The agronomic performance of wheat doubled haploid lines derived from wheat x maize crosses

Summary The agronomic performance of 9 doubled haploid (DH) lines of Chinese Spring, 6 DH lines of Hope, 14 DH lines of the single chromosome substitution line Chinese Spring (Hope 5 A) and their respective parents was analyzed under field conditions. Seventeen Chinese Spring DH lines derived from wheat x Hordeum bulbosum crosses were also included for comparison. No significant variation was detected in either population of Chinese Spring DH lines and neither DH population differed from its parent. The Hope DH lines differed significantly for tiller biomass, spikelet number per ear, ear grain weight and 50-grain weight. However, all the variation could be attributed to the poor performance of only one line. Chinese Spring (Hope 5 A) DH lines showed significant variation for ear emergence time, but this was probably due to genetic heterogeneity in the parental stock. Overall, the results suggest that most DH lines produced by the wheat x maize method resemble their wheat parent, and that the variation induced in DH production is likely to be similar to that found in DHs from wheat x Hordeum bulbosum crosses.     

Changes in the fatty acid unsaturation after hardening in wheat chromosome substitution lines with different cold tolerance

Two wheat (Triticum aestivum L.) varieties, Cheyenne (Ch, winter wheat with excellent frost tolerance) and Chinese Spring (CS, spring wheat with weak frost tolerance), and chromosome substitution lines (CS/Ch 5A, CS/Ch 5D, CS/Ch 7A) created from Cheyenne and Chinese Spring were used to study the effect of chromosome substitutions on the membrane lipid composition in the leaves and crowns before and after cold hardening. The percentage of fatty acid unsaturation in phosphatidylethanolamine was greater in the crown of hardened Cheyenne than in Chinese Spring. The value of CS/Ch 5A was similar to Cheyenne and that of CS/Ch 5D to Chinese Spring, while the value of CS/Ch 7A was in between those of Cheyenne and Chinese Spring. A smaller difference was found between the unsaturation level in the phosphatidylcholine from Cheyenne and Chinese Spring after hardening, while the value obtained for the substitution line CS/Ch 7A was similar to Cheyenne. The percentage decrease in thetrans-Δ³-hexadecenoic acid content was found to be correlated with the frost tolerance of the wheat genotypes.     

Quantitative Trait Loci for Aluminum Resistance in Wheat Cultivar Chinese Spring

Aluminum (Al) toxicity is one of the major constrains for wheat production in many wheat growing areas worldwide. Further understanding of inheritance of Al resistance may facilitate improvement of Al resistance of wheat cultivars (Triticum aestivum L.). A set of ditelosomic lines derived from the moderately Al-resistant wheat cultivar Chinese Spring was assessed for Al resistance. The root growth of ditelosomic lines DT5AL, DT7AL, DT2DS and DT4DS was significantly lower than that of euploid Chinese Spring under Al stress, suggesting that Al-resistance genes might exist on the missing chromosome arms of 5AS, 7AS, 2DL and 4DL of Chinese Spring. A population of recombinant inbred lines (RILs) from the cross Annong 8455 × Chinese Spring-Sumai 3 7A substitution line was used to determine the effects of these chromosome arms on Al resistance. A genetic linkage map consisting of 381 amplified fragment length polymorphism (AFLP) markers and 168 simple sequence repeat (SSR) markers was constructed to determine the genetic effect of the quantitative trait loci (QTLs) for Al resistance in Chinese Spring. Three QTLs, Qalt.pser-4D, Qalt.pser-5A and Qalt.pser-2D, were identified that enhanced root growth under Al stress, suggesting that inheritance of Al resistance in Chinese Spring is polygenic. The QTL with the largest effect was flanked by the markers of Xcfd23 and Xwmc331 on chromosome 4DL and most probably is multi-allelic to the major QTL identified in Atlas 66. Two additional QTLs, Qalt.pser-5A and Qalt.pser-2D on chromosome 5AS and 2DL, respectively, were also detected with marginal significance in the population. Some SSR markers identified in this study would be useful for marker-assisted pyramiding of different QTLs for Al resistance in wheat cultivars.     

