Genetic diversity of the D-genome in <Emphasis Type="Italic">T. aestivum</Emphasis> and <Emphasis Type="Italic">Aegilops</Emphasis> species using SSR markers

Simple sequence repeats (SSRs), highly dispersed nucleotide sequences in genomes, were used for germplasm analysis and estimation of the genetic relationship of the D-genome among 52 accessions of T. aestivum (AABBDD), Ae. tauschii (D^tD^t), Ae. cylindrica (CCD^cD^c) and Ae. crassa (MMD^cr1D^cr1), collected from 13 different sites in Iran. A set of 21 microsatellite primers, from various locations on the seven D-genome chromosomes, revealed a high level of polymorphism. A total of 273 alleles were detected across all four species and the number of alleles per each microsatellite marker varied from 3 to 27. The highest genetic diversity occurred in Ae. tauschii followed by Ae. crassa, and the genetic distance was the smallest between Ae. tauschii and Ae. cylindrica. Data obtained in this study supports the view that genetic variability in the D-genome of hexaploid wheat is less than in Ae. tauschii. The highest number of unique alleles was observed within Ae. crassa accessions, indicating this species as a great potential source of novel genes for bread wheat improvement. Knowledge of genetic diversity in Aegilops species provides different levels of information which is important in the management of germplasm resources.     

偏凸-柱穗山羊草双二倍体与普通小麦杂种F1的细胞遗传学分析

[目的]研究偏凸-柱穗山羊草双二倍体与普通小麦杂种F1的染色体配对特点。[方法]利用压片法对普通小麦烟农15、SDAU18及其杂种F1的小孢子发生和花粉发育过程进行了细胞学观察。[结果]两亲本（烟农15和SDAU18）的小孢子发生和花粉发育基本正常,二者结实率也基本正常。F1小孢子发生过程紊乱,花粉母细胞减数分裂中期I出现较高频率的单价体和二价体,分别为10.11和18.29个,而多价体出现的频率非常低;减数分裂后期I,每个细胞落后染色体平均为5条;四分体期,每个四分体微核数平均为4.43个。在杂种F1花粉发育的每个时期都产生了不同频率的败育花粉,但败育主要发生在第1次孢子有丝分裂以后。在三细胞成熟花粉期,杂种F1可育花粉仅有31%。[结论]为深入分析和利用该双二倍体提供了细胞遗传学依据。     

偏凸-柱穗山羊草双二倍体与普通小麦杂种F_1的细胞遗传学分析

[目的]研究偏凸-柱穗山羊草双二倍体与普通小麦杂种F1的染色体配对特点。[方法]利用压片法对普通小麦烟农15、SDAU18及其杂种F1的小孢子发生和花粉发育过程进行了细胞学观察。[结果]两亲本（烟农15和SDAU18）的小孢子发生和花粉发育基本正常,二者结实率也基本正常。F1小孢子发生过程紊乱,花粉母细胞减数分裂中期I出现较高频率的单价体和二价体,分别为10.11和18.29个,而多价体出现的频率非常低;减数分裂后期I,每个细胞落后染色体平均为5条;四分体期,每个四分体微核数平均为4.43个。在杂种F1花粉发育的每个时期都产生了不同频率的败育花粉,但败育主要发生在第1次孢子有丝分裂以后。在三细胞成熟花粉期,杂种F1可育花粉仅有31%。[结论]为深入分析和利用该双二倍体提供了细胞遗传学依据。     

QTL Mapping for Important Agronomic Traits in Synthetic Hexaploid Wheat Derived from Aegiliops tauschii ssp. tauschii

Aegiliops tauschii is classified into two subspecies: Ae. tauschii ssp. tauschii and Ae. tauschii ssp. strangulata. Novel genetic variations exist in Ae. tauschii ssp. tauschii that can be utilized in wheat improvement. We synthesized a hexaploid wheat genotype (SHW-L1) by crossing an Ae. tauschii ssp. tauschii accession (AS60) with a tetraploid wheat genotype (AS2255). A population consisting of 171 F8 recombinant inbred lines was developed from SHW-L1 and Chuanmai 32 to identify QTLs associated with agronomic traits. A new genetic map with high density was constructed and used to detect the QTLs for heading date, kernel width, spike length, spikelet number, and thousand kernel weight. A total of 30 putative QTLs were identified for five investigated traits. Thirteen QTLs were located on D genomes of SHW-L1, six of them showed positive effect on agronomic traits. Chromosome region flanked by wPt-6133–wPt-8134 on 2D carried five environment-independent QTLs. Each QTL accounted for more than 10% phenotypic variance. These QTLs were highly consistent across environments and should be used in wheat breeding.     

