Peter Wehling

Ryd4 Hb : a novel resistance gene introgressed from Hordeum bulbosum into barley and conferring complete and dominant resistance to the barley yellow dwarf virus

Barley yellow dwarf virus (BYDV) causes high yield losses in most of the major cereal crops worldwide. A source of very effective resistance was detected within the tetraploid wild species of Hordeum bulbosum. Interspecific crosses between a resistant H. bulbosum accession and H. vulgare cv. ‘Igri’ were performed to transfer this resistance into cultivated barley. Backcrosses to H. vulgare resulted in offspring which carried a single subterminal introgression of H. bulbosum chromatin on barley chromosome 3HL and proved to be fully resistant to BYDV-PAV, as inferred by ELISA values of zero or close to zero and lack of BYDV symptoms. Genetic analysis indicated a dominant inheritance of the BYDV-PAV resistance factor, which we propose to denote Ryd4Hb. The identity and effect of Ryd4Hb are discussed in relation to other known genes for BYDV resistance or tolerance, as well as the relevance of this gene for resistance breeding in barley.

Development of conserved ortholog set markers linked to the restorer gene Rfp1 in rye

Restoration of male fertility is a prerequisite for hybrid rye breeding and currently the most straightforward approach to minimize ergot infection in hybrid rye varieties. Molecular markers are important tools for the efficient introgression and management of restorer genes like Rfp1 originating from unadapted genetic resources. Furthermore, closely linked markers flanking Rfp1 are indispensible for identifying and selecting individuals with haplotypes showing recombination between Rfp1 and other gene(s) that reside in close proximity and have a negative influence on yield. We identified orthologous gene sets in rice, Brachypodium, and Sorghum and used these gene models as templates to establish conserved ortholog set (COS) markers for the restorer gene Rfp1 on the long arm of rye chromosome 4R. The novel co-dominant markers delimit Rfp1 within a 0.7-cM interval and allow prediction of Rfp1 genotypes with a precision not feasible before. The COS markers enabled an alignment of the improved genetic map of rye chromosome 4R with wheat and barley maps and allowed identification of regions orthologous to Rfp1 in wheat and barley on the short arms of chromosomes 6D and 6H, respectively. Results obtained in this study revealed that micro-collinearity around the Rfp1 locus in rye is affected by rearrangements relative to other grass genomes. The impact of the novel COS markers for practical hybrid rye breeding is discussed.

GISH analysis of disomic Brassica napus-Crambe abyssinica chromosome addition lines produced by microspore culture from monosomic addition lines

Two Brassica napus--Crambe abyssinica monosomic addition lines (2n=39, AACC plus a single chromosome from C. abyssinca) were obtained from the F2 progeny of the asymmetric somatic hybrid. The alien chromosome from C. abyssinca in the addition line was clearly distinguished by genomic in situ hybridization (GISH). Twenty-seven microspore-derived plants from the addition lines were obtained. Fourteen seedlings were determined to be diploid plants (2n=38) arising from spontaneous chromosome doubling, while 13 seedlings were confirmed as haploid plants. Doubled haploid plants produced after treatment with colchicine and two disomic chromosome addition lines (2n=40, AACC plus a single pair of homologous chromosomes from C. abyssinca) could again be identified by GISH analysis. The lines are potentially useful for molecular genetic analysis of novel C. abyssinica genes or alleles contributing to traits relevant for oilseed rape (B. napus) breeding.

Characterization and mapping of LanrBo: a locus conferring anthracnose resistance in narrow-leafed lupin (Lupinus angustifolius L.)

Key messageA novel and highly effective source of anthracnose resistance in narrow-leafed lupin was identified. Resistance was shown to be governed by a single dominant locus. Molecular markers have been developed, which can be used for selecting resistant genotypes in lupin breeding.AbstractA screening for anthracnose resistance of a set of plant genetic resources of narrow-leafed lupin (Lupinus angustifolius L.) identified the breeding line Bo7212 as being highly resistant to anthracnose (Colletotrichum lupini). Segregation analysis indicated that the resistance of Bo7212 is inherited by a single dominant locus. The corresponding resistance gene was given the designation LanrBo. Previously published molecular anchor markers allowed us to locate LanrBo on linkage group NLL-11 of narrow-leafed lupin. Using information from RNAseq data obtained with inoculated resistant vs. susceptible lupin entries as well as EST-sequence information from the model genome Lotus japonicus, additional SNP and EST markers linked to LanrBo were derived. A bracket of two LanrBo-flanking markers allows for precise marker-assisted selection of the novel resistance gene in narrow-leafed lupin breeding programs.