一种小麦蓝粒标记单体代换系4E（3D）的创制

以中国春3D单体和小麦-长穗偃麦草4E二体异附加系为材料,通过杂交、回交结合染色体鉴定等方法,培育出了一种具有蓝粒标记的小麦4E(3D)单体代换系.该小麦4E(3D)单体代换系籽粒为浅蓝色,能够正常生长,自交结实率为36.1%,其自交后代可分离出深蓝籽粒小麦4E(3D)二体代换系、浅蓝籽粒小麦4E(3D)单体代换系和白粒小麦3D缺体.结果表明,长穗偃麦草4E染色体对小麦3D染色体缺失有一定的补偿功能,对以染色体定向代换方式快速创制蓝粒标记小麦单体系统具有一定的参考价值.     

Mapping QTLs controlling grain yield and its components on chromosome 5A of wheat

Chromosome 5A of wheat is known to carry a number of genes affecting adaptability and productivity. To localize quantitative trait loci (QTLs) controlling grain yield and its components, an RFLP map was constructed from 118 single-chromosome recombinant lines derived from the F₁ between Chinese Spring (Cappelle-Desprez 5A) and Chinese Spring (Triticum spelta 5A). The map was combined with the field-trial data scored over 3 years. A total of five regions in chromosome 5A contributed effects on yield traits. Increases in grain yield, 50-grain weight and spikelet number/ear were determined by complementary QTL alleles from both parents. The effects associated with the vernalization requirement gene Vrn-A1 or a closely linked QTL were significant only in the favorable growing season where the later-flowering vrn-A1 allele from Cappelle-Desprez 5A produced a higher tiller number/plant and spikelet number/ear. The effects of the ear morphology gene q or closely linked QTL(s) were detected for grain yield and ear grain weight. Three other QTLs with minor effects were dispersed along chromosome 5A. These QTLs had large interactions with years due to changes in the magnitude of the significant response. The alleles from T. spelta, however, conferred a higher yield performance. Received: 18 August 1999 / Accepted: 25 March 2000     

Effect of individual Sumai 3 chromosomes on resistance to scab spread within spikes and deoxynivalenol accumulation within kernels in wheat

Two sets of substitution lines were developed by crossing individual monosomic lines of Chinese Spring (recipient) with scab (Fusarium graminearum) resistant cultivar Sumai 3 (donor) and then using the monosomics as the recurrent male parent for four backcrosses (without selfing after each backcross). The disomic substitution lines were separated from selfed BC4F2 plants. Chromosome specific SSR markers were analyzed for polymorphism between Sumai 3 and Chinese Spring. Polymorphic markers were used to identify substitution lines for specific chromosomes. Based on the specific SSR markers, chromosome substitutions occurred in thirty-six lines, and six lines segregated alleles from the two parents or were homozygous for the allele from Chinese Spring. These substitution lines were used to evaluate Type II (spread within the head) and Type V (deoxynivalenol accumulation within kernels) scab resistance. The objective was to use the substitution lines to evaluate the effect of individual chromosomes of Sumai 3 on Type 11 and Type V scab resistance in the greenhouse. Significant differences in Type II scab resistance and deoxynivalenol (DON) levels among different Chinese Spring (Sumai 3) substitution lines were detected. Positive chromosome substitution effects on Type II scab resistance were found on chromosomes 2B, 3B. 6B, and 7A from Sumai 3. Chromosomes 3B and 7A also reduced DON accumulation within the kernels, while chromosomes IB, 2D, and 4D from Sumai 3 increased DON concentration. Chromosome 7A from Sumai 3 had the largest effect on resistance to scab spread and DON accumulation. Additional research is in progress on the scab resistance conferred by chromosome 7A.     

