Genetic diversity of resistance genes controlling fusarium head blight with simple sequence repeat markers in thirty-six wheat accessions from east asian origin

Summary Fusarium head blight (FHB) is a serious disease of wheat worldwide that may cause substantial yield and quality losses. Breeding for FHB-resistant cultivars is the most cost-effective approach to control FHB. The objective of the present study was to determine the relationship of resistance between new resistant sources and Sumai 3 using five simple sequence repeat (SSR) markers closely linked to the major QTL for FHB resistance on chromosome arms 3BS and 6BS. All five SSR markers were highly polymorphic between Sumai 3 (and its derivatives) and susceptible Canadian wheat lines. Most of the Sumai 3-derived Chinese wheat accessions and three Canadian FHB-resistant lines had all the Sumai 3 SSR marker alleles on chromosome arms 3BS and 6BS. The Chinese landrace Wangshuibai and two Japanese accessions Nobeokabozu and Nyu Bai had the same banding patterns as Sumai 3 for all five SSR marker alleles, and another Chinese landrace Fangshanmai had three of the five SSR markers in common with Sumai 3, and therefore most likely carries the same QTL as Sumai 3 on 3BS and 6BS. The Brazilian cultivar Frontana had no alleles in common with Sumai 3 on either QTL, and the Chinese landrace Hongheshang had only one of the five SSR markers in common with Sumai 3, therefore likely carrying resistance genes different from Sumai 3. The Italian cultivar Funo is not the donor of either the 3BS QTL or 6BS QTL. All five SSR seem to be effective candidates for marker-assisted selection to increase the level of resistance to FHB in wheat breeding programs.     

Quantitative trait loci for resistance to Fusarium head blight in the Chinese wheat landrace Huangfangzhu

The Chinese wheat landrace Huangfangzhu (HFZ) has a high level of resistance to Fusarium head blight (FHB). To identify chromosomal regions that are responsible for FHB resistance in HFZ, F₈ recombinant inbred lines (RIL) were developed from a cross between HFZ and Wheaton, a U.S. hard spring wheat. FHB was evaluated by single floret inoculation in both greenhouse and field environments. Two quantitative trait loci (QTL) with major effects were identified. One QTL was located on the short arm of chromosome 3B, and explained 35.4% of the phenotypic variation; the other QTL was assigned to 7AL and explained 18.0% of the phenotypic variation for FHB response. In addition, three minor QTL were detected on chromosomes 1AS, 1B and 5AS by single marker regression. HFZ contributed all favorable alleles. The RIL with HFZ alleles at the QTL on 3BS and 7AL displayed significantly lower percentages of infected spikelets than RIL without these alleles in both greenhouse and field environments. HFZ combined several alleles from germplasm reported previously and is a promising alternative source for improving wheat FHB resistance.     

Molecular characterization of <Emphasis Type="Italic">Fusarium</Emphasis> head blight resistance from wheat variety Wangshuibai

Fusarium head blight (FHB) is a destructive disease of wheat worldwide. FHB resistance genes from Sumai 3 and its derivatives such as Ning 7840 have been well characterized through molecular mapping. In this study, resistance genes in Wangshuibai, a Chinese landrace with high and stable FHB resistance, were analyzed through molecular mapping. A population of 104 F₂-derived F₇ recombinant inbred lines (RILs) was developed from the cross between resistant landrace Wangshuibai and susceptible variety Alondras. A total of 32 informative amplified fragment length polymorphism (AFLP) primer pairs (EcoRI/MseI) amplified 410 AFLP markers segregating among the RILs. Among them, 250 markers were mapped in 23 linkage groups covering a genetic distance of 2,430 cM. In addition, 90 simple sequence repeat (SSR) markers were integrated into the AFLP map. Fifteen markers associated with three quantitative trait loci (QTL) for FHB resistance (P < 0.01) were located on two chromosomes. One QTL was mapped on 1B and two others were mapped on 3B. One QTL on 3BS showed a major effect and explained up to 23.8% of the phenotypic variation for type II FHB resistance.     

QTL mapping and marker-assisted selection for Fusarium head blight resistance in wheat: a review

During the past decade, numerous studies have been published on molecular mapping of Fusarium head blight (FHB) resistance in wheat. We summarize the relevant findings from 52 quantitative trait loci (QTL) mapping studies, nine research articles on marker-assisted selection and seven on marker-assisted germplasm evaluation. QTL for FHB resistance were found on all wheat chromosomes except chromosome 7D. Some QTL were found in several independent mapping studies indicating that such QTL are stable and therefore useful in breeding programmes. We summarize and update current knowledge on the genetics of FHB resistance in wheat resulting from QTL mapping investigations and review and suggest FHB breeding strategies based on the available information and DNA markers.     

