Brigitte Ruge-Wehling

Protein crop plants such as soybean and lupin are attracting increasing attention because of their potential use as forage, green manure, or for the production of oil and protein for human consumption. Whereas soybean production only recently gained more importance in Germany and within the whole EU in frame of protein strategies, lupin production is already well-established in Germany. The cultivation of lupins is impeded by the hemibiotrophic ascomycete Colletotrichum lupini, the causal agent of anthracnose disease. Worldwide, soybean is also a host for a variety of Colletotrichum species, but so far, this seems to not be the case in Germany. Cross-virulence between lupin- and soybean-infecting isolates is a potential threat, especially considering the overlap of possible soybean and lupin growing areas in Germany. To address this question, we systematically investigated the interaction of different Colletotrichum species isolated from soybean in Brazil on German soybean and lupin plant cultivars. Conversely, we tested the interaction of a German field isolate of C. lupini with soybean. Under controlled conditions, Colletotrichum species from soybean and lupin were able to cross-infect the other host plant with varying degrees of virulence, thus underpinning the potential risk of increased anthracnose diseases in the future. Interestingly, we observed a pronounced plant growth-promoting effect for some host–pathogen combinations, which might open the route to the use of beneficial biological agents in lupin and soybean production.

Protein crop plants such as soybean and lupin attract increasing attention because of their potential use as forage, green manure or for the production of oil and protein for human consumption. While soybean production only recently gained more importance in Germany and within the whole EU in frame of protein strategies, lupin production already is well established in Germany. The cultivation of lupins is impeded by the hemibiotrophic ascomycete Colletotrichum lupini , the causing agent of anthracnose disease. Worldwide, soybean is also a host for a variety of Colletotrichum species, but so far this seems not to be the case in Germany. Cross-virulence between lupin and soybean infecting isolates is a potential threat, especially taking into consideration the overlap of possible soybean and lupine growing areas in Germany. To address this question, we systematically investigated the interaction of different Colletotrichum species isolated from soybean in Brazil on actual German soybean and lupin plant cultivars. Conversely, we tested the interaction of a German field isolate of C. lupini with soybean. Under controlled conditions, Colletotrichum species from soybean and lupin were able to cross-infect the other host plant with varying degrees of virulence, thus underpinning the potential risk of increased anthracnose diseases in the future. Interestingly, we observed a pronounced plant growth-promoting effect for some host-pathogen combinations which might open the route to the use of beneficial biological agents in lupine and soybean production.

Powdery mildew caused byBlumeria graminisf.sp.hordei (Bgh)is one of the main foliar diseases in barley (Hordeum vulgareL.;Hv). Naturally occurring resistance genes used in barley breeding are a cost effective and environmentally sustainable strategy to minimize the impact of pathogens, however, the primary gene pool ofH. vulgarecontains limited diversity owing to recent domestication bottlenecks. To ensure durable resistance against this pathogen, more genes are required that could be unraveled by investigation of secondary barley gene-pool. A large set ofHordeum bulbosum(Hb) introgression lines (ILs) harboring a diverse set of desirable resistance traits have been developed and are being routinely used as source of novel diversity in gene mapping studies. Nevertheless, this strategy is often compromised by a lack of recombination between the introgressed fragment and the orthologous chromosome of the barley genome. In this study, we fine-mapped aHbgene conferring resistance to barley powdery mildew. The initial genotyping of twoHbILs mapping populations with differently sized 2HS introgressions revealed severely reduced interspecific recombination in the region of the introgressed segment, preventing precise localization of the gene. To overcome this difficulty, we developed an alternative strategy, exploiting intraspecific recombination by crossing twoHv/HbILs with collinearHbintrogressions, one of which carries a powdery mildew resistance gene, while the other doesn’t. The intraspecific recombination rate in theHb-introgressed fragment of 2HS was approximately 20 times higher than it was in the initial simple ILs mapping populations. Using high-throughput genotyping-by-sequencing (GBS), we allocated the resistance gene to a 1.4 Mb interval, based on an estimate using theHvgenome as reference, in populations of only 103 and 146 individuals respectively, similar to what is expected at this locus in barley. The most likely candidate resistance gene within this interval encodes a legume-type lectin-receptor-like protein (LecRLP). Like other LecRLPs that have been implicated in resistance, this gene could be a good candidate forHbresistance. The reported strategy can be applied as a general strategic approach for identifying genes underlying traits of interest in crop wild relatives.