活水平的提高,对稻米品质的要求也与日俱增。淀粉是稻米最主要的成分,稻米中淀粉含量超过糙米的90%,此外直链淀粉含量是影响稻米品质的主要因素。研究如何提高稻米品质也已成为育种学家关注的热点和所面临的重要问题之一。利用5个直链淀粉含量偏低型水稻恢复系材料与粳型不育系2701A配组得到的组合,研究水稻组合间直链淀粉含量和稻米品质间的差异,为低直链淀粉杂交水稻的选育、恢复系的筛选以及优质食味杂交水稻育种提供一定的理论基础与种质资源。     

高粱籽粒直链淀粉和支链淀粉含量的基因效应分析

1990和1991年以Hayman4×4完全双列杂交方法对高粱籽粒直链淀粉含量和支链淀粉含量的基因效应进行了研究。结果表明,直链淀粉和支链淀粉含量的遗传符合加性-显性模型。基因的加性效应和显性效应对两个品质性状均有重要作用,但相对而言前者较后者更重要,属部分显性。直链淀粉含量基因的显性方向指向增效,支链淀粉含量基因的显性方向指向减效。亲本中与两性状有关的隐性基因频率高于显性基因的频率。两性状的狭义遗传力均较高。 亲本高杆牛心红和小粘白高粱含显性基因较少,认为此两品种是提高支链淀粉含量育种的优良亲本材料。     

利用正义RNAi技术提高玉米直链淀粉含量效果的研究

为了研究利用正义RNAi技术提高玉米直链淀粉含量效果,用基因枪法将构建的sbeⅡb正义RNAi表达载体pBAC506和pBAC508(筛选标记基因分别为35S启动子及Adh1-intron1增强驱动的epsps和bar)导入玉米(Zea mays)自交系幼胚愈伤组织,经过筛选、分化和再生获得了44株转基因当代植株,经PCR扩增、PCR-Southern检测有30株为阳性.选择9株健壮的阳性植株进行基因组Southern-blotting分析,结果表明7株T0植株整合了目的基因,其中4株整合了1个转基因拷贝,2株整合了2个转基因拷贝,1株整合了3个转基因拷贝.这7株中有2株结实,直链淀粉含量分别为23.22%和24.60%,有一定的小幅提高.下一步要进行较大规模的基因枪转化,得到比较大的转基因群体,以对更多转基因后代进行鉴定,期望筛选出外源基因多拷贝插入和直链淀粉含量大幅提高的株系.     

利用Wx基因分子标记辅助选择技术培育中等直链淀粉含量的恢复系

为培育中等直链淀粉含量的水稻恢复系,以HC086为供体亲本(其Wx基因来自美国水稻品种Francis),以优良的水稻恢复系R898、R476、R838、R6547为受体亲本,利用PCR-AccI分子标记检测技术在回交世代进行辅助选择,将供体材料控制直链淀粉的Wx基因导入到不同恢复系中。对后代株系的基因型及其直链淀粉含量的分析结果表明,直链淀粉含量普遍有了显著提高,受体亲本的直链淀粉含量由10.6-14.4%提高到了18.0-21.4%。改良株系与广占63S和Y58S的配组实验表明,F1代杂交种的直链淀粉含量较原组合有显著提高,并达到适中直链淀粉含量水平,且主要农艺性状没有发生显著改变。说明分子标记辅助选择是改良水稻品种直链淀粉含量的快速有效的方法。     

高直链淀粉玉米胚性愈伤组织的诱导、继代、植株再生的研究

以不同类型的高直链淀粉玉米自交系为试验材料 ,用不同类型的培养基对其幼胚进行诱导,结果发现不同类型的高直链淀粉玉米均可诱导出愈伤组织 ,诱导率的高低主要取决于基因型、培养基种类、激素浓度等。本实验针对不同基因型玉米,摸索出能够诱导出II型愈伤组织的适宜条件,确定最佳的培养基 ,并能进行长期继代保存。同时通过不同激素的配比,有两个材料分化出苗     

