Development of a set of highly polymorphic genomic microsatellites (gSSRs) in Sitka spruce (Picea sitchensis (Bong.) Carr.)

Robust, polymorphic microsatellite DNA markers (simple sequence repeats—SSRs) are valuable tools for a range of tree conservation and breeding applications. SSRs are routinely used in the study of population genetic structure and diversity, pedigree reconstruction and genetic linkage mapping. Their abundance in the genome, co-dominant inheritance and potential for cross-species amplification make microsatellites highly prized markers. This paper characterises 22 novel genomic polymorphic microsatellite loci for Sitka spruce (Picea sitchensis (Bong.) Carr.). Amplification of DNA from Sitka spruce material was carried out both with a set of unrelated trees to obtain diversity statistics for each locus, and with the progeny of a full-sib family to test simple Mendelian inheritance. Observed heterozygosity ranged from 0.38 to 0.91 and allele number per locus ranged from 6 to 21, with a mean of 12.2. In addition, the primer pairs were tested with DNA from Norway spruce (P. abies) and white spruce (P. glauca) to investigate their potential for cross-species amplification and ten loci amplified in all three species. The results from these genomic microsatellites are compared to data generated from microsatellites derived from Picea EST libraries. In summary, this novel, highly polymorphic markers represent a significant addition to the rapidly expanding Picea genomics tool-box. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Associations of genes encoding allozymes peroxidase and superoxide dismutase in poplar and spruce species

Summary Isozymes of peroxidase (PER) and superoxide dismutase (SOD) were analyzed in vegetative buds or very young leaves of seven species and two interspecific hybrids of Populus, in progenies of seven controlled crosses of three Populus species, and in needles of five Picea species and one putative hybrid. One to three PER, and one or two SOD zones of activity were observed. Electrophoretic mobility (EM) and banding phenotypes of isozymes of one PER locus were identical to those of one SOD locus in vegetative buds of five Populus species and hybrid. In leaves of the four Populus species and hybrid and progenies of controlled crosses, EM and phenotypes of isozymes of two PER loci were identical to those of two SOD loci. In Picea species, EM of isozymes of the only SOD locus was somewhat similar but not identical to that of one PER locus, and isozyme phenotypes of all individuals at the SOD locus were not identical to those at a PER locus. Chi-square tests verified the single-gene Mendelian control of the segregating allozyme variants at each of Per-L1 and Sod-1 in the three Populus species. The results of joint two-locus segregation tests indicated a very tight linkage and no recombination between Per-L1 and Sod-1 in three Populus species. Genes coding for isozymes of one or two PER loci are either presumably the same as, or very tightly linked to, the genes coding for isozymes of one or two SOD loci in the Populus species.     

Is there selection by species diversity in <Emphasis Type="Italic">Picea</Emphasis> <Emphasis Type="Italic">abies</Emphasis> L.?

In view of the progressive destruction of the biosphere, biodiversity research plays an important role in the search for factors affecting species diversity and in the analysis of the effects of species diversity on ecosystems. However, research into how species diversity and composition are related to genetic structures is still at the beginning. In this study, we combined population genomics, new correlative approaches, and randomization permutation methods to identify adaptive genetic differentiation in populations of the Norway spruce Picea abies L. that display different levels of species diversity. We detected a significant positive large covariation (C) between species diversity (ν _a ) and genotype frequency at a gene locus, resulting from differential selection by species diversity or by environmental factors. The results may contribute to understand the interplay between ecological and evolutionary processes in determining community structure and dynamics.     

Comparative genome mapping among Picea glauca, P. mariana × P. rubens and P. abies, and correspondence with other Pinaceae

