BackgroundModern civilization depends on only a few plant species for its nourishment. These crops were derived via several thousands of years of human selection that transformed wild ancestors into high-yielding domesticated descendants. Among cultivated plants, common bean (Phaseolus vulgaris L.) is the most important grain legume. Yet, our understanding of the origins and concurrent shaping of the genome of this crop plant is limited.ResultsWe sequenced the genomes of 29 accessions representing 12 Phaseolus species. Single nucleotide polymorphism-based phylogenomic analyses, using both the nuclear and chloroplast genomes, allowed us to detect a speciation event, a finding further supported by metabolite profiling. In addition, we identified ~1200 protein coding genes (PCGs) and ~100 long non-coding RNAs with domestication-associated haplotypes. Finally, we describe asymmetric introgression events occurring among common bean subpopulations in Mesoamerica and across hemispheres.ConclusionsWe uncover an unpredicted speciation event in the tropical Andes that gave rise to a sibling species, formerly considered the “wild ancestor” of P. vulgaris, which diverged before the split of the Mesoamerican and Andean P. vulgaris gene pools. Further, we identify haplotypes strongly associated with genes underlying the emergence of domestication traits. Our findings also reveal the capacity of a predominantly autogamous plant to outcross and fix loci from different populations, even from distant species, which led to the acquisition by domesticated beans of adaptive traits from wild relatives. The occurrence of such adaptive introgressions should be exploited to accelerate breeding programs in the near future.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-017-1190-6) contains supplementary material, which is available to authorized users.

Climatic change is an increasing challenge for agriculture that is driving the development of suitable crops in order to ensure supply for both human nutrition and animal feed. In this context, it is increasingly important to understand the biochemical responses of cells to environmental cues at the whole system level, an aim that is being brought closer by advances in high throughput, cost-efficient plant metabolomics. To support molecular breeding activities, we have assessed the economic, technical and statistical feasibility of using direct mass spectrometry methods to evaluate the physiological state of maize (Zea mays L.) plants grown under different stress conditions.

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High-throughput metabolic phenotyping is a challenge, but it provides an alternative and comprehensive access to the rapid and accurate characterization of plants. In addition to the technical issues of obtaining quantitative data of plenty of metabolic traits from numerous samples, a suitable data processing and statistical evaluation strategy must be developed. We present a simple, robust and highly scalable strategy for the comparison of multiple chemical profiles from coffee and tea leaf extracts, based on direct-injection electrospray mass spectrometry (DIESI-MS) and hierarchical cluster analysis (HCA). More than 3500 individual Coffea canephora and Coffea arabica trees from experimental fields in Mexico were sampled and processed using this method. Our strategy permits the classification of trees according to their metabolic fingerprints and the screening for families with desired characteristics, such as extraordinarily high or low caffeine content in their leaves.

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Programmed cell death 1 (PD-1) and its ligands PD-L1 and PD-L2 are receptors that act in co-stimulatory and coinhibitory immune responses. Signaling the PD-1/PD-L1 or PD-L2 pathway is essential to regulate the inflammatory responses to infections, autoimmunity, and allergies, and it has been extensively studied in cancer. Allergic diseases include asthma, rhinoconjunctivitis, atopic dermatitis, drug allergy, and anaphylaxis. These overactive immune responses involve IgE-dependent activation and increased CD4+ T helper type 2 (Th2) lymphocytes. Recent studies have shown that PD-L1 and PD-L2 act to regulate T-cell activation and function. However, the main role of PD-1 and its ligands is to balance the immune response; however, the inflammatory process of allergic diseases is poorly understood. These immune checkpoint molecules can function as a brake or a kick-start to regulate the adaptive immune response. These findings suggest that PD-1 and its ligands may be a key factor in studying the exaggerated response in hypersensitivity reactions in allergies. This review summarizes the current understanding of the role of PD-1 and PD-L1 and PD-L2 pathway regulation in allergic diseases and how this immunomodulatory pathway is currently being targeted to develop novel therapeutic immunotherapy.

Biofertilizer production and application for sustainable agriculture is already a reality. The methods for biofertilizers delivery in crop fields are diverse. Although foliar spray is gaining wide acceptance, little is known about the influence that the biochemical features of leaves have on the microbial colonization. Arthrobacter agilis UMCV2 is a rhizospheric and endophytic bacteria that promotes plant growth and health. In this study, we determined the capacity of the UMCV2 strain to colonize different leaves from Medicago truncatula in a foliar inoculation system. By using two powerful analytical methods based on mass spectrometry, we determined the chemical profile of the leaves in 15-d old plants. The metabolic signatures between the unifoliate leaf (m1) and the metameric units developing above (m2 and m3) were different, and interestingly, the highest colony forming units (CFU) was found in m1. The occurrence of the endophyte strongly affects the sugar composition in m1 and m2 leaves. Our results suggest that A. agilis UMCV2 colonize the leaves under a foliar inoculation system independently of the phenological age of the leaf and it is capable of modulating the carbohydrate metabolism without affecting the rest of the metabolome. Plants live in a close relationship with different microbial communities that reside inside or outside the plant tissues. The inside colonizers are referred as endophytes (from the Greek endon-within and phyton-plant), and when they are inside the plant, they completely depend on the plant and its internal conditions for growth 1-5. A study of Arabidopsis thaliana grown under natural conditions showed that the bacterial community associated with the outside of the roots were more diverse than in the endophytic community, while the opposite pattern was observed in the leaves 6. In addition, the authors found that leaves and roots shared many species of bacterial endophytes, suggesting that some root endosphere colonizers migrate and are capable of colonizing above-ground tissues; thus the microbial traits for competition and colonization influence the richness and composition of the plant endophytes 7,8. According to the literature, the endophytes are non-pathogenic, but some of them could act as latent pathogens that can cause disease, depending on the stressful environmental circumstances 4,9. Studies of the functional capacity of beneficial endophytes have revealed their potential as promoters of plant growth and health, moreover, they are free from the environmental pressure of changing soil and climate conditions experienced by their rhizospheric counterparts, so they are an excellent candidate for biofertilizers 10,11. The delivery methods of endophytes in agriculture include seed inoculation, soil drenching, stem injection, and foliar fertilization. Currently, there is a renewed interest in a foliar-treated plants and different studies on the effect of bacterial and fungal endophytes on the growth, crop production, nutrient uptake, and defense have appeared in the literatu...