The growing human population and a changing environment have raised significant concern for global food security, with the current improvement rate of several important crops inadequate to meet future demand . This slow improvement rate is attributed partly to the long generation times of crop plants. Here, we present a method called 'speed breeding', which greatly shortens generation time and accelerates breeding and research programmes. Speed breeding can be used to achieve up to 6 generations per year for spring wheat (Triticum aestivum), durum wheat (T. durum), barley (Hordeum vulgare), chickpea (Cicer arietinum) and pea (Pisum sativum), and 4 generations for canola (Brassica napus), instead of 2-3 under normal glasshouse conditions. We demonstrate that speed breeding in fully enclosed, controlled-environment growth chambers can accelerate plant development for research purposes, including phenotyping of adult plant traits, mutant studies and transformation. The use of supplemental lighting in a glasshouse environment allows rapid generation cycling through single seed descent (SSD) and potential for adaptation to larger-scale crop improvement programs. Cost saving through light-emitting diode (LED) supplemental lighting is also outlined. We envisage great potential for integrating speed breeding with other modern crop breeding technologies, including high-throughput genotyping, genome editing and genomic selection, accelerating the rate of crop improvement.

The activity of surface receptors is location specific, dependent upon the dynamic membrane trafficking network and receptor-mediated endocytosis (RME). Therefore, the spatio-temporal dynamics of RME are critical to receptor function. The plasma membrane receptor flagellin sensing2 (FLS2) confers immunity against bacterial infection through perception of flagellin (flg22). Following elicitation, FLS2 is internalized into vesicles. To resolve FLS2 trafficking, we exploited quantitative confocal imaging for colocalization studies and chemical interference. FLS2 localizes to bona fide endosomes via two distinct endocytic trafficking routes depending on its activation status. FLS2 receptors constitutively recycle in a Brefeldin A (BFA)-sensitive manner, while flg22-activated receptors traffic via ARA7/Rab F2b- and ARA6/Rab F1-positive endosomes insensitive to BFA. FLS2 endocytosis required a functional Rab5 GTPase pathway as revealed by dominant-negative ARA7/Rab F2b. Flg22-induced FLS2 endosomal numbers were increased by Concanamycin A treatment but reduced by Wortmannin, indicating that activated FLS2 receptors are targeted to late endosomes. RME inhibitors Tyrphostin A23 and Endosidin 1 altered but did not block induced FLS2 endocytosis. Additional inhibitor studies imply the involvement of the actin-myosin system in FLS2 internalization and trafficking. Altogether, we report a dynamic pattern of subcellular trafficking for FLS2 and reveal a defined framework for ligand-dependent endocytosis of this receptor.

Crop production needs to increase to secure future food supplies, while reducing its impact on ecosystems. Detailed characterization of plant genome structure and genetic diversity is crucial for meeting these challenges. Advances in genome sequencing and assembly are being used to access to the large and complex genomes of crops and their wild relatives. Sequencing of wild crop relatives is identifying a wide spectrum of genetic variation, permitting the association of genetic diversity with diverse agronomic phenotypes. In combination with improved and automated phenotyping assays and functional genomic studies, genomics is providing new foundations for crop-breeding systems. In the twentieth century, famines caused by political crises, mismanagement of food production or genocide killed an estimated 70 million people and were second only to war as the greatest manmade cause of death 1 . The father of the Green Revolution, Norman Borlaug, summarized the importance of crops: "Without food, people perish, social and political organizations disintegrate, and civilizations collapse. " For thousands of years, people have dedicated considerable resources to securing food supplies; for example, grain supplies to ancient Rome were secured through an extensive network of long-distance transport, and the distribution of grain was coordinated and subsidized by the cura annonae ('care for the grain supply'), an important figure who contributed to the maintenance of political unity and power.During the past 10,000 years, a period known as the Holocene, Earth's environment has been unusually stable. This probably facilitated the domestication of crops from wild species, resulting in steadily improved yields and adaptation to new agricultural areas. The production of food is now carried out on a vast scale, with 38% of Earth's surface dedicated to agriculture 2 . This increased production is having a pervasive influence on ecosystems worldwide: nitrogen production for agriculture accounts for 1.2% of global energy consumption 3 ; photosynthesis can no longer maintain stable levels of atmospheric carbon dioxide; and food production consumes around 70% of freshwater supplies. The modelling of crop responses to increases in temperature predicts that there will be a considerable reduction in the yield of rice, an important crop around the world 4 . Climate change could also alter the dynamics of crop pathogenic agents by altering the range of vectors and by compromising the immune response of crops 5 .Crop production must therefore adapt to more variable environments and the substantial impact it has on the environment needs to be reduced. Productivity must also increase at a much greater rate than in the past to meet the needs of Earth's growing population 6 . Genetic improvements in crop performance continue to be crucial for increasing crop productivity, but current rates of improvement are unable to meet the demands of sustainability and food security 7 . Plant genomics has a central role in the improvement of crops, includi...

Potato late blight, caused by the destructive Irish famine pathogen Phytophthora infestans, is a major threat to global food security(1,2). All late blight resistance genes identified to date belong to the coiled-coil, nucleotide-binding, leucine-rich repeat class of intracellular immune receptors(3). However, virulent races of the pathogen quickly evolved to evade recognition by these cytoplasmic immune receptors(4). Here we demonstrate that the receptor-like protein ELR (elicitin response) from the wild potato Solanum microdontum mediates extracellular recognition of the elicitin domain, a molecular pattern that is conserved in Phytophthora species. ELR associates with the immune co-receptor BAK1/SERK3 and mediates broad-spectrum recognition of elicitin proteins from several Phytophthora species, including four diverse elicitins from P. infestans. Transfer of ELR into cultivated potato resulted in enhanced resistance to P. infestans. Pyramiding cell surface pattern recognition receptors with intracellular immune receptors could maximize the potential of generating a broader and potentially more durable resistance to this devastating plant pathogen.