用Langdon二体代换系统建立小麦染色体RAPD标记

以一套Ｌａｎｇｄｏｎ硬粒小麦二体代换系及其亲本Ｌａｎｇｄｏｎ、中国春和中国春双端体为材料,研究适于硬粒小麦和普通小麦的理想ＲＡＰＤ分析条件,进行小麦Ａ、Ｂ和Ｄ染色体组各个染色体的ＲＡＰＤ分析。结果表明,ＡｍｐｌｉＴａｑＳｔｏｆｆｅｌｆｒａｇｍｅｎｔ比ＴａｑＤＮＡＰｏｌｙｍｅｒａｓｅ优越。所用１２个随机引物中,７个引物扩增出的１３个特异产物,可确定在硬粒小麦ＬａｎｇｄｏｎＡ、Ｂ染色体组和中国春Ｄ染色体组中的１０个个别染色体上。４个标记进一步定位在相应的４个染色体臂上。结果还表明,用Ｌａｎｇｄｏｎ二体代换系统、中国春双端体为材料,容易得到重复性高、特异性强的ＲＡＰＤ标记。     

长穗偃麦草基因组中与耐低磷营养胁迫有关的基因的染色体定位

以中国春－长穗偃麦草二体异附加系和二体异代换系为材料，对其耐低磷营养胁迫特性进行鉴定和遗传分析，结果表明（１）长穗偃麦草的４Ｅ一＾ 色体携有耐低营养胁迫的基因，且其效应远远超过背景亲本中国春。     

Identification of adult plant resistance to stripe rust in the wheat cultivar Cappelle-Desprez

Following the appearance of stripe rust in South Africa in 1996, efforts have been made to identify new sources of durable resistance. The French cultivar Cappelle-Desprez has long been considered a source of durable, adult plant resistance (APR) to stripe rust. As Cappelle-Desprez contains the seedling resistance genes Yr3a and Yr4a, wheat lines were developed from which Yr3a and Yr4a had been removed, while selecting for Cappelle-Desprez derived APR effective against South African pathotypes of the stripe rust fungus, Puccinia striiformis f. sp. tritici. Line Yr16DH70, adapted to South African wheat growing conditions, was selected and crossed to the stripe rust susceptible cultivar Palmiet to develop a segregating recombinant inbred line mapping population. A major effect QTL, QYr.ufs-2A was identified on the short arm of chromosome 2A derived from Cappelle-Desprez, along with three QTL of smaller effect, QYr.ufs-2D, QYr.ufs-5B and QYr.ufs-6D. QYr.ufs-2D was located within a region on the short arm of chromosome 2D believed to be the location of the stripe rust resistance gene Yr16. An additional minor effect QTL, QYr.ufs-4B, was identified in the cv. Palmiet. An examination of individual RILs carrying single or combinations of each QTL indicated significant resistance effects when QYr.ufs-2A was combined with the three minor QTL from Cappelle-Desprez, and between QYr.ufs-2D and QYr.ufs-5B.     

Leaf dehydroascorbate reductase and catalase activity is associated with soil drought tolerance in bread wheat

A number of morphological, physiological and phenological traits have been suggested as significant markers of adaptation to drought in bread wheat (Triticum aestivum L.). This study was aimed at the identification of a relationship between dehydroascorbate reductase (DHAR, EC 1.8.5.1) and catalase (CAT, EC 1.11.1.6) activities in leaves of wheat plants and stability of yield components under water deficit. The single chromosome substitution lines of cv. Chinese Spring carrying separate chromosomes from the donor Synthetic 6x, an artificial hexaploid combining the genomes of the two wild species, Triticum dicoccoides (AABB) and Aegilops tauschii (DD), were the objects of the investigations. The activities of the DHAR and CAT were correlated with flag leaf relative water content and two indexes of stability of grain yield components under drought across the set substitution lines. The lines carrying a synthetic hexaploid homologous pair of chromosomes 1B, 1D, 2D, 3D or 4D all expressed a low constitutive level of DHAR and the lines carrying chromosomes 3B, 1D, 2D and 3D a low constitutive level of CAT. All were able to increase this level (by fourfold for DHAR and by 1.5-fold for CAT) in response to stress caused by water deficit. When challenged by drought stress, these lines tended to be the most effective in retaining the water status of the leaves and preventing the grain yield components from being compromised. The discovered genetic variability for enzymes activity in leaves of wheat might be a useful selection criterion for drought tolerance.     