普通小麦-卵穗山羊草种质的菲利普孢囊线虫抗性

菲利普孢囊线虫(Heterodera filipjevi)是我国黄淮麦区新发现的一种病原线虫,但在小麦属中缺乏有效抗源。为从小麦亲缘种属中发掘抗病资源,采用室内接种平均单株雌虫鉴定法,从34份卵穗山羊草(Aegilops geniculataRoth)材料中筛选出6份抗H. filipjevi的种质材料,其中PI542187表现高抗,PI564186、PI573396、PI374365、PI361880和PI374365表现抗病。对中国春–卵穗山羊草染色体附加系抗性鉴定发现,卵穗山羊草7U^g和5M^g附加系的单株白雌虫数明显低于中国春。连续两年又对17份小麦?卵穗山羊草5M^g-5D易位系材料的抗性鉴定发现,5M^g464、5M^g466和5M^g457抗性较好。     

1BL/1RS小麦的分子和细胞学鉴定及黏类CMS育性恢复区域分布的分析

【目的】揭示黏类小麦细胞质雄性不育系育性恢复基因的区域分布及恢复材料的1BL/1RS情况,为黏类细胞质雄性不育系优良恢复源筛选提供理论依据,以推动黏类小麦雄性不育"三系"强优势组合的选配能不断得到新的材料保障。【方法】以8个黏类不育系和国内外一批小麦品种(系)为试材,结合分子和细胞学技术,进行1BL/1RS易位系鉴定,并利用中国国内法对其育性恢复程度进行分类。【结果】在参试的256份材料中,初步鉴定约20%的小麦品种(系)属于1BL/1RS易位系;育性表现半不育、高可育和全可育的品种(系)分别有86.15%、91.67%和100%为非1BL/1RS易位系,表现全不育和高不育的品种(系)中均有40%左右属于1BL/1RS易位系;恢复能力在50%以上的品种(系)在中国春麦区、长江中下游冬麦区、西南冬麦区和华南冬麦区的比例依次为60%、65.85%、68.42%和71.43%。【结论】黏类不育系优良恢复源大都为非1BL/1RS易位系,主要集中在中国春麦区和南方冬麦区。     

麦田恶性杂草节节麦发芽特性研究

为深入了解节节麦的发芽特性,从种子吸水、萌发温度以及播种深度等方面对节节麦和小麦进行了对比研究。结果表明,节节麦与小麦种子吸水进程均可分为3个时期,即快速吸水期、缓慢吸水期和吸水停滞期。小麦吸水主要集中在前期,而节节麦吸水分散于前、中期;在整个吸水过程中,无论是吸水量还是吸水率,小麦普遍高于节节麦。温度对节节麦和小麦发芽率的影响也具有较大差异,在5~25 ℃范围内,节节麦发芽率随着温度的升高而提高,不同温度间具有显著差异;而小麦在不同温度条件下发芽率保持一致,不受影响。在大田条件下,节节麦的出苗率受播种深度影响较大,随播种深度的增加出苗率显著降低,二者呈极显著负相关。     

小麦－山羊草复合群的起源与与进化研究进展

摘要： 为了给小麦-山羊草复合群的研究和利用提供依据,本文详细综述了多倍体小麦和多倍体山羊草的起源与进化过程,及山羊草在多倍体小麦起源中的作用,总结了在小麦-山羊草复合群起源及进化研究方面存在的问题,并对现存问题的解决提出了展望。     

Starch characterisation and variability in GBSS loci of synthetic hexaploid wheats and their durum and <Emphasis Type="Italic">Aegilops tauschii</Emphasis> parents

Greater variability in starch properties is found in lower ploidy wheats than in commercial hexaploid wheats. This paper reports on the starch properties and variability in granule bound starch synthase (GBSS) loci of 17 diploid (Aegilops tauschii) and 12 tetraploid (durums) potential progenitors of wheat, compared with 29 synthetic hexaploid wheats produced from such progenitors. Starch properties examined were granule size distribution, swelling power, amylose content, gelatinisation and amylose-lipid dissociation properties. A PCR screening method was able to detect the presence or absence of each of the three GBSS genes. It also detected polymorphisms in eight diploids and nine hexaploids, all displaying the same 25 bases deletion in the D genome allele of GBSS. Two tetraploids and five hexaploids were null 4A for GBSS. There was little difference in the amylose contents and amylose-lipid dissociation peak temperatures of the synthetic hexaploids and the lower ploidy wheats. The synthetic hexaploids showed intermediate swelling power values with the durums giving the highest swelling powers. The durums also had higher B granule contents than the A. tauschii accessions, but not as high as the synthetics. However, the A. tauschii samples gave the highest gelatinisation peak temperatures. The presence of the null 4A mutation was positively correlated with swelling power, amylose content and DSC measurements. The new smaller D genome allele of GBSS was associated with slightly higher swelling power. These results confirm the value of wheat progenitor lines as sources of new starch properties for hexaploid wheat. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Expression of morphological and flowering time variation through allopolyploidization: an empirical study with 27 wheat synthetics and their parental Aegilops tauschii accessions

It was recently shown that allopolyploidy brings novel epistatic interactions to genes belonging to different genomes. However, systematic studies of the phenotypic relationships between synthetic hexaploid wheats and their parental lines have not been conducted. In this study, 27 synthetic hexaploid wheats were produced by crossing the tetraploid wheat cultivar ‘Langdon’ with 27 accessions of Aegilops tauschii. Variations in 20 morphological and flowering traits were analysed in both the synthetic wheat lines and the parental Ae. tauschii accessions. The 20 traits exhibited large variations in the wheat lines. For many of the traits, the degree of variation in the parental accessions was reduced in the hexaploid derivatives. Principal component analysis of floret‐related traits divided the Ae. tauschii accessions into two subspecies, ssp. tauschii and ssp. strangulata, but this parental pattern of subspecific division was not detectable in the hexaploids. Our results suggest that the ‘Langdon’ genome may have an alleviating effect on the expression of D‐genome‐derived variations in derived synthetics.