Identification of transcriptome-based molecular markers linked to stem-rust resistance in perennial ryegrass

The project is dealing with the improvement of a universal pneumatic seeder which is suitable for sowing a wide range of different seeds in order to decrease particulate emissions of seed dressings. Aim of the project is to identify leakages in the pneumatic system in order to develop opportunities for the subsequent improvement of existing equipment to fulfill the high demands of user and environmental protection. Pneumatic seeders are characterized by a central, funnelshaped hopper. The batch feeder being an airlock and dosing feeder is located in the outlet of the seeder. The metered seed is fed into the air stream and transported to the sowing distributor by a conveying air stream.Due to climatic change, phenology traits are becoming increasingly important in grapevine breeding, since a premature flowering and ripening time could be observed for grapevine in the last decades. However, knowledge about these traits is still limited as they are genetically very complex and highly influenced by environmental factors. The analysis of the genetic basis of flowering time therefore will enable the development of tightly linked molecular markers useful for markerassisted selection of especially late flowering breeding lines.One recently occurred invasive insect pest has caught the attention for investigating biological control mechanisms and systems: The spotted wing drosophila (SWD, Drosophila suzukii Matsumura) is endemic in East China and Japan but has been introduced to the western hemisphere about 10 years ago and has been found in Europe since 2009. Nowadays, it has emerged to one of the most harmful pests to commercially grown fruit plants like stone fruits and nearly all kind of berries while it prefers ripe and overripe fruits. Our intention is to investigate the possible usage of natural antagonists for biological control. Therefore, we examine the natural load of parasites and pathogens (i.e. fungi, bacteria, viruses, microsporidia and protista) in fruit flies, isolate them and re-infect lab populations of D. suzukii for investigating the antagonistic potential. Furthermore, we will integrate the fruit pest codling moth (Cydia pomonella), which is an ongoing problem in apple orchards also because the pest develops resistance against commercially available insecticides. The long-term aim is to establish a stable system for pathogen detection that can be used for rapid identification of microbial antagonists in natural populations.Two main problems have to be considered in the development of control agents against the Fire Blight pathogen Erwinia amylovora: First, the ability of exponential growth leads to high cell densities in a short amount of time. Second, the most critical phase of Fire Blight infection occurs during blossoming, when the pathogen is transported to open flowers by various insects. To prevent infection, it is important to avoid invasion inside the plants tissue by interfering with growth of E. amylovora cells.The entomopathogenic fungus Isaria fumosorosea, formerly known as Paecilomyces fumosoroseus, has got a relatively wide host range. Within the scope of the EU project BIOCOMES investigations were done to validate the use of I. fumosorosea as a BCA against several pest insects. Under laboratory conditions it could be shown that I. fumosorosea seems to be a suitable BCA against Bemisia tabaci (silverleaf whitefly) and Spodoptera exigua (beet armyworm).Since the last two decades a number of fingerprinting methods have been developed to analyze microbial communities and their dynamics, including Terminal Restriction Fragment Length Polymorphism (T-RFLP), Length Heterogeneity-Polymerase Chain Reaction (LHPCR) and Automated Ribosomal Intergenic Spacer Analysis (ARISA). Because the latter provides a quick and cheap way together with high accuracy, we have chosen this method to investigate the fungal communities on grapevine, wood, leaves and berries.Saoussen Ben Tiba, Andreas Larem, Eva Fritsch, Karin Undorf-Spahn, Asma Laarif, Sami Fattouch, Johannes A. Jehle 1 Julius Kuhn-Institut, Institute for Biological Control, Darmstadt, Germany 2 Regional Center for Agriculture and Biological Agriculture, Chott Meriem, Tunisia 3 National Institute for applied technological Science Tunis (INSAT), Carthage University, Tunisia Email of corresponding author: saoussen.ben.tiba@jki.bund.deOne promising approach to a more environmentally friendly viticulture is growing fungus resistant cultivars with the novel cultivation