利用MAS技术改良香稻‘R15’的直链淀粉含量

R15是适应性较广,产量较高的中熟晚籼香稻品系,但由于含有Wx^a基因,其直链淀粉含量高达23.5%,严重影响食用口感。因此,我们以含有Wx^b等位基因的不育系Y58S为供体,通过杂交、回交,利用RAD测序技术、分子标记辅助筛选等技术,经过8个世代的筛选,成功用Wx^b基因替换掉R15中的Wx^a基因,培育出1个新的纯合株系——‘深华R16’,其染色体上有10882234 bp长度的碱基,基因型和供体亲本‘Y58S’一致,占2.92%;有362363285 bp长度的DNA片段基因型和受体亲本‘R15’一致,占97.08%;其直链淀粉含量为14%。将‘Y58S’分别与‘深华R16’和‘R15’进行组配,结果表明,‘Y58S’/‘深华R16’组合的直链淀粉含量(13.9%)低于‘Y58S’/‘R15’组合的直链淀粉含量(19.9%),其它米质性状与农艺性状基本一致。本研究为分子标记辅助育种提供了新思路,培育出一新的水稻品系。     

粳型杂种稻米品质性状的表现及遗传控制

研究了由4个不育系及其保持系与7个恢复系配组的24个粳型杂种的9个品质性状的遗传表现 , 结果表明： (1)杂种粳米的品质性状表现普遍介于双亲之间, 但粒宽和直链淀粉含量有 较多的超高亲组合, 糙米率和精米率有较多的超低亲组合。 (2)杂种的整精米率、 粒长、 粒宽、 垩白率、 糊化温度5个性状与不育系呈显著正相关; 糙米     

Genetic diversity of Tainan-white maize inbred lines and prediction of single cross hybrid performance using RAPD markers

To evaluate the genetic diversity of 13 maize inbred lines, and to determine the correlation between genetic distance and single cross hybrid performance, we employed the randomly amplified polymorphic DNA(RAPD)- a PCR-based technique. Six of these lines came from the Taichung population, and others derived from seven different sites. Forty different primers were used to give a total of 646 reproducible amplification products, 547 (84.7%) of them being polymorphic. Genetic divergence was determined using Jaccard's similarity coefficient, and a final dendrogram was constructed by UPGMA (unweighted pair-group method with arithmetical averages) cluster analysis in the CLUSTER procedure of the SAS system. The RAPD analysis was a useful tool in determining the extent of genetic diversity among Tainan-white maize inbred lines in the present case. Cluster analysis showed that the 13 inbred lines could be classified into distinct heterotic groups. There was no significant linear regression of grain dry weight heterosis value and mean performance of hybrids on genetic distance. And their coefficients of determination(R²) are small, so that predictive value is limited. The present results showed that the Jaccard's similarity coefficients based on RAPD data cannot be used to precisely predict the F₁ hybrids yield performance and heterosis value. This revised version was published online in August 2006 with corrections to the Cover Date.     

Relationship between hybrid performance and AFLP based genetic distance in highland maize inbred lines

The objectives of this study were to determine the crossing performance of highland maize inbred lines for grain yield, days to silk and plant height; estimate genetic distance (GD) among the inbred lines and in association with tester parents, and to investigate the relationship of GD with hybrid performance and midparent heterosis (MPH). A total of 26 inbred lines were crossed with six (population and line) testers in a factorial-mating scheme. The F_1’s and the parents were evaluated at five locations in Ethiopia. Nine amplified fragment length polymorphism (AFLP) primer pairs were used to genotype all the parents. The F_1’s were found to vary widely for grain yield and other traits measured. Yield superiority of more than 30% over the best hybrid check was obtained for some testcross hybrids. Midparent heterosis on average was moderate for grain yield and, plant height. And for days to silking, MPH values were mostly negative. Mean GD values determined from the inbred lines by population tester (0.680) and line tester (0.661) combinations were not significantly different. Cluster analysis separated the tester parents from the corresponding inbred lines. AFLP grouping of the inbred lines was in agreement with their pedigree records. Genetic distances derived from the inbred lines × all testers and from the population testers’ sub-group were not positively correlated with hybrid performance and MPH for most traits. In contrast, correlations of GDs involving the line testers’ sub-group with F_1’s and MPH were significantly positive but with low magnitude to be of predictive value.     