Quantitative trait loci for resistance to Fusarium head blight in recombinant inbred wheat lines from the cross Huapei 57-2 / Patterson

Fusarium head blight (FHB), primarily caused by Fusarium graminearum in North America, often results in significant losses in yield and grain quality of wheat (Triticum aestivum L.). Evaluation of FHB resistance is laborious and can be affected by environmental conditions. The development of DNA markers associated with FHB quantitative trait loci (QTL) and their use in breeding programs could greatly enhance selection. The objective of this study was to identify the location and effect of QTLs for FHB resistance using simple sequence repeat (SSR) markers. A population of wheat recombinant inbred lines derived from the cross ‘Huapei57-2’/‘Patterson’ was characterized for type II resistance in one field experiment and two tests under controlled conditions in the greenhouse. Bulked segregant analysis followed by QTL mapping was used to identify the major segregating QTLs. Results indicate that ‘Huapei 57-2’ may have the same resistance allele as ‘Sumai3’ at a QTL located on the short arm of chromosome 3B. Other QTLs of lower effect size were identified on the long arm of 3Band on chromosomes 3A and 5B. Our findings along with results from other studies demonstrate that the effect of the QTL on3BS is large and consistent across a wide range of genetic backgrounds and environments. Pyramiding this QTL with other FHB QTLs using marker-assisted selection should be effective in improving FHB resistance in a wheat breeding program. This revised version was published online in August 2006 with corrections to the Cover Date.     

Evaluation of the effects of five QTL regions on Fusarium head blight resistance and agronomic traits in spring wheat (Triticum aestivum L.)

Fusarium head blight (FHB) is an important disease of wheat (Triticum aestivum L.). The aim of this study was to determine the effects of quantitative trait locus (QTL) regions for resistance to FHB and estimate their effects on reducing FHB damage to wheat in Hokkaido, northern Japan. We examined 233 F₁-derived doubled-haploid (DH) lines from a cross between ‘Kukeiharu 14’ and ‘Sumai 3’ to determine their reaction to FHB during two seasons under field conditions. The DH lines were genotyped at five known FHB-resistance QTL regions (on chromosomes 3BS, 5AS, 6BS, 2DL and 4BS) by using SSR markers. ‘Sumai 3’ alleles at the QTLs at 3BS and 5AS effectively reduced FHB damage in the environment of Hokkaido, indicating that these QTLs will be useful for breeding spring wheat cultivars suitable for Hokkaido. Some of the QTL regions influenced agronomic traits: ‘Sumai 3’ alleles at the 4BS and 5AS QTLs significantly increased stem length and spike length, that at the 2DL QTL significantly decreased grain weight, and that at the 6BS QTL significantly delayed heading, indicating pleiotropic or linkage effects between these agronomic traits and FHB resistance.     

QTL analysis of resistance to Fusarium head blight in wheat using a 'Wangshuibai'-derived population

Fusarium head blight (FHB) is a devastating disease that reduces the yield, quality and economic value of wheat. For quantitative trait loci (QTL) analysis of resistance to FHB, F₃ plants and F_3:5 lines, derived from a ‘Wangshuibai’ (resistant)/‘Seri82’(susceptible) cross, were spray inoculated during 2001 and 2002, respectively. Artificial inoculation was carried out under field conditions. Of 420 markers, 258 amplified fragment length polymorphism and 39 simple sequence repeat (SSR) markers were mapped and yielded 44 linkage groups covering a total genetic distance of 2554 cM. QTL analysis was based on the constructed linkage map and area under the disease progress curve. The analyses revealed a QTL in the map interval Xgwm533‐Xs18/m12 on chromosome 3BS accounting for up to 17% of the phenotypic variation. In addition, a QTL was detected in the map interval Xgwm539‐Xs15/m24 on chromosome 2DL explaining up to 11% of the phenotypic variation. The QTL alleles originated from ‘Wangshuibai’ and were tagged with SSR markers. Using these SSR markers would facilitate marker‐assisted selection to improve FHB resistance in wheat.     