A composite linkage map was constructed from four individual maps for the conifer Picea glauca (Moench) Voss, from anonymous and gene-specific markfers (714 AFLPs, 38 SSRs, and 53 ESTPs). A total of 12 linkage groups were delineated with an average marker density of 2.7 cM. Macro-synteny and macro-colinearity comparisons with two other composite linkage maps developed for the species complex P. mariana (Mill.) B.S.P. × P. rubens Sarg., and for P. abies (L.) Karst. revealed an identical number of linkage groups and a remarkable conservation of the gene content and gene order of linkage groups over the million years since the split between these taxa. Identical gene order among taxa was observed for 10 of the 12 assembled composite linkage groups. The discovery of one breakdown in synteny between P. glauca and the other two taxa indicated the occurrence of an inter-chromosomal rearrangement involving an insertional translocation. Analysis of marker colinearity also revealed a putative segmental duplication. The combined information from these three Picea genomes validated and improved large-scale genome comparisons at the inter-generic level in the family Pinaceae by allowing for the identification of 11 homoeologous linkage groups between Picea and Pinus, and nine such groups between Picea and Pseudotsuga menziesii. Notably, the analysis of synteny among the three genera revealed a putative case of chromosomal fission and an inter-chromosomal rearrangement in the genome of P. menziesii. Both of these changes are inter-connected, indicating much instability in this part of the P. menziesii genome. Overall, the macro-structure of the Pinaceae genome was well conserved, which is notable given the Cretaceous origin of its main lineages.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.Her Majesty the Queen in Right of Canada.     

沙地云杉与其近缘种间的GISH分析

以沙地云杉(Picea mongolica(H.Q.Wu)W.D.Xu)、白杄(P.meyeri Rehd.et Wils.)、红皮云杉(P.koraiensis Nakai)3种云杉属植物为材料,利用基因组原位杂交技术(GISH),用白杄和红皮云杉基因组DNA分别作探针与沙地云杉中期染色体进行杂交,分析3种云杉的亲缘关系,旨在进一步探讨沙地云杉的起源。结果表明:(1)3种云杉的染色体数目均为2n=24,核型类型为1A,大部分染色体为亚中部着丝粒;白杄和红皮云杉核型不对称系数分别为57.78%、57.64%,小于沙地云杉(58.75%)。(2)以白杄基因组DNA为探针时,在沙地云杉14条染色体上有明显杂交信号,信号位点主要位于着丝粒区、次缢痕处和短臂部位;以红皮云杉DNA为探针时,12条染色体上有明显杂交信号,主要位于着丝粒区、次缢痕处和长臂上,杂交信号分布范围和强度明显弱于白杄。研究认为,沙地云杉与白杄的亲缘关系较近,而与红皮云杉较远,该研究首次阐明沙地云杉非起源于白杄和红皮云杉的种间杂交。     

Length variation in the internal transcribed spacers of ribosomal DNA in Picea abies and related species

The structure and variation of nuclear ribosomal DNA (rDNA) units of Picea abies, (L.) Karst. was studied by restriction mapping and Southern hybridization. Conspicuous length variation was found in the internal transcribed spacer (ITS) region of P. abies, although the length of this region is highly conserved both within and among most of the plant species. Two types of ITS variants (A and B), displaying a size difference of 0.5 kb in the ITS2 region, were present within individuals of P. abies from Sweden, Central Europe and Siberia. A preliminary survey of 14 additional Eurasian and North American species of Picea suggested that length variation in the ITS region is widespread in this genus. Alltogether three length variants (A, B and C) were identified. Within individuals of eight Picea species, two length variants were present within the genome (combinations of A and B variants in P. glehnii, P. maximowiczii, P. omorika, P. polita and P. sitchensis and variants B and C in P. jezoensis, P. likiangensis and P. spinulosa). Within individuals from five species, however only one rDNA variant was present in their genome (variant A in P. aurantiaca, P. engelmannii, P. glauca, P. koraiensis and P. koyamai; variant B in P. bicolor). The ITS length variation will be useful as a molecular marker in evolutionary studies of the Picea species complex, whose phylogeny is controversial. The presence of intraindividual variation in, and shared polymorphism of the, ITS length variants raises questions about the occurrence of interspecific hybridization during the evolutionary history of Picea.     

