对生玉米籽粒品质性状的杂种优势和配合力分析

本文利用对生基因转育获得的对生与互生自交系及其杂交组合,研究了对生性状对玉米主要品质性状的杂种优势和配合力的遗传效应的影响。结果表明:对生自交系籽粒品质性状的配合力效应一般高于互生玉米,在蛋白质含量上,对生F1杂种优势与普通互生F1无明显差异,而在油份和淀粉含量上对生F1较互生表现出明显的优势。不同组配方式对F1对生群体籽粒品质性状的杂种优势存在差异,在对生组合利用中通过互×互组配较对×对组配能使F1获得更高的蛋白质含量;选育含油量较高的对生系,利用对×对组合有助于选育高油杂交种;选育淀粉含量较高的含有不同对生基因的互生自交系作亲本,利用互×互组配有助于选育高淀粉对生杂交组合。     

对生玉米产量性状的杂种优势和配合力分析

本文利用对生基因转育获得的对生与互生自交系及其杂交组合,研究了对生性状对产量性状杂种优势和配合力的遗传效应的影响。结果表明:对生玉米同互生玉米一样具有普遍的杂种优势,在产量性状上F1对生株优势互×互组合大于对×对组合和对×互(互×对)组合;对生性状的转育对产量性状的一般配合力有降低效应,而含有对生基因的互生玉米具有较高的一般配合力效应,因此,在对生玉米育种中可以利用含有不同对生基因的互生自交系作亲本来组配杂交组合(互×互),从而获得较高的制种产量和高产的对生杂交种。     

玉米对生性状的遗传选择和组配效果的研究

通过F4代的26个转育的对生自交系进行对生性状的连续10代定向选择,以及三种不同的组配方式(对生×互生、对生×对生、互生×互生)对对生率影响的研究,结果表明:连续定向选择是获得稳定对生系的一条有效的技术途径,对生性状在不同的遗传背景下,其定向选择的进程和效率是不同的。不同的组配方式,对于选育F1全对生植株组合的效果是不同的,从F1对生率来看,对生×对生>对生×互生>互生×互生;从F1优势来看,互生×互生>对生×互生>对生×对生。     

对生玉米和互生玉米染色体核型比较研究

本文利用对生性状转育获得的六组对生和互生姊妹系,通过风油精法染色体制片,首次研究了对生玉米与互生玉米的染色体核型差异。结果表明：对生玉米的染色体含有2对随体,而互生玉米却只有1对。对生玉米和互生玉米共有的一对随体分布在第6对染色体短臂上,对生玉米额外一对随体主要位于第10对染色体短臂上。     

玉米自交系秸秆品质性状鉴定与评价

利用近红外漫反射光谱法,对50份常用普通玉米自交系和50份高油自交系秸秆的中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、可溶性糖(WSC)和粗蛋白(CP)4个品质性状进行了鉴定评价和相关性分析。结果表明,各品质性状变异较大,各性状自交系间差异均达极显著水平。不同品质性状变异程度不同,其中WSC含量变异最大,变异系数达34.23%。WSC与NDF、ADF极显著负相关,NDF与ADF含量极显著正相关。高油系表现为高WSC、CP和低NDF、ADF含量,总体上高油系秸秆品质优于普通玉米。     

利用单酶切cDNA—AFLP技术分离玉米对生性状相关基因差异表达片段

为了深入地研究对生玉米这一珍贵的高产育种种质资源和植物形态发育突变材料形成的分子机理和调控机制,通过构建合适的玉米对生、互生近等基因系总RNA池,首次采用改进的单酶切cDNA-AFLP技术,对扩增的玉米对生性状相关基因的差异表达片段进行筛选、分离和生物信息学分析.结果共获得29条差异表达片段:对生玉米增强表达23条、抑制表达6条.选取其中5条(STT-TT、STT-TC、STT-CC、STT-GC、SCT-TG)增强表达片段进行克隆和测序,序列同源性分析表明:STT-GC与烟草细胞色素b5基因有80%的同源性、SCT-TC与玉米、牛筋草、大麦、狗尾草、水稻等的α-微管蛋白基因有90%以上的同源性.实验证明:单酶切cDNA-AFLP技术是一种研究玉米基因差异表达的实用方法.     