QTL analysis of resistance to Fusarium head blight in wheat using a 'Frontana'-derived population

Fusarium head blight (FHB or head scab) has become a major limiting factor for sustainable wheat (Triticum aestivum L.) production around the world. For quantitative trait loci (QTL) analysis of resistance to FHB, F₃ plants and F_{3 : 5} lines, derived from a ‘Frontana’ (moderately resistant)/‘Seri82’ (susceptible) cross, were spray‐inoculated in 2001 and 2002, respectively. Artificial inoculations were carried out under field conditions. Of 273 SSR and AFLP markers, 250 could be mapped and they yielded 42 linkage groups, covering a genetic distance of 1931 cM. QTL analysis was based on the constructed linkage map and area under the disease progress curve (AUDPC). The analyses revealed three consistent QTLs associated with FHB resistance on chromosomes 1BL, 3AL and 7AS explaining 7.9%, 7.7% and 7.6% of the phenotypic variation, respectively, above 2 years. The results confirmed the previously described resistance QTL of ‘Frontana’ on chromosome 3AL. A combination of ‘Frontana’ resistance with ‘Sumai‐3’ resistance may lead to lines with augmented resistance expression.     

Molecular mapping of partial resistance to powdery mildew in winter wheat cultivar Folke

The Swedish winter wheat (Triticum aestivum L.) cultivar Folke has a long record of partial and race non-specific resistance to powdery mildew (caused by Blumeria graminis f. sp. tritici) in the field. The aim of the present study was to map the main genetic factors behind the partial resistance in Folke and identify molecular markers for use in marker-assisted selection. A population of 130 recombinant inbred lines was developed from a cross between Folke and the moderately susceptible spring wheat line T2038. The population was tested for powdery mildew resistance over two years at two locations in Norway and genotyped with DArT and SSR markers. Composite interval mapping detected a total of eight quantitative trait loci (QTL) for powdery mildew resistance; six with resistance from Folke on 2BS, 2DL, 5AL, 5BS and 6BS and two with resistance from T2038 on 5BS and 7AL. None of the loci with resistance from Folke mapped to chromosomal regions with known race-specific resistance genes, which confirmed the race non-specific nature of the resistance in this cultivar. The molecular markers linked to the reported QTL will be useful as a tool for selecting partial and potentially durable resistance to powdery mildew based on the resistance in Folke.     

Mapping resistance gene analogs (RGAs) in cultivated tetraploid cotton using RGA-AFLP analysis

Diseases cause significant losses in cotton production throughout the US Cotton Belt. Growing resistant cultivars can significantly improve cotton yields and effectively reduce production inputs. Disease resistance (R) genes have been isolated in numerous plant species and the R genes with domains of nucleotide binding sites (NB) and leucine rich repeats (LRR) represent the largest R gene family. Degenerate primers designed based on conserved motifs of plant disease resistance genes were used alone or in combination with AFLP primers to analyze disease resistance gene analogs (RGAs) in a recombinant inbred line (RIL) population of Pima (Gossypium barbadense) 3–79 and Upland cotton (G. hirsutum) line NM 24016. Eighty-eight polymorphic RGA markers were amplified by 8 pairs of RGA degenerate primers, while 131 polymorphic RGA-AFLP markers were produced from six pairs of RGA-AFLP primer combinations. Of the 219 polymorphic RGA and RGA-AFLP markers that were identified, 212 were assigned to 18 chromosomes and linkage groups based on existing SSR markers that are on known chromosomes. However, the RGA and RGA-AFLP markers are not evenly distributed among chromosomes in that 189 RGA and RGA-AFLP markers (88%) are assigned onto three “giant” chromosomes, i.e., C6, C12, and C15, suggesting RGA clusters in the cotton genome. Several RGA and RGA-AFLP markers were mapped to the same linkage group carrying a root-knot nematode resistance gene. The identification and mapping of RGA and RGA-AFLP markers provide a framework to facilitate marker-assisted selection of disease resistance in cotton breeding and to understand the physical relationship of cotton resistance genes.     