Stand structure and regeneration in a Kamchatka mixed boreal forest

Abstract. A 1‐ha plot was established in a Betula platyphylla‐Picea ajanensis mixed boreal forest in the central Kamchatka peninsula in Russia to investigate stand structure and regeneration. This forest was relatively sparse; total density and stand basal area were 1071/ha and 25.8 m²/ha, respectively, for trees > 2.0 cm in trunk diameter at breast height (DBH). 25% of Betula regenerated by sprouting, and its frequency distribution of DBH had a reverse J‐shaped pattern. In contrast, Picea had a bimodal distribution. The growth rates of both species were high, reaching 20 m in ca. 120 yr. The two species had clumped distributions, especially for saplings. Betula saplings were not distributed in canopy gaps. Small Picea saplings were distributed irrespective of the presence/absence of gaps, while larger saplings aggregated in gaps. At the examined spatial scales (6.25–400 m²) the spatial distribution of Betula saplings was positively correlated with living Betula canopy trees and negatively with dead Picea canopy trees. This suggests that Betula saplings regenerated under the crowns of Betula canopy trees and did not invade the gaps created by Picea canopy trees. The spatial distribution of Picea saplings was negatively correlated with living and dead Betula canopy trees and positively with dead Picea canopy trees. Most small Picea seedlings were distributed under the crowns of Picea trees but not under the crowns of Betula trees or in gaps. This suggests that Picea seedlings establish under the crowns of Picea canopy trees and can grow to large sizes after the death of overhead Picea canopy trees. Evidence of competitive exclusion between the two species was not found. At a 20 m × 20 m scale both skewness and the coefficient of variation of DBH frequency distribution of Picea decreased with an increase in total basal area of Picea while those of Betula were unchanged irrespective of the increase in total basal area of Betula. This indicates that the size structure of Picea is more variable with stand development than that of Betula on a small scale. This study suggests that Betula regenerates continuously by sprouting and Picea regenerates discontinuously after gap formation and that the species do not exclude each other.     

Regeneration of transgenic Picea glauca, P. Mariana, and P. abies after cocultivation of embryogenic tissue with Agrobacterium tumefaciens

Summary Transgenic plants of three Picea species were produced after coculture of embryogenic tissue with the disarmed strain of Agrobacterium tumefaciens C58/pMP90/pBIV10 and selection on medium containing kanamycin. In addition to the nptII selectable gene (conferring resistance to kanamycin), the vector carried the uidA (β-glucuronidase) marker gene. Transformation frequencies were dependent on the species, genotype, and post-cocultivation procedure. Of the three species tested, P. mariana was transformed at the highest frequency, followed by P. glauca and P. abies. The transgenic state of the embryogenic tissue was initially, confirmed by histochemical β-glucuronidase (GUS) assay followed by Southern hybridization. One to over five copies of T-DNA were detected in various transgenic lines analyzed. Transgenic plants were regenerated for all species using modified protocols for maturation and germination of somatic embryos.     

Genetic analysis and fine mapping of a rice brown planthopper (Nilaparvata lugens Stål) resistance gene bph19(t)

Genetic analysis and fine mapping of a resistance gene against brown planthopper (BPH) biotype 2 in rice was performed using two F₂ populations derived from two crosses between a resistant indica cultivar (cv.), AS20-1, and two susceptible japonica cvs., Aichi Asahi and Lijiangxintuanheigu. Insect resistance was evaluated using F₁ plants and the two F₂ populations. The results showed that a single recessive gene, tentatively designated as bph19(t), conditioned the resistance in AS20-1. A linkage analysis, mainly employing microsatellite markers, was carried out in the two F₂ populations through bulked segregant analysis and recessive class analysis (RCA), in combination with bioinformatics analysis (BIA). The resistance gene locus bph19(t) was finely mapped to a region of about 1.0 cM on the short arm of chromosome 3, flanked by markers RM6308 and RM3134, where one known marker RM1022, and four new markers, b1, b2, b3 and b4, developed in the present study were co-segregating with the locus. To physically map this locus, the bph19(t)-linked markers were landed on bacterial artificial chromosome or P1 artificial chromosome clones of the reference cv., Nipponbare, released by the International Rice Genome Sequencing Project. Sequence information of these clones was used to construct a physical map of the bph19(t) locus, in silico, by BIA. The bph19(t) locus was physically defined to an interval of about 60 kb. The detailed genetic and physical maps of the bph19(t) locus will facilitate marker-assisted gene pyramiding and cloning.     

Isolation and characterization of EST‐derived microsatellite loci from the fungal wheat pathogen Phaeosphaeria nodorum

Eleven polymorphic microsatellite loci and one minisatellite locus originating from expressed sequence tag (EST) libraries of Phaeosphaeria (syn. Stagonospora) nodorum were isolated and characterized. The satellite markers were used to genotype isolates from field populations collected in China, North America and South Africa. The number of alleles per locus ranged from two to 15. Genotype diversity ranged from 87.5 to 95.3 and gene diversity from 0.1 to 0.8. The variable levels of polymorphism within and among populations of P. nodorum renders these 12 satellite loci ideal markers for population genetic analysis of P. nodorum.     