转基因玉米HGK60在不同遗传背景下抗虫性鉴定及农艺性状分析

为研究转基因玉米HGK60在不同遗传背景下遗传稳定性和抗虫效果,利用转Bt cry1Ah基因的转基因玉米HGK60为供体,通过回交转育的方式将cry1Ah基因分别导入玉米自交系郑58、昌7-2、lx05-4、lx03-2,获得转基因玉米自交系HGK60-郑58、HGK60-昌7-2、HGK60-lx03-2、HGK60-lx05-4,并杂交获得HGK60-郑单958（HGK60-郑58 × HGK60-昌7-2）和HGK60-鲁单9066（HGK60-lx05-4 × HGK60-lx03-2）,转化体特异性PCR证明cry1Ah基因已转入不同遗传背景玉米中,ELISA检测不同遗传背景转基因玉米叶片中Cry1Ah蛋白表达情况,结果表明在不同遗传背景玉米自交系和杂交种中Cry1Ah蛋白表达没有显著差异;田间人工接虫和室内玉米螟抗虫性鉴定结果表明,不同遗传背景的转基因玉米高抗玉米螟,室内接虫后4 d幼虫死亡率达到100%;对不同遗传背景转基因玉米HGK60进行农艺性状分析,结果显示与受体对照玉米相比,两者之间农艺性状没有显著差异,转基因玉米HGK60可用于抗虫玉米品种的选育。     

粳稻穗角与谷粒性状的相关性及谷粒性状遗传分析

粳稻穗角小的品种产量高而品质差。谷粒性状与产量和品质都有关联。为培育产量与品质相协调的品种提供相关遗传信息, 测定了粳稻直立穗品种丙8979和弯曲穗品种C堡及其重组自交系349个株系的穗角和7个谷粒性状, 分析了穗角与谷粒性状之间的相关性, 并运用主基因+多基因混合遗传模型, 对7个谷粒性状进行了遗传分析。结果表明, 穗角与粒厚、长厚比和宽厚比均无显著相关, 而与千粒重、粒长、粒宽和长宽比均呈极显著正相关。7个谷粒性状均受2对主基因+多基因控制, 2对主基因的作用方式因性状而异。千粒重、粒长、长厚比和宽厚比4个性状以主基因遗传为主; 粒宽、粒厚和长宽比3个性状以多基因遗传为主。     

粳稻穗角与谷粒性状的相关性及谷粒性状遗传分析

粳稻穗角小的品种产量高而品质差。谷粒性状与产量和品质都有关联。为培育产量与品质相协调的品种提供相关遗传信息,测定了粳稻直立穗品种丙8979和弯曲穗品种C堡及其重组自交系349个株系的穗角和7个谷粒性状,分析了穗角与谷粒性状之间的相关性,并运用主基因+多基因混合遗传模型,对7个谷粒性状进行了遗传分析。结果表明,穗角与粒厚、长厚比和宽厚比均无显著相关,而与千粒重、粒长、粒宽和长宽比均呈极显著正相关。7个谷粒性状均受2对主基因+多基因控制,2对主基因的作用方式因性状而异。千粒重、粒长、长厚比和宽厚比4个性状以主基因遗传为主;粒宽、粒厚和长宽比3个性状以多基因遗传为主。     

导入八氢番茄红素合酶和番茄红素β-环化酶基因的玉米后代性状分析

以分别转有枸杞八氢番茄红素合成酶基因Lmpsy和枸杞番茄红素β-环化酶基因Lmlycb的两种转基因的天塔五号自交系玉米植株为转基因材料,以非转基因的天塔五号自交系为对照组,对它们的光合速率,类胡萝卜素含量,植株性状,产量相关指标及生物量进行了调查和统计学分析。结果表明将类胡萝卜素代谢途径关键酶的基因导入天塔五号自交系植株,能提高植株类胡萝卜素的表达量,消除光污染,提高光合速率,增加光合产物的积累量。     

Reduced representation sequencing: a success in maize and a promise for other plant genomes

Plant, and particularly cereal genomes, are challenging to sequence due to their large size and high repetitive DNA content. Gene-enrichment strategies are alternative or complementary approaches to complete genome sequencing that yield, rapidly and inexpensively, useful sequence data from large and complex genomes. The maize genome is large (2.7 Gbp) and contains large amounts of conserved repetitive elements. Furthermore, the high allelic diversity found between maize inbred lines may necessitate sequencing several inbred lines in order to recover the maize "gene pool". Two gene-enrichment approaches, methylation filtration (MF) and high C(o)t (HC) sequencing have been tested in maize and their ability to sample the gene space has been examined. Combined with other genomic sequencing strategies, gene-enriched genomic sequencing is a practical way to examine the maize gene pool, to order and orient the genic sequences on the genome, and to enable investigation of gene content of other complex plant genomes.     