Physical mapping of <Emphasis Type="Italic">puroindoline b</Emphasis>-<Emphasis Type="Italic">2</Emphasis> genes and molecular characterization of a novel variant in durum wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L.)

The puroindoline genes (Pina and Pinb) are the functional components of the common or bread wheat (Triticum aestivum L.) grain hardness locus that are responsible for kernel texture. In this study, four puroindoline b-2 variants were physically mapped using nulli-tetrosomic lines of bread wheat cultivar Chinese Spring and substitution lines of durum wheat (Triticum turgidum L.) cultivar Langdon. Results indicated that Pinb-2v1 was on 7D of Chinese Spring, Pinb-2v2 on 7B of Chinese Spring, Pinb-2v3 on 7B of Chinese Spring and Langdon, and Pinb-2v4 on 7A of Chinese Spring and Langdon. A new puroindoline b-2 variant, designated Pinb-2v5, was identified at the puroindoline b-2 locus of durum wheat cultivar Langdon, with a difference of only five single nucelotide polymorphisms compared with Pinb-2v4. Sequencing results indicated that, in comparison with the Pinb-2v3 sequence (AM99733 and GQ496618 with one base-pair modification of G to T at 6th position, designated Pinb-2v3a) in bread wheat cultivar Witchta, the coding region of Pinb-2v3 in 12 durum wheat cultivars had a single nucleotide change from T to C at the 311th position, resulting in a corresponding amino acid change from valine to alanine at the 104th position. This new allele was designated Pinb-2v3b. The study of puroindoline b-2 gene polymorphism in CIMMYT and Italian durum wheat germplasm and discovery of a novel puroindoline b-2 variant could provide useful information for further understanding the molecular and genetic basis of kernel hardness and illustrating gene duplication events in wheat.     

Genetic analysis of anther culture response in wheat using aneuploid,chromosome substitution and translocation lines

Summary Marked effects of genotype on wheat anther culture response have been observed. Genetic factors have been recognised to be one of the major contributors to in vitro responses of cultured wheat tissues. In wheat anther culture, embryo induction, plant regeneration and albina/green ratio have been determined to be heritable traits. Using Chinese Spring (CS) monosomic 1D, single chromosome substitution lines of chromosome 5B or chromosome arm 5BL from Chinese Spring into six varieties, and F₁ hybrids heterozygous for the 1B chromosome structure (1BL-1BS/1BL-1RS), the anther culture response was studied: genes on CS1D chromosome and 5BL chromosome arm increases the embryo frequency; gene(s) involved in regeneration ability are located on the 1RS chromosome arm; a gene increasing albina frequency is located on Chinese Spring 5B chromosome. Our results support the fact that without gametic selection, a differential development occurred from the particular classes of microspores carrying genes for higher regeneration ability. Moreover, in some crosses, a few genes with major effects were involved in determination of anther culture response.     

Identification of wheat (Triticum aestivum L.) chromosomes with genes controlling the level of nitrate reductase,nitrite reductase,and acid proteinase using the Chinese Spring-Hope substitution lines

The levels of nitrate reductase, nitrite reductase, and acid proteinase were compared in the primary leaves of 8-day-old wheat seedlings of Chinese Spring, Hope, and the 21 disomic substitution lines of Hope in Chinese Spring. Two chromosomes, 7B and 7D, were considered to contain genes controlling the level of nitrate reductase. Substitution of Hope chromosome 7B caused a highly significant increase in the in vitro stability of nitrate reductase. Nitrite reductase appeared to be controlled by two major genes, located on chromosomes 4D and 7D, and two minor genes, located on chromosomes 3D and 5A. In the case of acid proteinase, substitution of chromosome 1D caused a significant reduction in enzyme activity.     