Genetic diversity of oilseed Brassica napus inbred lines based on sequence-related amplified polymorphism and its relation to hybrid performance

Significant heterosis for seed yield in oilseed rape has created interest in the development of hybrid cultivars. The DNA‐based marker protocol, sequence‐related amplified polymorphism (SRAP) was used to determine genetic diversity among oilseed rape maintainer and restorer lines. This measure was used in an attempt to establish an association between genetic distance and heterosis in hybrids for various agronomic traits. A total of 118 polymorphic loci were generated by 18 SRAP primer combinations. Based on the polymorphism generated by the markers, calculated similarity index values ranged from 0.46 to 0.97. Cluster analysis grouped 10 maintainer and 12 restorer lines into three groups, with the exception of two maintainer lines, PM5 and PM9, which fell outside these groups. The grouping of the lines was largely in agreement with the available pedigree data on their origin and agronomic performance. Analysis of variance among inbred lines and their resulting F₁ hybrids over two locations revealed significant differences for plant height, days to maturity and seed yield, but not for oil content. Substantial mid‐parent heterosis was observed only for seed yield, and ranged from 26% to 169%. All hybrids surpassed their respective inbred lines for this trait, except for a single cross combination of related lines. In general, crosses of lines located in different clusters yielded more than those from the same clusters. Regression analysis revealed a statistically significant relationship between the genetic distance of the parents and seed yield in their hybrid, and their derived mid‐parent and high‐parent heterosis. The correlation coefficient between genetic distance and yield (0.64) indicated a moderately strong relationship, so it is possible that some of the SRAP markers might be linked to quantitative trait loci for seed yield.     

Construction of chromosomal segment substitution lines and genetic dissection of introgressed segments associated with yield determination in the parents of a super‐hybrid rice

Heterosis is a phenomenon whereby hybrids of inbred lines produce favourable phenotypes that exceed those of their parents. Traits of interest are higher yield and stronger stress tolerance. The two‐line super‐hybrid rice ‘Liangyoupei9’ (LYP9) shows superiority to both its elite inbred line ‘93‐11’ and ‘Pei'ai64s’ (‘PA64s’) parents and conventional hybrids. However, the genetic basis of its hybrid vigour, especially yield determination, remains elusive. In the present study, a set of 156 chromosome segment substitution lines (CSSLs) carrying overlapping segments from ‘PA64s’ in a genetic background of ‘93‐11’ were constructed and planted in six environments. Three major agronomic traits, viz. panicle length (PL), heading date (HD) and plant height (PH), and five yield‐related traits, viz. grain weight per panicle (GWP), number of grains per panicle (GPP), 1000‐grain weight (TGW), seed set (SS) and number of panicles of per plant (PPP), were evaluated over 3 years. Quantitative trait loci (QTL) analysis was conducted using a likelihood ratio test based on stepwise regression. Forty‐six putative QTL distributed on 11 chromosomes were detected in more than one year. Remarkably, GWP of four CSSLs carrying positive yield QTL outperformed the recurrent parent ‘93‐11’ by more than 15%, in at least two environments. These results indicate that CSSLs are effective in identifying yield‐associated traits, and lines harbouring such QTL will be rich in resources for future molecular breeding programmes.     