Characterization of Chinese wheat germplasm for resistance to Fusarium head blight at CIMMYT, Mexico

Fusarium head blight (FHB) poses a challenge for wheat breeders worldwide; there are limited sources of resistance and the genetic basis for resistance is not well understood. In the mid-1980s, a shuttle breeding and germplasm exchange program launched between CIMMYT-Mexico and China, enabled the incorporation of FHB resistance from Chinese bread wheat germplasm into CIMMYT wheat. Most of the Chinese wheat materials conserved in the CIMMYT germplasm bank had not been fully characterized for FHB reaction under Mexican environments, until 2009, when 491 Chinese bread wheat lines were evaluated in a FHB screening nursery in Mexico, and 304 (61.9 %) showed FHB indices below 10 %. Subsequent testing occurred in 2010 for plant height (PH), days to heading (DH), and leaf rust response. In 2012, 140 elite lines with good agronomic types were further evaluated for field FHB reaction and deoxynivalenol (DON) accumulation. Most of the tested lines showed good resistance: 116 (82.9 %) entries displayed FHB indices lower than 10 %, while 89 (63.6 %) had DON contents lower than 1.0 ppm. Significant negative correlations were observed between FHB traits (FHB index, DON content, and Fusarium damaged kernels) and PH, DH, and anther extrusion. A subset of 102 elite entries was selected for haplotyping using markers linked to 10 well known FHB quantitative trait loci (QTL). 57 % of the lines possessed the same 2DL QTL marker alleles as Wuhan 1 or CJ 9306, and 26.5 % had the same 3BS QTL allele as Sumai 3. The remaining known QTL were of low frequency. These materials, especially those with none of the above tested resistance QTL (26.5 %), could be used in breeding programs as new resistance sources possessing novel genes for FHB resistance and DON tolerance.     

Validation of two major quantitative trait loci for fusarium head blight resistance in Chinese wheat line W14

Identity of quantitative trait loci (QTL) governing resistance to fusarium head blight (FHB) initial infection (type I), spread (type II), kernel infection, and deoxynivalenol (DON) accumulation was characterized in Chinese wheat line W14. Ninety‐six double‐haploid lines derived from a cross of W14 × ’Pion2684’ were evaluated for FHB resistance in two greenhouse and one field experiment. Two known major QTL were validated on chromosomes 3BS and 5AS in W14 using the composite interval mapping method. The 3BS QTL had a larger effect on resistance than the 5AS QTL in the greenhouse experiments, whereas, the 5AS QTL had a larger effect in the field experiment. These two QTL together explained 33%, 35%, and 31% of the total phenotypic variation for disease spread, kernel infection, and DON concentration in the greenhouse experiments, respectively. In the field experiment, the two QTL explained 34% and 26% of the total phenotypic variation for FHB incidence and severity, respectively. W14 has both QTL, which confer reduced initial infection, disease spread, kernel infection, and DON accumulation. Therefore, marker‐assisted selection (MAS) for both QTL should be implemented in incorporating W14 resistance into adapted backgrounds. Flanking markers Xbarc133 and Xgwm493 on 3BS and Xbarc117 and Xbarc56 on 5AS are suggested for MAS.     

A QTL on chromosome 2DS of ‘Sumai 3’ increases susceptibility to <Emphasis Type="Italic">Fusarium</Emphasis> head blight in wheat

Much effort has been invested in identifying molecular markers in wheat (Triticum aestivum L.) linked to quantitative trait loci (QTL) that confer resistance to Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein) Petch]. Even after several generations of crossing and selection by many wheat breeding programs, resistance of the Chinese spring wheat cultivar ‘Sumai 3’ (PI 481542) remains among the most effective. It therefore seems that undocumented resistance QTL present in Sumai 3 were not detected in various mapping studies. Using an extremely susceptible Tibetan landrace (‘Y1193-6’; unknown pedigree) in the creation of a mapping population with Sumai 3, the objective of this research was to identify undocumented resistance QTL in Sumai 3. This was accomplished through collecting disease index (DI) and Fusarium damaged kernel (FDK) phenotypic values along with 305 Diversity Array Technology (DArT) and 52 Simple Sequence Repeat (SSR) marker genotypes on 160 F_2:6 recombinant inbred lines (RILs). Disease response evaluations were based on four (two greenhouse and two field) experiments where spray inoculation methods were used. Three QTL were identified on chromosome arms 3BS, 6BL and 2DS explaining 26.1, 10.7 and 18.9% of the phenotypic variation for DI, respectively. The same QTL were also significantly associated with reduced FDK scores and explained 28.0, 11.0 and 23.0% of phenotypic variation. Lines within the mapping population were placed in eight categories with respect to their various QTL combinations. Lines with no QTL were the most susceptible, whereas those with the Sumai 3-derived 3BS and 6BL QTL combined with the 2DS QTL from Y1193-6 were the most resistant. Though the 3BS and 6BL QTL are well-documented, the 2DS resistance QTL, which was contributed by the susceptible parent, confers increased susceptibility when derived from Sumai 3. In this study no new FHB QTL from Sumai 3 was discovered, but results suggest that Sumai 3 contains a QTL for susceptibility on chromosome arm 2DS. Selection against this QTL may potentially increase resistance levels among Sumai 3-derived populations.     