method of the minimal pruning of trellis trained grapevines (MPTS). This practice reduces the tremendous amounts of fungicides needed to protect traditional cultivars and is expected to increase biodiversity compared to vineyards with traditional trellis trained grapevines (TS).Meiosis as the specialized cell division of sexual reproduction plays a crucial role in the exchange and reorganization of genetic material between two individuals by dividing the chromosome set in half and forming gametes. Even though in the last years major findings in the field of meiosis have been achieved, especially in plants, some key questions remain concealed. For a proper meiosis the initiation of double strand breaks (DSBs) during early prophase I is essential. Without DSBs no physical connection can occur between homologous chromosomes and recombination, pairing, and crossing over are excluded. So far in all analyzed eukaryotes SPO11, a meiosis specific transesterase, is the key enzyme inducing DSBs. But other than in animals and fungi where a single SPO11 is sufficient, plants need at least two different SPO11, referred to as SPO11-1 and SPO11-2, for proper meiosis. In Arabidopsis thaliana both have crucial functions and are essential in a functional form for the induction of meiotic DSBs as single knock out mutants are leading to near sterility by random chromosome distribution. Despite the same function of the homologs SPO111 and -2, the identity between both proteins is quite low. Homology of the orthologous SPO11 from different organisms is much higher. By exchanging SPO11-1 and -2 in Arabidopsis by their orthologs from various organisms we could demonstrate a species specific function of each SPO11, as a functional complementation of sterility could only be achieved with SPO11 from closely related species from the Brassicaceae. By exchanging non conserved regions between SPO11-1 and -2 of Arabidopsis we additionally could show a sequence specific function for each SPO11, as a functional rescue could not be achieved with all chosen regions. Interestingly, we could reveal a specific pattern of aberrant spliced isoforms for each SPO11 which are also sequence as well as species specific. By producing antibodies against AthSPO11-1 and -2 we were able to analyze for the first time the binding of SPO11-2 onto the DNA and perform co-immunolocalization studies with SPO11-1 and -2.European Stone Fruit Yellows (ESFY) is one of the most serious diseases in European fruit production. Infected Prunus cultivars yield poorly and lead to high economic losses. ESFY is caused by a specialized bacterium located in the phloem tissue of Prunus ssp., the Phytoplasma ‘Candidatus Phytoplasma prunorum’. It is spread by the phloemfeeding plum psyllid (Cacopsylla pruni) which acquires the bacterium by feeding on infected plants and is able to transmit it to healthy plants.Leaf rust caused by Puccinia triticina can cause yield losses up to 60 % and is the most common rust disease of wheat in the world. Vertical leaf rust resistance genes (Lr-genes) have been introduced in cultivars. Many of these resistances are broken down by virulent pathotypes. Horizontal resistances which are independent from races of a pathogen are known but show a quantitative characteristic which is carried by a few cultivars.

The Secondary Gene Pool of Barley (Hordeum bulbosum): Gene Introgression and Homoeologous Recombination

While the primary gene pool with the two subspecies of Hordeum vulgare subsp. vulgare and H. vulgare subsp. spontaneum has long been utilised as a rich and easy-to-use gene resource for barley breeding, the secondary gene pool proved more difficult to be tapped for novel gene variants. During the past 20 years, though, ample evidence has been accumulated that the secondary gene pool of barley also presents a rich resource of trait genes which are of potential interest to breeders. To date, most disease resistances have been in the focus of interest and were introgressed from Hordeum bulbosum into barley, among them resistances to a variety of pathogenic fungi as well as viruses. The use of molecular techniques such as in situ hybridisation and molecular markers has provided a deeper insight into the chromosomal locations of introgressed segments, their sizes and recombination activities against a barley-genetic background and has paved the way for a deliberate selection of recombinant offspring which can be used in plant breeding programmes. Thus, it can be stated that the secondary gene pool of barley has been opened up as a novel genetic resource in barley breeding.