Human induced climate and land-use change are severely impacting global biodiversity, but how community composition and richness of multiple taxonomic groups change in response to local drivers and whether these responses are synchronous remains unclear. We used long-term community-level data from an experimentally manipulated grassland to assess the relative influence of climate and land use as drivers of community structure of four taxonomic groups: birds, mammals, grasshoppers, and plants. We also quantified the synchrony of responses among taxonomic groups across land-use gradients and compared climatic drivers of community structure across groups. All four taxonomic groups responded strongly to land use (fire frequency and grazing), while responses to climate variability were more pronounced in grasshoppers and small mammals. Animal groups exhibited asynchronous responses across all land-use treatments, but plant and animal groups, especially birds, exhibited synchronous responses in composition. Asynchrony was attributed to taxonomic groups responding to different components of climate variability, including both current climate conditions and lagged effects from the previous year. Data-driven land management strategies are crucial for sustaining native biodiversity in grassland systems, but asynchronous responses of taxonomic groups to climate variability across land-use gradients highlight a need to incorporate response heterogeneity into management planning.

16Wild relatives of hexaploid wheat (Triticum aestivum) are the reservoirs of novel allelic 17 diversity with great potential to improve many agronomic traits in wheat. Here, we 18 investigated the genome-wide patterns and efficiency of Aegilops tauschii allele introgression 19 into the winter wheat cultivars. The introgression population of 351 BC 1 F 3 : 5 lines was 20 selected based on phenology and development characteristics from crosses between six 21 hexaploid wheat lines and 21 wheat-Ae. tauschii octoploids. Complexity reduced genomic 22 library sequencing was used to develop SNP markers and infer the regions of identity-by-23 descent and the boundaries of the introgressed segments. Using a diverse panel of 116 Ae. 24 tauschii accessions, it was possible to infer that introgression lines had single or multiple IBD 25 segments from accessions of diverse geographic origin. Introgression frequency was high at 26 the ends of chromosomes and low in the large pericentromeric 2/3 of the chromosome arms 27 characterized by low crossover rate. While the effect of selection for free-threshing genotypes 28 was evident around the domestication gene Tg, reduction in the frequency of introgression 29 was limited to relatively small regions flanking the gene. These results suggest that the 30 effects of phenotypic selection on the introgressed wild relative's alleles at the early 31 generations of population development are strongly influenced by the distribution of 32 crossover frequency across genome, consistent with the Hill-Robertson effect. Our study 33 offers insights into the introgression population development to ensure retention of genetic 34 2 diversity across entire genome and presents a resource that will be valuable for deploying 35 wild relative diversity in breeding programs to create climate resilient and disease resistant 36 varieties with improved yield and quality traits. 37 38Introduction 39Wheat production is constrained by several biotic and abiotic factors, yet the demand 40 for wheat is expected to double by 2050. A yield increase of ~2.4 % per year has been 41 projected as required to close the gap between the current production level and an increasing 42 demand (Ray et al. 2013). While this goal can be achieved by improving agronomic 43 practices, expanding the production area and/or deployment of high-yielding wheat varieties, 44 the first two alternatives are unsustainable because land is a limited resource and most 45 effective agronomic practices are costly. Accelerated wheat improvement through extensive 46 deployment of available genomics tools and genetic resources, including close and distant 47 wild relatives of wheat, is viewed as the most effective and sustainable alternative to 48 increasing yield. 49Allohexaploid wheat, Triticum aestivum (2n = 6x = 42, AABBDD) resulted from 50 hybridization of Triticum turgidum (2n = 4x = 28, AABB) and Aegilops tauschii ssp. 51 strangulata (2n = 2x = 14, DD) (Kihara 1944; Luo et al. 2007;Wang et al. 2013). 52 Domestication of wheat followed by con...

Introgression from wild relatives is a valuable source of novel allelic diversity for breeding. We investigated the genomic patterns of introgression from Aegilops tauschii, the diploid ancestor of the wheat D genome, into winter wheat (Triticum aestivum) cultivars. The population of 351 BC1F3:5 lines was selected based on phenology from crosses between six hexaploid wheat lines and 21 wheat-Ae. tauschii octoploids. SNP markers developed for this population and a diverse panel of 116 Ae. tauschii accessions by complexity-reduced genome sequencing were used to detect introgression based on the identity-by-descent analysis. Overall, introgression frequency positively correlated with recombination rate, with a high incidence of introgression at the ends of chromosomes and low in the pericentromeric regions, and was negatively related to sequence divergence between the parental genomes. Reduced introgression in the pericentromeric low-recombining regions spans nearly 2/3 of each chromosome arm, suggestive of the polygenic nature of introgression barriers that could be associated with multilocus negative epistasis between the alleles of wild and cultivated wheat. On the contrary, negative selection against the wild allele of Tg, controlling free-threshing trait and located in the high-recombining chromosomal region, led to reduced introgression only within ~10 Mbp region around Tg. These results are consistent with the effect of selection on linked variation described by the Hill-Robertson effect, and offer insights into the introgression population development for crop improvement to maximize retention of introgressed diversity across entire genome.