Mapping of QTL for resistance against Fusarium head blight in the winter wheat population Pelikan//Bussard/Ning8026

We report on the identification of FHB ( Fusarium head blight) resistance quantitative trait loci (QTL) of the donor 'G93010' (Bussard/Ning8026) in the background of elite breeding material adapted to the central European climate. With a multiple interval mapping method, two major resistance QTL were identified. Qfhs.lfl-7BS/5BL and Qfhs.lfl-6BS reduced FHB severity individually by 30% and 24%. The combination of both QTL decreased disease severity most effectively by about one half. Qfhs.lfl-6BS is most likely identical to Fhb2 , thus, the effectiveness of Fhb2 in central European breeding material has been validated. Qfhs.lfl-7BS/5BL overlapped with QTL for plant height and heading date. Nevertheless, the selection of lines combining a good FHB resistance level with an acceptable plant height was possible. As the donors of the QTL have probably not yet been utilized in European breeding material, we identified well-adapted lines of the mapping population as valuable donors for marker-assisted breeding programmes.     

Breeding for Fusarium head blight resistance in wheat—Progress and challenges

Fusarium head blight is among the most extensively studied fungal diseases of wheat and other small grain cereals due to its impact on yield and quality, but particularly due to its potential to produce mycotoxins, which are harmful to humans and animals. Since our last comprehensive review on QTL mapping and marker-assisted selection for FHB resistance in wheat in 2009, numerous studies have been conducted to identify, validate or fine-map resistance QTL. The main aim of this review is to update and summarize findings on FHB resistance breeding of wheat published during the last decade. Furthermore, we compiled a user-friendly table listing FHB resistance QTL data providing a valuable resource for further FHB resistance research. The role of morphological and phenological traits on FHB resistance and possible consequences for resistance breeding are discussed. This review concentrates current knowledge on breeding for FHB resistance and suggests strategies to enhance resistance by deploying molecular breeding methods, including marker-assisted and genomic selection.     

QTLs for Fusarium head blight response in a wheat DH population of Wangshuibai/Alondra‘s’

Summary A doubled haploid (DH) wheat population derived from the cross Wangshuibai/Alondra‘s’ was developed through chromosome doubling of haploids generated by anther culture of hybrids. Fusarium head blight (FHB) was evaluated for three years from 2001 to 2003 in Jianyang, Fujian Province, China, where epidemics of FHB have been consistently severe. After 307 pairs of simple sequence repeat (SSR) primers were screened, 110 pairs were polymorphic between Wangshuibai and Alondra`s’, and used to construct a genetic linkage map for detection of quantitative trait loci (QTLs). A stable QTL for low FHB severity was detected on chromosomes 3B over all three years, and QTLs on chromosomes 5B, 2D, and 7A were detected over two years. Additional QTLs on chromosomes 3A, 3D, 4B, 5A, 5D, 6B and 7B showed marginal significance in only one year. Six QTLs were detected when phenotypic data from three years were combined. In addition, significant additive-by-additive epistasis was detected for a QTL on 6A although its additive effect was not significant. Additive effects (A) and additive-by-additive epistasis (AA) explained a major portion of the phenotypic variation (76.5%) for FHB response. Xgwm533-3B and Xgwm335-5B were the closest markers to QTLs, and have potential to be used as selectable markers for marker-assisted selection (MAS) in wheat breeding programs.     