Sensing of potential pathogenic bacteria is of critical importance for immunity. In plants, this involves plasma membrane-resident pattern recognition receptors, one of which is the FLAGELLIN SENSING 2 (FLS2) receptor kinase. Ligand-activated FLS2 receptors are internalized into endosomes. However, the extent to which these spatiotemporal dynamics are generally present among pattern recognition receptors (PRRs) and their regulation remain elusive. Using live-cell imaging, we show that at least three other receptor kinases associated with plant immunity, PEP RECEPTOR 1/2 (PEPR1/2) and EF-TU RECEPTOR (EFR), internalize in a ligand-specific manner. In all cases, endocytosis requires the coreceptor BRI1-ASSOCIATED KINASE 1 (BAK1), and thus depends on receptor activation status. We also show the internalization of liganded FLS2, suggesting the transport of signaling competent receptors. Trafficking of activated PRRs requires clathrin and converges onto the same endosomal vesicles that are also shared with the hormone receptor BRASSINOSTERIOD INSENSITIVE 1 (BRI1). Importantly, clathrin-dependent endocytosis participates in plant defense against bacterial infection involving FLS2-mediated stomatal closure and callose deposition, but is uncoupled from activation of the flagellin-induced oxidative burst and MAP kinase signaling. In conclusion, immunity mediated by pattern recognition receptors depends on clathrin, a critical component for the endocytosis of signaling competent receptors into a common endosomal pathway.pattern-triggered immunity | clathrin | FLS2 | PEPR1 | EFR

Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance.

IMPORTANCEShortly after the emergence of the 2009 pandemic H1N1 (pdm/09) influenza virus, it was transmitted from humans to pigs and this continues to occur around the world. Many reassortants between pdm/09-origin viruses and enzootic swine influenza viruses (SIVs) have been detected. However, the long-term impact of pdm/09-origin viruses on the SIV gene pool, which could lead to the generation of influenza viruses with the potential to infect humans, has not been systematically examined. From extensive surveillance of SIVs over a 38-month period in southern China, it was found that although neither complete pdm/09 viruses nor their surface genes could persist in pigs, their internal genes did persist. Over the survey period, these internal genes became predominant, potentially replacing those of the enzootic SIV lineages. The altered diversity of the SIV gene pool needs to be closely monitored for changes in the potential for SIV transmission to humans.

25Progress in remote sensing and robotic technologies decreases the hardware costs of 26 phenotyping. Here, we first review cost-effective imaging devices and environmental sensors, 27 and present a trade-off between investment and manpower costs. We then discuss the structure 28 of costs in various real-world scenarios. Hand-held low-cost sensors are suitable for quick and 29 infrequent plant diagnostic measurements. In experiments for genetic or agronomic analyses, (i) 30 major costs arise from plant handling and manpower; (ii) the total costs per pot/microplot are 31 similar in robotized platform or field experiments with drones, hand-held or robotized ground 32 vehicles; (iii) the cost of vehicles carrying sensors represents only 5-26% of the total costs. These 33 conclusions depend on the context, in particular for labor cost, the quantitative demand of 34 phenotyping and the number of days available for phenotypic measurements due to climatic 35 constraints. Data analysis represents 10-20% of total cost if pipelines have already been 36 developed. A trade-off exists between the initial high cost of pipeline development and labor cost 37 of manual operations. Overall, depending on the context and objectives, "cost-effective" 38 phenotyping may involve either low investment ("affordable phenotyping"), or initial high 39 investments in sensors, vehicles and pipelines that result in higher quality and lower operational 40 costs. 41 Highlights 42 -New technologies considerably reduce the costs of sensors and automated vehicles 43 -Low investment in sensors, vehicles or pipelines present trade-offs with labor costs 44 -Plant/plot handling and labor costs represent the major proportion of costs in phenotyping 45 experiments 46 -The costs of high-throughput experiments in the field and in automated platforms is similar 47 regardless of vehicles 48 -The development of software applications (e.g. imaging, phenotypic analyses, models, 49 information system) is a major part of costs 50 51 52 54 I Imaging techniques with a range of hardware costs 55 1.1 Handheld phenotyping technologies 56 1.2 Aerial imaging for large-scale phenotyping 57 1.3 Imaging with ground vehicles 58 1.4 Environmental measurements 59 II Costs associated with image capture represent a fraction of the overall cost of phenotyping 60 2.1 A method for calculating costs in field and greenhouse platforms 61 2.2 A high cost for plant management 62 2.3 Investing in appropriate environmental characterization results in comparatively low cost 63 for a high return 64 2.4 Imaging costs: a trade-off between investment and labor costs 65 2.4.1 The choice of vehicle mostly depends on the demand for microplots per year 66 2.4.2 The cost of imaging devices is similar to that of vehicles that carry sensors 67 2.5 Costs of typical experiments 68 2.5.1 Image analysis: a tradeoff between investment in automated workflows and day-to-day 69 labor costs 70 2.5.2 High costs for data analysis for the identification of traits 71 2.5.3 Costs associated with data storag...