Stripe rust is a devastating disease in wheat that causes substantial yield loss around the world. The most effective strategy for mitigating yield loss is to develop resistant cultivars. The wild relatives of wheat are good sources of resistance to fungal pathogens. Here, we used a genome-wide association study (GWAS) to identify loci associated with stripe rust (causal agent: Puccinia striiformis f. sp. tritici) resistance in wild emmer (Triticum dicoccoides) at the seedling stage, in the greenhouse, and at the adult plant stage, in the field. We found that the two major loci contributing to resistance in our wild emmer panel were the previously cloned seedling-stage resistance gene, Yr15, and the adult-plant-stage resistance gene, Yr36. Nevertheless, we detected 12 additional minor QTLs that additionally contribute to adult plant resistance and mapped a locus on chromosome 3AS that tentatively harbors a novel seedling resistance gene. The genotype and phenotype data generated for the wild emmer panel, together with the detected SNPs associated with resistance to stripe rust, provide a valuable resource for disease-resistance breeding in durum and bread wheat.

The introgression from wild relatives have a great potential to broaden the availability of beneficial allelic diversity for crop improvement in breeding programs. Here, we assessed the impact of the introgression from 21 diverse accessions of Aegilops tauschii, the diploid ancestor of the wheat D genome, into 6 hard red winter wheat cultivars on yield and yield component traits. We used 5.2 million imputed D genome SNPs identified by the whole-genome sequencing of parental lines and the sequence-based genotyping of introgression population, including 351 BC1F3:5 lines. Phenotyping data collected from the irrigated and non-irrigated field trials revealed that up to 23% of the introgression lines (ILs) produce more grain than the parents and check cultivars. Based on 16 yield stability statistics, the yield of 12 ILs (3.4%) was stable across treatments, years, and locations; 5 of these lines were also high yielding lines, producing 9.8% more grain than the average yield of check cultivars. The most significant SNP- and haplotype-trait associations were identified on chromosome arms 2DS and 6DL for the spikelet number per spike (SNS), on chromosome arms 2DS, 3DS, 5DS, and 7DS for grain length (GL) and on chromosome arms 1DL, 2DS, 6DL, and 7DS for grain width (GW). The introgression of haplotypes from A. tauschii parents was associated with an increase in SNS, which was positively correlated with a heading date (HD), whereas the haplotypes from hexaploid wheat parents were associated with an increase in GW. We show that the haplotypes on 2DS associated with an increase in the spikelet number and HD are linked with multiple introgressed alleles of Ppd-D1 identified by the whole-genome sequencing of A. tauschii parents. Meanwhile, some introgressed haplotypes exhibited significant pleiotropic effects with the direction of effects on the yield component traits being largely consistent with the previously reported trade-offs, there were haplotype combinations associated with the positive trends in yield. The characterized repertoire of the introgressed haplotypes derived from A. tauschii accessions with the combined positive effects on yield and yield component traits in elite germplasm provides a valuable source of alleles for improving the productivity of winter wheat by optimizing the contribution of component traits to yield.

Introgression from wild relatives have a great potential to broaden beneficial allelic diversity available for crop improvement in breeding programs. Here, we assessed the impact of introgression from 21 diverse accessions of Aegilops tauschii, the diploid ancestor of the wheat D genome, into six hard red winter wheat cultivars on yield and yield component traits. We used 5.2 million imputed D genome SNPs identified by whole-genome sequencing of parental lines and the sequence-based genotyping of introgression population including 351 BC1F3:5 lines. Phenotyping data collected from the irrigated and non-irrigated field trials revealed that up to 23% of the introgression lines produce more grain than the parents and check cultivars. Based on sixteen yield stability statistics, the yield of twelve introgression lines (3.4%) was stable across treatments, years and locations; five of these lines were also high yielding, producing 9.8% more grain than the average yield of check cultivars. The most significant SNP-trait and haplotype-trait associations were identified on chromosome arms 2DS and 6DL for spikelet number per spike (SNS), on chromosome arms 2DS, 3DS, 5DS and 7DS for grain length and on chromosome arms 1DL, 2DS, 6DL and 7DS for grain width. Introgression of haplotypes from Ae. tauschii parents was associated with increase in SNS, which positively correlated with heading date, whereas haplotypes from hexaploid wheat parents were associated with increased grain width. While some introgressed haplotypes exhibited significant pleiotropic effects with the direction of effects on the yield component traits being largely consistent with the previously reported trade-offs, there were haplotype combinations associated with the positive trends in yield. The characterized repertoire of the introgressed haplotypes derived from Ae. tauschii accessions with the combined positive effects on yield and yield components traits in elite germplasm provides a valuable source of alleles for improving the productivity of winter wheat by optimizing the contribution of component traits to yield.