Common Wheat Landrace Research Articles

Characterisation of a new stripe rust resistance gene Yr47 and its genetic association with the leaf rust resistance gene Lr52

Two Iranian common wheat landraces AUS28183 and AUS28187 from the Watkins collection showed high levels of seedling resistance against Australian pathotypes of leaf rust and stripe rust pathogens. Chi-squared analyses of rust response segregation among F(3) populations derived from crosses of AUS28183 and AUS28187 with a susceptible genotype AUS27229 revealed monogenic inheritance of leaf rust and stripe rust resistance. As both genotypes produced similar leaf rust and stripe rust infection types, they were assumed to carry the same genes. The genes were temporarily named as LrW1 and YrW1. Molecular mapping placed LrW1 and YrW1 in the short arm of chromosome 5B, about 10 and 15cM proximal to the SSR marker gwm234, respectively, and the marker cfb309 mapped 8-12cM proximal to YrW1. LrW1 mapped 3-6cM distal to YrW1 in two F(3) populations. AUS28183 corresponded to the accession V336 of the Watkins collection which was the original source of Lr52. Based on the genomic location and accession records, LrW1 was concluded to be Lr52. Because no other seedling stripe rust resistance gene has previously been mapped in chromosome 5BS, YrW1 was permanently named as Yr47. A combination of flanking markers gwm234 and cfb309 with phenotypic assays could be used to ascertain the presence of Lr52 and Yr47 in segregating populations. This investigation characterised a valuable source of dual leaf rust and stripe rust resistance for deployment in new wheat cultivars. Transfer of Lr52 and Yr47 into current Australian wheat backgrounds is in progress.

Genetic differentiation of hexaploid wheat inferred from analysis of microsatellite loci

Landraces of wheat can serve as important potential sources for extending the genetic basis of selection cultivars. Analysis of microsatellites and typing of polymorphism in a representative sample of 347 genotypes, including landraces and selection cultivars, was performed using a set of 38 selected oligonucleotide primer pairs. Classification of genotypes with respect to the level of their similarity was performed using cluster analysis. The data obtained pointed to genetic differentiation of hexaploid wheat. The groups of cultivars, the formation of which was thought to be associated with the main old areas of wheat cultivation in Europe and Asia, were identified. The basis of each of the groups was formed by landraces of common wheat. The differences between the groups identified were associated with multiple changes in the wheat genome and were expressed as quantitative differences in the allele frequencies of microsatellite loci. The results of the study are of interest in terms of understanding the structure of wheat genetic diversity and revealing the pathways of evolution of this culture.

Molecular Mapping of Powdery Mildew Resistance Gene <I>MlWE29</I> in Wheat Originated from Wild Emmer (<I>Triticum turgidum</I> var.<I>Dicoccoides</I>)

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in many re- gions in the world. Breeding for resistance is the most economical and effective method for controlling this disease. Wild emmer (Triticum turgidum var. dicoccoides) is the immediate progenitor of cultivated tetraploid and hexaploid wheats and has been proven to be an important resource of disease resistance improvement. In this study, a common wheat line 3D258 with powdery mildew resistance was developed by crossing wild emmer accession WE29 with common wheat landrace Yanda1817 and back- crossing with common wheat line 87-1 (Yanda 1817/WE29//5*87-1, BC4F6). Genetic analysis of the F2 population and their F3 families, developed from 3D258 and a susceptible common wheat cultivar Xuezao, indicated that the powdery mildew resistance in 3D258 was controlled by a single dominant gene, designated temporarily as MlWE29. Molecular markers and the bulked seg- regant analysis were used to characterize the powdery mildew resistance gene MlWE29. Six SSR markers (Xgwm335, Xgwm213, Xgwm639, Xwmc415, Xwmc289, and Xwmc75) and five EST-STS markers (BE494426, BE442763, CD452476, BE445282, and BE407068) were found to be linked to MlWE29. Using Chinese Spring nullisomic-tetrasomics, ditelosomics and deletion lines,

Comparative analysis of the homoeologous pairing effects ofphKLgene in common wheat ×Psathyrostachys huashanicaKeng ex Kuo