Analysis of genetic diversity and relationships among waxy maize inbred lines in Korea using SSR markers

Information regarding the genetic diversity and genetic relationships among elite inbred lines is necessary to improve new cultivars in maize breeding programs. In this study, genetic diversity and genetic relationships were investigated among 84 waxy maize inbred lines using 50 SSR markers. A total of 269 alleles were identified at all the loci with an average of 5.38 and a range between 2 and 13 alleles per locus. The gene diversity values varied from 0.383 to 0.923 with an average of 0.641. The cluster tree generated using the described SSR markers recognized two major groups at 32% genetic similarity. Group I included 33 inbred lines while group II included 51 inbred lines. The clustering patterns of most of the waxy maize inbred lines did not clearly agree with their source, pedigree or geographic location. The average GS among all inbred lines was 35.7 ± 10.8. Analysis of waxy maize inbred lines collected from Korea and China at 50 SSR loci revealed higher values of average number of alleles (4.9) and gene diversity (0.638) in Korean inbred lines as compared to Chinese inbred lines (3.5 and 0.563, respectively). The information obtained from the present studies would be very useful for maize breeding programs in Korea.     

Grouping of tropical mid-altitude maize inbred lines on the basis of yield data and molecular markers

The classification of maize inbred lines into heterotic groups is an important undertaking in hybrid breeding. The objectives of our research were to: (1) separate selected tropical mid-altitude maize inbred lines into heterotic groups based on grain yield data; (2) assess the genetic relationships among these inbred lines using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers; (3) examine the consistency between yield-based and marker-based groupings of the inbred lines. Thirty-eight tropical mid-altitude maize inbred lines were crossed to two inbred line testers representing the flint and dent heterotic pattern, respectively. The resulting testcrosses were evaluated in a trial at three locations for 2 years. Significant general combining ability (GCA) and specific combining ability (SCA) effects for grain yield were detected among the inbred lines. The tester inbred lines classified 23 of the 38 tested inbred lines into two heterotic groups based on SCA effects and testcross mean grain yields. This grouping was not related to endosperm type of the inbred lines. The outstanding performance of testcrosses of the remaining 15 inbred lines indicates the presence of significant genetic diversity that may allow the assignment of the lines into more than two heterotic groups. Diversity analysis of the 40 maize inbred lines using AFLP and SSR markers found high levels of genetic diversity among these lines and subdivided them into two main groups with subdivision into sub-groups consistent with breeding history, origin and parentage of the lines. However, heterotic groups formed using yield-based combining ability were different from the groups established on the basis of molecular markers. Considering the diversity of the genetic backgrounds of the mid-altitude inbred lines, the marker-based grouping may serve as the basis to design and carry out combining ability studies in the field to establish clearly defined heterotic groups with a greater genetic similarity within groups.Communicated by H.H. Geiger     

玉米自交系间遗传距离与产量杂种优势,杂种产量的关系

以13个玉米自交系及其按双列杂交配制的78个单交种为材料,研究性状选择、亲本选择对遗传距离与产量杂种优势、杂种产量关系的影响,结果表明:(1)当性状数较少时,遗传距离与产量杂种优势、杂种产量的关系因性状的不同而异;当性状数较多时,遗传距离与产量杂种优势、杂种产量的关系为抛物线,受性状影响较小;(2)当所选亲本材料的遗传差异较大时,遗传距离与产量杂种优势的关系为抛物线;当所选亲本材料的遗传差异较小时,遗传距离与产量杂种优势的关系为直线或不相关。     

南斯拉夫玉米自交系改良我国优良杂交种的遗传潜势研究

以9个引进南斯拉夫玉米自交系为母本、11个分属于不同优势类群的8个优良杂交种的亲本自交系为父本,组配107个杂交组合,采用Dudley方法分析了利用南斯拉夫自交系改良我国优良杂交种产量的遗传潜势、利用方法及改良的主要穗粒性状。结果表明,引进自交系具有较高的间接利用价值,9801、9802、9803、9805、9807、9808、9809可以分别通过改良不同亲本自交系的不同穗粒性状提高各杂交种的产量水平。具体改良效果还有待通过进一步的育种实践予以印证。     

Evaluating Tripsacum‐introgressed maize germplasm after infestation with western corn rootworms (Coleoptera: Chrysomelidae)