Genetic risk factors for nonsyndromic cleft lip with or without cleft palate in a Mesoamerican population: Evidence for IRF6 and variants at 8q24 and 10q25

INTRODUCTION: Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common of all birth defects. NSCL/P has a multifactorial etiology that includes both genetic and environmental factors. The IRF6 gene and three further susceptibility loci at 8q24, 10q25, and 17q22, which were identified by a recent genome‐wide association scan (GWAS), are confirmed genetic risk factors for NSCL/P in patients of European descent. METHODS: A case‐control association study was performed to investigate whether these four risk loci contribute to NSCL/P in a Mesoamerican population using four single nucleotide polymorphisms to represent IRF6 and the three novel susceptibility loci. A total of 149 NSCL/P patients and 303 controls of Mayan origin were included. RESULTS: Single marker analysis revealed a significant association between NSCL/P and risk variants in IRF6 and the 8q24 and 10q25 loci. In contrast to previous findings, the association at the 8q24 locus was driven solely by homozygote carriers of the risk allele. This suggests that this locus might act in a recessive manner in the Mayan population. No evidence for association was found at the 17q22 locus. This may have been attributable to the limited power of the sample. CONCLUSION: These results suggest that IRF6 and the 10q25 and 8q24 loci confer a risk for the development of NSCL/P in persons of Mayan origin. Birth Defects Research (Part A), 2010. © 2010 Wiley‐Liss, Inc.     

Regeneration and coexistence of two subalpine conifer species in relation to dwarf bamboo in the understorey

Abstract. Microhabitats for seedling establishment and gap regeneration in subalpine forests of northern Japan were studied for two conifers, Abies sachalinensis and Picea glehnii. The abundance of understorey dwarf bamboo (Sasa spp.) was different for the four plots examined. Two types of micro-habitats were recognized for the two conifers: ground and elevated woody substrates (fallen logs and buttresses). Picea regenerated mostly on elevated sites, while Abies regenerated on both ground and elevated sites. The densities of Picea were independent of those of Sasa, but Abies densities decreased with increasing abundance of Sasa because Sasa reduced regeneration on the ground. Density of Abies on elevated sites was higher than that of Picea, irrespective of Sasa and of the density of adult trees. There was no significant difference in growth in sapling trunk height between the two conifers, but Picea grew more slowly under the canopy than Abies and was aggregated into gaps. Thus, in forests with less Sasa, the recruitment capacity of Abies was greater than that of Picea. The long life span of Picea compensated for its low density on elevated sites. Examination of a dynamic system model showed that Picea was excluded by Abies in forests without Sasa because regeneration on the ground is more advantageous than on elevated sites, but the two conifers could coexist in forests with Sasa because of the increased relative success of regeneration on elevated sites by Picea saplings.     

Range-wide genetic structure in a north-east Asian spruce (Picea jezoensis) determined using nuclear microsatellite markers

Aim We used microsatellite markers to determine the range‐wide genetic structure of Picea jezoensis and to test the hypothesis that the past population history of this widespread cold‐temperate spruce has resulted in a low level of genetic variation and in imprints of inbreeding and bottlenecks in isolated marginal populations. Location The natural range of the three infraspecific taxa of P. jezoensis throughout north‐east Asia, including isolated marginal populations. Methods We analysed a total of 990 individuals across 33 natural populations using four nuclear microsatellite loci. Population genetic structure was assessed by analysing genetic diversity indices for each population, examining clustering (model‐based and distance‐based) among populations, evaluating signals of recent bottlenecks, and testing for isolation by distance (IBD). Results The 33 populations were clustered into five groups. The isolated marginal groups of populations (in Kamchatka, Kii in Japan and South Korea) exhibited low levels of allelic richness and gene diversity and a complete or almost complete loss of rare alleles. A recent bottleneck was detected in the populations in Hokkaido across to mid‐Sakhalin. The IBD analysis revealed that genetic divergence between populations was higher for populations separated by straits. Main conclusions Picea jezoensis showed a higher level of genetic differentiation among populations (F_ST = 0.101) than that observed in the genus Picea in general. This might be attributable to the fact that historically the straits around Japan acted as barriers to the movement of seeds and pollen. The low levels of genetic diversity in the isolated marginal population groups may reflect genetic drift that has occurred after isolation. Evidence of a significant bottleneck between the Hokkaido and mid‐Sakhalin populations implies that the cold, dry climate in the late Pleistocene resulted in the decline and contraction of populations, and that there was a subsequent expansion followed by a founder effect when conditions improved. The high polymorphism observed in P. jezoensis nuclear microsatellites revealed cryptic genetic structure that organellar DNA markers failed to identify in a previous study.     