应用基因组原位杂交及RFLP标记鉴定小麦中的大麦染色体

用生物素（Biotin-6-dUTP)标记的大麦Betzes基因组DNA作探针,以普通小麦中国春总DNA作封阻进行基因组原位杂交（Genomeinsituhybridization,简称GISH）,从13株小麦-大麦杂交后代中鉴定出2个含有3条大麦Betzes2H染色体的材料（2n＝43）;2个2H单体异代换系（2n＝42）;7个2H二体异代换系（2n＝42）。用已定位在小麦第2部分同源群短臂上的探针psr131进行RFLP分析,结果表明大麦Betzes、代换系A5有1条区别于小麦中国春的特异带,A     

The role of chromosomes from homeologous group 5 in regulation of grain hardness and protein content in substitution lines of common wheat cultivar Saratovskaya 29

Genetic regulation of grain hardness and protein content in intervarietal substitution lines for chromosomes of homeologous group 5 was examined. Common wheat cultivar Saratovskaya 29 with high bread-backing properties served as the recipient. Donors of chromosomes 5A and 5D were 18 cultivars with variable traits examined, including high-protein cultivars (Atlas 66 and Diamant 2), and soft-grain cultivars (Ul’yanovka and Chinese Spring). Analysis of substitution lines pointed to a substantial effect of chromosome 5D on the regulation of both traits. It was demonstrated that as a result of intervarietal substitution for chromosome 5D from donor cultivars Ul’yanovka and Chinese Spring, the endosperm softness was increased compared to the recipient cultivar Saratovskaya 29. Substitution lines Saratovskaya 29/Atlas 66 5D and Saratovskaya 29/Diamant 2 5D were characterized by high grain protein content, as well as by high endosperm hardness. In addition, the line Saratovskaya 29/Novosibirskaya 67 5D, characterized by grain hardness higher than in Saratovskaya 29, was isolated. In the lines with intervarietal substitution of chromosome 5A, grain protein content was found to be lower than in recipient cultivar Saratovskaya 29.     

Physiological basis of reduced Al tolerance in ditelosomic lines of Chinese Spring wheat

Aluminum tolerance was assessed in the moderately Al-tolerant wheat (Triticum aestivum L.) cultivar Chinese Spring and a set of ditelosomic lines derived from Chinese Spring. Three ditelosomic lines lacking chromosome arms 4DL, 5AS and 7AS, respectively, exhibited decreased Al tolerance relative to the euploid parent Chinese Spring based on reduced root growth in Al-containing solutions. The physiological basis of the reduced Al tolerance was investigated. Measurements by inductively coupled argon plasma mass spectroscopy of root apical Al accumulation demonstrated that two of these three lines had a decreased ability to exclude Al from the root apex, the site of Al phytotoxicity. As Al-induced malate exudation has been suggested to be an important physiological mechanism of Al tolerance in wheat, this parameter was quantified and malate exudation was shown to be smaller in all three deletion lines compared with Chinese Spring. These results suggest that the decreased Al tolerance in at least two of the three ditelosomic lines is due to the loss of different genes independently influencing a single Al-tolerance mechanism, rather than to the loss of genes encoding alternative Al-tolerance mechanisms. Received: 3 July 2000 / Accepted: 9 August 2000     

Genotypic variation in tetraploid wheat affecting homoeologous pairing in hybrids with Aegilops peregrina.