Hybrid performance and AFLP- based genetic similarity in faba bean

Successful prediction of heterosis and performance of F₁-hybrids from the genetic similarity of their parents based on molecular markers has been reported in several crops and can be very helpful in hybrid breeding. The relationship between genetic similarities based on amplified fragment length polymorphism (AFLP) of 18 European faba bean lines and their hybrid performance and heterosis was investigated. Parental lines, 62 F₁-hybrids and their F₂-progenies were evaluated in field trials in four environments in Germany for seed yield, 1,000-seed weight and plant height. Results clearly demonstrated a stable superiority of the hybrids over their inbred parents and elite check cultivars, and showed a marked and varying amount of heterosis. Parental seed yield and F₂-hybrid yield were promising as predictors for F₁-hybrids. AFLP analysis of the 18 inbred lines using 26 EcoRI/MseI primer combinations resulted in 1202 polymorphic fragments. Cluster analysis based on genetic similarity estimates unambiguously identified pedigree-related inbred lines. No clear separation of the 18 inbred lines into subgroups was detected. Correlation coefficients between genetic similarity estimates and either heterosis or F₁-hybrid performance were small and not useful. Also correlations between specific genetic similarity and specific combining ability were too small for all traits to be of predictive value. Results showed that AFLP-based genetic similarities are not useful to predict the performance of hybrids or heterosis within the elite European faba bean gene pool.     

Higher grain yield and higher grain protein deviation underline the potential of hybrid wheat for a sustainable agriculture

Grain yield and protein content are traits of major importance in wheat breeding, but their combination is challenging due to a tight negative correlation. Protein yield and grain protein deviation have been proposed as selection criteria to simultaneously improve both traits. Sedimentation volume is an indicator of protein quality, which plays an important role for bread‐making quality in wheat. All these traits have been investigated in our study with 135 parental inbred lines, their 1,604 hybrids and 10 commercial check varieties evaluated at five environments. The focus of our study was to investigate the usefulness of the grain protein deviation and to define a bivariate model for calculating the grain protein deviation. Further, we compared line and hybrid wheat for grain yield and quality‐related parameters such as protein content and sedimentation volume. The grain protein deviation determined with a bivariate model delivered robust estimates of variance components and enabled a balanced selection of genotypes with improved protein content and grain yield across different quality classes. Although heterosis for protein content and sedimentation volume was negative, hybrids had a higher grain protein deviation as well as higher grain yield at a given sedimentation volume or a given protein content than line varieties.     

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.     

家系间数量性状主基因效应的分析

具有主基因差异的纯系杂交，其后代家系按主基因型表现为不同类型。本文以似然函数法分析Ｆ３家系资料，提出家系主基因型鉴别，主微基因效应和互作以有主基因显性度的估计和测试方法。应用于籼稻株高和直链淀粉含量两组资料的分析，结果表明，家系间的分离比均符合一对主基因的理论比。两对主基因的增值基因均表现不完全显性，高杆基因对半矮杆基因的显性度估计为０．６７，高直链淀粉含量基因对低直链淀粉含量基因估计为０．３２。     

Genetic Variation for Maize Epicuticular Wax Response to Drought Stress at Flowering

Drought stress is thought to promote epicuticular wax accumulation on maize leaves, which reduces plant water loss. We evaluated 62 maize inbred lines and their hybrid testcross progeny for epicuticular wax accumulation on flag leaves at flowering under full and limited irrigation regimes. Extracted wax was measured as a percentage of wax weight to leaf weight (WLW) and leaf area (WLA). Eleven genotypes had above average WLW as both inbred lines and hybrid testcrosses. Thirteen genotypes had above average WLA as either inbred lines or hybrid testcrosses. The drought treatment did not significantly alter WLW or WLA. Heritability of WLW was 0.17 (inbred lines) and 0.58 (hybrid testcrosses). Heritability of WLA was 0.41 (inbred lines) and 0.59 (hybrid testcrosses), suggesting it is a better trait than WLW for epicuticular wax screening. Correlations (r) between inbred lines and their testcross progeny were 0.44 and 0.18, for WLW and WLA, respectively. Heritability of grain weight per ear and plot yield was highest in hybrid testcrosses, with no correlation between inbred and hybrid germplasm. It is not warranted to evaluate epicuticular wax accumulation as the sole drought tolerance mechanism. However, it may be a good secondary trait to observe in relation to grain yield production in hybrids tested under water‐limiting conditions.