Variation at the common polysaccharide antigen locus drives lipopolysaccharide diversity within the Pseudomonas syringae species complex

The common polysaccharide antigen (CPA) of the lipopolysaccharide (LPS) from Pseudomonas syringae is highly variable, but the genetic basis for this is poorly understood. We have characterized the CPA locus from P. syringae pv. actinidiae (Psa). This locus has genes for l - and d -rhamnose biosynthesis and an operon coding for ABC transporter subunits, a bifunctional glycosyltransferase and an o -methyltransferase. This operon is predicted to have a role in the transport, elongation and termination of the CPA oligosaccharide and is referred to as the TET operon. Two alleles of the TET operon were present in different biovars (BV) of Psa and lineages of the closely related pathovar P. syringae pv. actinidifoliorum. This allelic variation was reflected in the electrophoretic properties of purified LPS from the different isolates. Gene knockout of the TET operon allele from BV1 and replacement with that from BV3, demonstrated the link between the genetic locus and the biochemical properties of the LPS molecules in Psa. Sequence analysis of the TET operon from a range of P. syringae and P. viridiflava isolates displayed a phylogenetic history incongruent with core gene phylogeny but correlates with previously reported tailocin sensitivity, suggesting a functional relationship between LPS structure and tailocin susceptibility.     

RAPD and Allozyme Analysis of Genetic Diversity in Panax ginseng C.A. Meyer and P. quinquefolius L.

Inter- and intraspecific variation of two ginseng species Panax ginseng and P. quinquefolius was estimated by studying 159 RAPD and 39 allozyme loci. Parameters of polymorphism and genetic diversity were determined and a tree was constructed to characterize the differences between individual plants, samples, and species. Genetic variation in P. ginseng proved to be lower than in P. quinquefolius. Gene diversity in the total P. ginseng sample was comparable with the mean expected heterozygosity of herbaceous plants. This suggests that wild P. ginseng plants in various areas of the currently fragmented natural habitat and cultivated plants of different origin have retained a significant proportion of their gene pool. The mean heterozygosity calculated per polymorphic locus for the RAPD phenotypes is similar to that of the allozyme loci and may be helpful in estimating gene diversity in populations of rare and endangered plant species.     

Recovery of Abies alba and Picea abies saplings to browsing and frost damage depends on seed source

The density of wild ungulates has increased in the last century, and browsing has become a major driver of forest succession in the northern hemisphere. In addition, tree species are expected to respond differently to future climate conditions, especially an increased frequency of late frost events. The aim of this study was to analyze the influence of intraspecific genetic variation on the recovery of two tree species to frost and browsing. An experiment with saplings from 90 Abies alba and 72 Picea abies seed sources was conducted. Five‐year‐old saplings were clipped at three intensities before budburst in spring. Growth (height, diameter, leader shoot length, and biomass) and quality (e.g. stem form, multistemming, reaction type) were assessed before and 1–2 years after clipping or 3–4 years after natural frost events, and provenance differences were related to environmental differences at the seed source. For Abies, frost and clipping resulted in reduced height growth in the first year after the stress and reduced height for two (clipping) to four (frost) vegetation periods. Sapling biomass, diameter increment, and quality decreased after heavy clipping. For Picea, which grew twice as fast as Abies, such effects were only found after frost damage. Population differences were significant for both species for all investigated growth traits and for Picea also for some quality variables. The “reaction type” after browsing (e.g. new shoot, existing twig bending upward) seems to be species specific and independent of seed source. In contrast, the time lag between clipping and formation of a clear new leader shoot increased for Abieswith lower temperatures at the seed source. Lowland populations with warmer climates grew faster, and for Picea also qualitatively better, and recovered faster from leader shoot loss (Abies) or reacted at the uppermost meristem (Picea). Thus, the investigated stressors increased the existing differences among populations.     