The Ph1 gene has long been considered the main factor responsible for the diploid-like meiotic behavior of polyploid wheat. This dominant gene, located on the long arm of chromosome 5B (5BL), suppresses pairing of homoeologous chromosomes in polyploid wheat and in their hybrids with related species. Here we report on the discovery of genotypic variation among tetraploid wheats in the control of homoeologous pairing. Compared with the level of homoeologous pairing in hybrids between Aegilops peregrina and the bread wheat cultivar Chinese Spring (CS), significantly higher levels of homoeologous pairing were obtained in hybrids between Ae. peregrina and CS substitution lines in which chromosome 5B of CS was replaced by either 5B of Triticum turgidum ssp. dicoccoides line 09 (TTD09) or 5G of Triticum timopheevii ssp. timopheevii line 01 (TIMO1). Similarly, a higher level of homoeologous pairing was found in the hybrid between Ae. peregrina and a substitution line of CS in which chromosome arm 5BL of line TTD140 substituted for 5BL of CS. It appears that the observed effect on the level of pairing is exerted by chromosome arm 5BL of T turgidum ssp. dicoccoides, most probably by an allele of Ph1. Searching for variation in the control of homoeologous pairing among lines of wild tetraploid wheat, either T turgidum ssp. dicoccoides or T timopheevii ssp. armeniacum, showed that hybrids between Ae. peregrina and lines of these two wild wheats exhibited three different levels of homoeologous pairing: low, low intermediate, and high intermediate. The low-intermediate and high-intermediate genotypes may possess weak alleles of Ph1. The three different T turgidum ssp. dicoccoides pairing genotypes were collected from different geographical regions in Israel, indicating that this trait may have an adaptive value. The availability of allelic variation at the Ph1 locus may facilitate the mapping, tagging, and eventually the isolation of this important gene.     

Chromosomal assignment of gene sequences coding for protein disulphide isomerase (PDI) in wheat

 Three different probes, obtained by PCR amplification and labelling of different segments of a PDI cDNA clone from common wheat, were used to identify and assign to wheat chromosomes the gene sequences coding for protein disulphide isomerase (PDI). One of these probes, containing the whole coding region except for a short segment coding for the C-terminal sequence, displayed defined and specific RFLP patterns. PDI gene sequences were consequently assigned to wheat chromosome arms 4BS, 4DS, 4AL and 1BS by Southern hybridisation of EcoRI- HindIII- and BamHI-digested total DNA of nulli-tetrasomic and di-telosomic lines of Chinese Spring. This probe was also employed for assessing the restriction fragment length polymorphism in several hexaploid and tetraploid cultivated wheats. These showed considerable conservation at PDI loci; in fact polymorphism was only observed for the chromosome 1B fragment. Received: 7 July 1998 / Accepted: 14 August 1998     

小麦细胞质雄性不育与不同核基因组及其染色体的关系

本文用１７个中国春小麦的缺体四体、９种不同的核基因组小麦与Ｇ、Ｓ￣ｕ、Ｍ￣ｏ、Ｄ￣２型细胞质中国春小麦杂交,探讨这４种异细胞质中国春小麦的育性与不同染色体、核基因组的关系。实验结果表明,某些染色体对这４种细胞质或某一细胞质类型的育性有影响;某些核基因组对这４种细胞质或某一细胞质类型的育性有较大的影响。     

Mechanism of durable resistance: a new approach

Summary Wheat genotypes, including backcross derivatives of Thatcher carrying Lr10 and Lr23, substitution lines for Lr10 and Lr23 in Chinese Spring background and Chinese Spring and Thatcher were analysed against 21 pathotypes of leaf rust in seedling tests. Adult plant responses in all these stocks were observed in the field nurseries under exposure to the inoculum of the Indian virulent races of leaf rust. The seedling data demonstrated that both the substitution lines and the backcross derivatives for each gene carry identical pattern of infection for resistance. The high level of adult plant resistance in the substitution lines, in contrast to the backcross derivatives in Thatcher, has been postulated to be due to the combination of resistance contributed by Lr10 and adult plant Chinese Spring resistance or to Lr23 and Chinese Spring adult plant resistance. It has been suggested that genes Lr10 and Lr23 added to the Chinese Spring background provide sources for durable resistance, since Chinese Spring has continued to provide a moderate level of adult plant resistance to leaf rust for a very long time.