In the natural populations of common wheat landrace Kaixianluohanmai, there was a phKL gene which promotes homoeologous pairing of wheat-alien hybrids. In the present study, the effects of phKL gene on crossability and homoeologous pairing of Triticum aestivum × Psathyrostachys huashanica Keng ex Kuo hybrids were comparatively analyzed. The crossability of the hybrid between Sichuan wheat landrace Kaixianluohanmai and P. huashanica was highest in all the hybrid combinations with 3.18%. The hybrids T. aestivum (Kaixianluohanmai) × P. huashanica showed a pairing configuration of 21.70 univalents + 2.68 rod bivalents + 0.34 ring bivalents + 0.06 trivalents + 0.02 quadrivalents and 3.54 chiasma per PMC at MI. However, the chiasma in hybrids of CS, CS ph1b, CS ph2a and CS ph2b with P. huashanica was 0.56, 1.90, 0.87 and 0.60, respectively. Compared with the hybrids of CS, CS ph1b, CS ph2a and CS ph2b with P. huashanica, a significant increase in the chiasma of homoeologous pairing was observed in the hybrids of T. aestivum (Kaixianluohanmai) × P. huashanica. The effects were shown in the increment of rod bivalents, ring bivalents and trivalents and reduction of univalents. The results indicated that phKL showed a higher effect on promoting homoeologous pairing than ph1 and ph2 in T. aestivum × P. huashanica. The wheat landrace Kaixianluohanmai with phKL gene is probably a more desirable material for alien gene transferring than Ph2 -deficiency lines.

Evaluation of genetic variation in high molecular weight glutenin subunits of seed storage protein using landraces of common wheat from Pakistan

SDS-PAGE was used to determine the variation in high molecular weight glutenin subunits (HMW-GS) alleles present in 170 landraces of common wheat from Sindh, Balochistan and NWFP in Pakistan. Three alleles for Glu-A1, six alleles for Glu-B1 and four alleles for Glu-D1 were detected. These included three new alleles, namely Glu-B1e, Glu-B1h and Glu-D1n, which had not previously been found in landraces of Pakistani wheat. Furthermore, Glu-D1m and Glu-D1n, which are considered to be endemic alleles in Pakistan and Afghanistan, were both detected from Balochistan. Twenty genotypes were identified based on combinations of alleles at the three Glu-1 loci. The present study showed that Pakistani landraces of common wheat have maintained a broad diversity of HMW-GS alleles, and that they may serve as genetic resources to improve wheat varieties adapted to Pakistani climatic and edaphic conditions.

Geographic Distribution of Stem Rust Resistance in Wheat Landraces

Wheat stem rust, caused by Puccinia graminis Pers.:Pers f. sp. tritici Eriks. & Henn., is of renewed concern due to the emergence of a new virulent race in East Africa. Landrace accessions of common wheat (Triticum aestivum L. subsp. aestivum) and durum wheat (T. turgidum L. subsp. durum) from the National Small Grains Collection (NSGC) could be sources of new stem rust resistance genes. In an effort to better target the screening of NSGC landrace accessions against the new race, data from the NSGC were analyzed for the geographic distribution of resistance. We used data from U.S. screening trials for 5700 landrace accessions of common wheat and 2719 of durum wheat. Areas with a high incidence of stem rust resistance were found in Ethiopia, Chile, Turkey, Bosnia and Herzegovina, and adjacent areas of the former Yugoslavia. Resistance to multiple races at the seedling stage was most frequent in accessions from Ethiopia and Turkey. Resistance in durum wheat was more frequent than resistance in common wheat. The distribution of the areas with high incidence of resistant durum landraces was similar to that for common wheat landraces. A logistic regression model predicting resistance in common wheat accessions (n = 3607) from 10 traits identified 192 previously untested accessions with a greater than 50% chance of being resistant. Based on this model and on the identification of geographic centers for resistance, accessions will be prioritized for future screening against new stem rust races.

Genetic diversity of HMW glutenin subunit in Chinese common wheat (Triticum aestivum L.) landraces from Hubei province

The high molecular weight (HMW) glutenin subunit composition of 111 common landraces of bread wheat collected from Hubei province, China has been determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Ninety six of the accessions were homogeneous for HMW glutenin subunit composition and 15 were heterogeneous. For the Glu-1 loci, 16 alleles were detected, 3 at the Glu-A1locus, 9 at the Glu-B1and 4 at the Glu-D1. Three novel alleles were identified, two at the Glu-B1 and one at the Glu-D1locus. Combination of these 16 alleles resulted in 14 different HMW subunit patterns. The distribution of HMW glutenin subunit alleles in a subset of 105 of the 111 accessions representing six populations was assessed both at the individual population and whole population levels. The results demonstrated that the distribution of allelic patterns varied among populations. Taken together, 62.5% of the alleles detected were considered to be rare alleles while the Glu-A1c (null), Glu-B1b (1Bx7 + 1By8) and Glu-D1a (1Dx2 + 1Dy12) alleles were found most frequently in the six populations. The subset exhibited relatively high genetic diversity (A = 5.33, P = 1.00, Ae = 1.352 and He = 0.238) with 81.5% of the diversity being within populations and 18.5% between populations.