Maize (Zea mays L.) is a valuable commodity throughout the world, but corn rootworms (Chrysomelidae: Diabrotica spp.) often cause economic damage and increase production costs. Current rootworm management strategies have limitations, and in order to create viable management alternatives, researchers have been developing novel maize lines using Eastern gamagrass (Tripsacum dactyloides L.) germplasm, a wild relative of maize that is resistant to rootworms. Ten maize Tripsacum‐introgressed inbred lines derived from recurrent selection of crosses with gamagrass and teosinte (Zea diploperennis Iltis) recombinants and two public inbred lines were assessed for susceptibility to western corn rootworm (Diabrotica virgifera virgifera LeConte) and yield in a two‐year field study. Two experimental maize inbred lines, SDG11 and SDG20, had mean root damage ratings that were significantly lower than the susceptible public line B73. Two other experimental maize inbred lines, SDG12 and SDG6, appeared tolerant to rootworm damage because they exhibited yield increases after rootworm infestation in both years. In the majority of cases, mean yield per plant of experimental maize lines used in yield analyses was equal to or exceeded that of the public inbred lines B73 and W64A. Our study indicates that there is potential to use Tripsacum‐introgressed maize germplasm in breeding programs to enhance plant resistance and/or tolerance to corn rootworms, although further research on insect resistance and agronomic potential of this germplasm needs to be conducted in F₁ hybrids.     

The feasibility of producing inbred rather than F1 hybrid cultivars in Brussels sprouts: predictions from early generations

Predicting the performance of recombinant inbred lines derived by single seed descent (SSD) following crosses between inbred lines is most reliable for traits in which epistasis and genotype environment interaction are absent. The analysis of two field trials of Brussels sprouts indicated the presence of such effects in seven quantitative characters. These effects could be minimised by transforming the scale on which each character was measured. Predictions were made of the likely performance of the recombinant inbred lines currently being produced by SSD at the Institute of Horticultural Research, Wellesbourne, compared with that of current F₁ hybrid varieties. The predictions from the first trial of F₂ material were encouraging for harvest date, stem length and waste weight, but low for sprout number, quality, marketable yield and total yield. Predictions from F₃ material in the second trial were good for sprout number and total yield (in addition to harvest date, stem length and waste weight as before), but still low for marketable yield and quality, with less than 0 01% of lines expected to perform better than the F₁. Model fitting to variances suggested the presence of linkage disequilibrium in dispersion for waste weight, but no information could be obtained about linkage disequilibrium for the two most important characters, marketable yield and quality. The broad heritability of each character except stem length was lower than 0 5 (0 3 or lower for total yield, waste weight and quality), suggesting that advanced generation selection, as used in SSD, might be more successful than selection in the early generations.     

Molecular marker-based genetic diversity assessment of Striga-resistant maize inbred lines

Striga-resistant maize inbred lines are of interest to maize breeding programs in the savannas of Africa where the parasitic weed is endemic and causes severe yield losses in tropical maize. Assessment of the genetic diversity of such inbred lines is useful for their systematic and efficient use in a breeding program. Diversity analysis of 41 Striga-resistant maize inbred lines was conducted using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers to examine the genetic relationships among these lines and to determine the level of genetic diversity that exists within and between their source populations. The two marker systems generated 262 and 101 polymorphic fragments, respectively. Genetic similarity (GS) values among all possible pairs of inbred lines varied from 0.45 to 0.95, with a mean of 0.61±0.002 for AFLPs, and from 0.21 to 0.92, with a mean of 0.48±0.003, for SSRs. The inbred lines from each source population exhibited a broad range of GS values with the two types of markers. Both AFLPs and SSRs revealed similar levels of within population genetic variation for all source populations. Cluster and principal component analysis of GS estimates with the two markers revealed clear differentiation of the Striga-resistant inbred lines into groups according to their source populations. There was clear separation between early- and late-maturing Striga-resistant inbred lines. Considering the paucity of germplasm with good levels of resistance to Striga in maize, the broad genetic diversity detected within and among source populations demonstrates the genetic potential that exists to improve maize for resistance to Striga.     

中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的关系研究

在玉米单交种育种中 ,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以 1 7个优良玉米自交系为亲本 ,按照双列杂交配组合 ,利用 RAPD技术分析了 1 7个自交系的多态性以及 RAPD标记与 9个重要农艺性状 (包括产量 )的关系。基于 RAPD标记计算的相似系数聚类将 1 7个自交系分为 5个类群 ,经分析与系谱亲缘关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的 ,与聚类前比较 ,聚类后平均遗传距离与平均产量、平均特殊配合力的相关系数显著提高 ,类间平均产量高于类内平均产量。RAPD技术可揭示优良玉米自交系的系谱亲缘关系 ,将自交系划分成不同的类群 ,从而为选择类间自交系杂交 ,进行亲本选配和分子标记辅助育种提供一种方法。