Effects of environment, disease progress, plant height and heading date on the detection of QTLs for resistance to Fusarium head blight in an European winter wheat cross

In order to characterise quantitative trait loci (QTLs) for Type I and Type II resistance against Fusarium head blight (FHB) in wheat, a population of recombinant inbred lines derived from the cross Cansas (moderately resistant)/Ritmo (susceptible) was evaluated in spray-inoculated field trials over three seasons. Map-based QTL analysis across environments revealed seven QTLs on chromosomes 1BS, 1DS, 3B, 3DL, 5BL, 7BS and 7AL (QFhs.whs-1B, QFhs.whs-1D, QFhs.whs-3B, QFhs.whs-3D, QFhs.whs-5B, QFhs.whs-7A, QFhs.whs-7B) associated with FHB resistance. They accounted for 56% of the phenotypic variance. QFhs.whs-1D primarily appeared to be involved in resistance to fungal penetration, whereas the other QTLs mainly contributed to resistance to fungal spread. FHB resistance was significantly correlated with plant height (PH) and heading date (HD). Including all single environments, corresponding overlaps of QTLs for FHB resistance and QTLs for PH/HD occurred at six loci, among them two consistently detected QTLs, QFhs.whs-5B and QFhs.whs-7A. When significant effects of PH and HD on FHB resistance were eliminated by covariance analysis, a second QTL analysis revealed possible escape mechanisms for the majority of the coincidental loci.     

Fusarium head blight resistance derived from Lophopyrum elongatum chromosome 7E and its augmentation with Fhb1 in wheat

The objective of this study was to assess the effectiveness of Fusarium head blight (FHB) resistance derived from wheatgrass Lophopyrum elongatum chromosome 7E and to determine whether this resistance can augment resistance in combination with other FHB resistance quantitative trait loci (QTL) or genes in wheat. The ‘Chinese Spring’–Lophopyrum elongatum disomic substitution line 7E(7B) was crossed to three wheat lines: ‘Ning 7840’, L3, and L4. F₂ populations were evaluated for type II resistance with the single‐floret inoculation method in the greenhouse. Simple sequence repeat markers associated with Fhb1 in ‘Ning 7840’ and L4 and markers located on chromosome 7E were genotyped in each population. Marker–trait association was analysed with one‐way or two‐way analysis of variance. The research showed that, in the three populations, the average number of diseased spikelets (NDS) in plants with chromosome 7E is 1.2, 3.1 and 3.2, vs. NDS of 3.3, 7.2 and 9.1 in plants without 7E, a reduction in NDS of 2.1, 4.1 and 5.9 in the respective populations. The QTL on 7E and the Fhb1 gene augment disease resistance when combined. The effect of the QTL on 7E was greater than that on 3BS in this experiment. Data also suggest that the FHB resistance gene derived from L. elongatum is located on the long arm of 7E.     

Variations for Fusarium head blight resistance associated with genomic diversity in different sources of the resistant wheat cultivar ‘Sumai 3’

Fusarium head blight (FHB), caused by Fusarium graminearum, is a serious disease of wheat (Triticum aestivum L.) associated with contamination by the mycotoxin deoxynivalenol (DON). The FHB-resistant wheat cultivar ‘Sumai 3’ has been used extensively around the world. The existence of variation in FHB resistance among ‘Sumai 3’ accessions has been discussed. In this study, genetic variation among ‘Sumai 3’ accessions collected from six countries were identified using SSR markers; our results demonstrate unique chromosome regions in Sumai 3-AUT and Sumai 3-JPN (‘Sumai 3’ accessions from Austria and Japan, respectively). Field evaluation indicated strong resistance to FHB in Sumai 3-AUT. The polymorphic rate (number of polymorphic markers/number of available markers × 100) based on a DArT array was 12.5% between the two ‘Sumai 3’ accessions. Genotyping for DNA markers flanking FHB-resistant quantitative trait loci (QTLs) revealed genetic variations for the QTL regions on 5AS and 2DS; however, no variation was observed for the QTL regions on 3BS and 6B. Thus, the variation in FHB resistance among ‘Sumai 3’ accessions in the field is due to genetic diversity.     

Identification of resistance gene analogue markers closely linked to wheat powdery mildew resistance gene Pm31

Specific oligonucleotide primers, designed for the sequences of known plant disease resistance genes, were used to amplify resistance gene analogues (RGAs) from wheat genomic DNA. This method was applied in a bulked segregant analysis to screen for the RGA markers linked to the powdery mildew resistance gene Pm31, introgressed into common wheat from wild emmer. Two RGA markers (RGA200 and RGA390) were found to be closely linked to Pm31 and completely co‐segregating with the marker allele of Xpsp3029 linked to Pm31, with a genetic distance of 0.6 cM. These two RGA markers were then integrated into the formerly established microsatellite map of Pm31 region. The result showed the effectiveness of the RGA approach for developing molecular markers linked to disease resistance genes and demonstrated the efficiency of denaturing polyacrylamide‐gel electrophoresis for detecting polymerase chain reaction polymorphism.