Genetic control of the spring growth habit in old local cultivars and landraces of common wheat from Siberia

The inheritance of the spring habit was studied in 63 old local cultivars and landraces of common wheat from Eastern and Western Siberia and the Tyva Republic. Minimal polymorphism was observed for the dominant Vrn genes, controlling the spring habit in landraces of these regions. The control was digenic and involved the Vrnl and Vrn2 dominant genes in the majority (95%) of cultivars and was monogenic in three cultivars. None of the cultivars had the Vrn3 dominant gene, characteristic of the neighboring regions of China and Central Asia. Among 137 old local cultivars and landraces of Siberia, only one (cultivar Sibirskaya (k-23347) from Irkutsk oblast, was comparable in the response to the natural short day (photoperiod) to Chinese cultivars. Comparison of the results and the data reported for commercial cultivars revealed that the genotype frequencies of the dominant Vrn genes in Siberian landraces and commercial cultivars of common wheat remained essentially unchanged at least for the past 100 years. At the same time, Siberian landraces significantly differed in Vrn dominant gene frequencies from cultivars of the adjacent regions. It was assumed that the control of the spring habit by the two Vrn dominant genes is optimal for the climatic conditions of Siberia.

Characterization of a Novel High-Molecular-Weight Glutenin Subunit Pair 2.6 + 12 in Common Wheat Landraces in the Xinjiang Uygur Autonomous District of China

Characterization of a Novel High-Molecular-Weight Glutenin Subunit Pair 2.6 + 12 in Common Wheat Landraces in the Xinjiang Uygur Autonomous District of China

Assessment of storage protein variation in relation to some morphological characters in a sample of Spanish landraces of common wheat (Triticum aestivum L. ssp. aestivum)

Fifty nine Spanish landraces of common wheat belonging to differentagrotypes were evaluated with four morphological spike characters and 11 seedprotein loci in order to study the level of agreement between the agrotypeclassification and the morphological and biochemical variation of the wheats. Asa result of the work 22 new gliadin alleles were found and 12 of them werecatalogued. Multivariate and cluster analysis performed on the two sets of data(morphological plus biochemical and biochemical only) showed that there was aclear relationship between seed protein composition and the wheat classificationfor the agrotypes ‘Barbilla’, ‘Candeal’ and‘Negrete’. For the other groups, agrotype classification was notconsistent with the variation for biochemical characters although, some allelesin common were found except for the ‘Jeja’ type. Morphologicaltraits revealed that they could be useful as first step in discriminating amongagrotypes. In contrast, biochemical markers showed that genetic variation amongaccessions was higher than among agrotypes. The protein lociGli-B1,Gli-A2,Gli-D2 andGli-A1 were shown to be the mostpolymorphic and useful in discriminating between the accessions studied.

Chromosomal location of genes for resistance to powdery mildew in common wheat (Triticum aestivum L. em. Thell.) 4. Gene Pm 24 in Chinese landrace Chiyacao

Chinese wheat landrace Chiyacao exhibited a response pattern different from that of the cultivars/lines possessing documented Pm genes after inoculation with 106 isolates of Erysiphe graminis f. sp. tritici. To characterize this resistance and to determine the chromosomal location of the gene or genes present, we crossed the landrace to susceptible cultivar ‘Chinese Spring’ and also to a set of 21 ‘Chinese Spring’ monosomic lines. Monosomic F1 plants were allowed to self-pollinate and to produce F2 seeds. Seedlings of F2 plants and their parents were inoculated with isolates nos. 5 and 12 of Erysiphe graminis f. sp. tritici. The results revealed that one major dominant gene is located on chromosome 6D of Chinese common wheat landrace Chiyacao. The new gene is designated Pm 24.