Comparative studies on the mycorrhization of Larix decidua and Picea abies by Suillus grevillei

Summary Mycorrhization of Picea abies has been achieved, for the first time, with six strains of Suillus grevillei by a new culture method, using activated charcoal paper and liquid medium as a substrate. Mycorrhization of P. abies and Larix decidua was compared, and the process was found to be significantly different in the two tree species. S. grevillei is not incompatible with P. abies, but it forms mycorrhizae more readily with L. decidua. Hyphal growth was clearly stimulated on the surface of roots of Larix but retarded on Picea. A well organized Hartig net was formed with both tree species, but wall protuberances were frequently observed on the outer cell walls of Picea cortex cells when the Hartig net was not fully developed. No conspicuous cell wall reactions occurred in Larix roots. Cell wall protuberances may be comparable to those in transfer cells and are interpreted as an alternative to Hartig net development. Anatomical differences between roots of Larix and Picea, and physiologically active substances such as recognition factors on the root surfaces, are discussed with respect to their responsibility for the different reactions of S. grevillei.     

Effects of genetic variability of the dairy goat growth hormone releasing hormone receptor (<Emphasis Type="Italic">GHRHR</Emphasis>) gene on growth traits

Growth hormone-releasing hormone receptor (GHRHR) plays a critical role in growth hormone (GH) synthesis, release and regulation of pituitary somatotroph expansion in vertebrates. The objective of this study was to investigate variations in goat GHRHR gene and their associations with growth traits in 668 dairy goats. The results showed four novel single nucleotide polymorphisms (SNPs): NC_007302:g.5203C>T, 7307C>G, 9583G>A and 9668A>C. In detail, the novel SNP C>T in the 5203rd nucleotide identified a missense mutation: CCC (Pro)>TCC (Phe) at position 116aa of the goat GHRHR (423aa). Besides, 9583G>A and 9668A>C polymorphism were in complete linkage disequilibrium. The genetic diversity analysis revealed that the Guanzhong dairy goat possessed intermediate genetic diversity in P3 and P7 loci, and the Xinong Sannen dairy goat belonged to poor genetic diversity in P4 locus. Significant associations between the genotypes of P3 locus and body length, body height and chest circumference was observed in Guanzhong goat (P < 0.05). However, in Xinong saanen population, significant statistical difference was only found in body height and body length (P < 0.05). In P4 and P7 loci, no significant associations were detected between any variant sites and body length, body height and chest circumference, as well as for the milk traits (P > 0.05). These results strongly suggested that the goat GHRHR gene is a candidate gene that influences growth traits in dairy goat.     

Genetic mapping of the <Emphasis Type="Italic">Leptosphaeria maculans</Emphasis> avirulence gene corresponding to the <Emphasis Type="Italic">LepR1</Emphasis> resistance gene of <Emphasis Type="Italic">Brassica napus</Emphasis>

AvrLepR1 of the fungal pathogen Leptosphaeria maculans is the avirulence gene that corresponds to Brassica LepR1, a plant gene controlling dominant, race-specific resistance to this pathogen. An in vitro cross between the virulent L. maculans isolate, 87-41, and the avirulent isolate, 99-56, was performed in order to map the AvrLepR1 gene. The disease reactions of the 94 of the resulting F₁ progenies were tested on the canola line ddm-12-6s-1, which carries LepR1. There were 44 avirulent progenies and 50 virulent progenies suggesting a 1:1 segregation ratio and that the avirulence of 99-56 on ddm-12-6s-1 is controlled by a single gene. Tetrad analysis also indicated a 1:1 segregation ratio. The AvrLepR1 gene was positioned on a genetic map of L. maculans relative to 259 sequence-related amplified polymorphism (SRAP) markers, two cloned avirulence genes (AvrLm1 and AvrLm4-7) and the mating type locus (MAT1). The genetic map consisted of 36 linkage groups, ranging in size from 13.1 to 163.7 cM, and spanned a total of 2,076.4 cM. The AvrLepR1 locus was mapped to linkage group 4, in the 13.1 cM interval flanked by the SRAP markers SBG49-110 and FT161-223. The AvrLm4-7 locus was also positioned on linkage group 4, close to but distinct from the AvrLepR1 locus, in the 5.4 cM interval flanked by FT161-223 and P1314-300. This work will make possible the further characterization and map-based cloning of AvrLepR1. A combination of genetic mapping and pathogenicity tests demonstrated that AvrLepR1 is different from each of the L. maculans avirulence genes that have been characterized previously.