Correction: Autoacetylation of the Ralstonia solanacearum Effector PopP2 Targets a Lysine Residue Essential for RRS1-R-Mediated Immunity in Arabidopsis.

[This corrects the article DOI: 10.1371/journal.ppat.1001202.].

Long-term outcome of pediatric renal transplantation with donors younger than 6 years.

BACKGROUND: Renal transplantation is currently the best treatment option for patients with end-stage renal disease. However, the use of kidneys from donors under 6 years of age as a possibility to increase the organ pool in pediatric recipients remains a controversial matter. We aimed to investigate whether donor age is associated to the long-term functionality of the renal graft. Likewise, we analyzed the adaptation of the graft to the ascending functional requirements in the pediatric patient. METHODS: Retrospective study of the results obtained in pediatric recipients transplanted with grafts from donors between 3 and 6 years of age, comparing them with those of grafts from donors older than 6 years. Among the variables compared are cumulative graft survival, renal size, need for antiproteinuric therapy, GFR, incidence of rejection, pyelonephritis, renal failure and surgical or tumor complications. RESULTS: A total of 43 transplants were performed with donors aged 3-6 years, and 42 transplants with donors older than 6 years. Cumulative graft survival at 5 years was 81% for the younger donor group compared to 98% for the older donor group (p < .05). At 8 years, cumulative graft survival for donors <6 years was 74%. As for the mean estimated graft survival, it was 11.52 years for the younger donor group and 14.51 years for older donors. During follow-up, the younger donor group presented greater renal enlargement and need for antiproteinuric therapy. The older donors group had a higher GFR during the first year of follow-up, which then equalized in both groups. There were no statistically significant differences in the incidence of acute or chronic rejection, acute pyelonephritis, acute renal failure or surgical or tumor complications. CONCLUSIONS: Renal transplants of grafts equal to or less than 6 years old have good short-term and acceptable long-term results in pediatric patients.

Adaptation and validation of the Physical Restraint-Theory of Planned Behaviour Questionnaire to the paediatric context.

OBJECTIVE: To create and test psychometrically a paediatric version of the Physical Restraint-Theory of Planned Behaviour Questionnaire to assess paediatric critical care nurses' intention to use physical restraint. DESIGN: A psychometric study. SETTING: Five medical-surgical Paeditric Intensive care Units from five hospitals in Spain. METHODS: The study took place in three phases. In phase 1, the questionnaire was adapted. In phase 2, the content validity of each item was determined, and a pilot test was conducted. In phase 3, we administered the questionnaire and determined its psychometric properties. RESULTS: The assessment of the intention to use physical restraint was extended to all critical paediatric patients, two items were eliminated from the initial questionnaire, four new items were included, and the clinical scenarios of the intention subscale were expanded from three to six. Overall content validity index for the full instrument of 0.96 out of 1. The Paediatric Physical Restraint-Theory of Planned Behaviour Questionnaire is made up of four subscales (attitude, subjective norms (SN), perceived behavioural control (PBC), and intention) subdivided into 7 factors and 51 items. The internal consistency for the attitude subscale obtained a Cronbach's Alpha of 0.80 to 0.73, for the SN it was 0.72 to 0.89, for the PBC it was from 0.80 to 0.73 and for the intention subscale it was 0.75. CONCLUSIONS: The Paediatric Physical Restraint-Theory of Planned Behaviour Questionnaire is an instrument composed of seven factors and 51 items that validly and reliably assesses the intention of paediatric nurses to apply PR in PICUs. RELEVANCE FOR CLINICAL PRACTICE: Having this instrument will help health centres move towards restraint-free care by allowing managers to assess professionals' attitudes, beliefs, and intentions around the use of PR in PICUs.

Retracted: "CITRX thioredoxin interacts with the tomato Cf-9 resistance protein and negatively regulates defence".

The authors regret to announce they would like to withdraw this paper, for two main reasons: Since the paper was published, it has become clear that the thioredoxin that interacts in yeast 2-hybrid with the Cf-9 C-terminus is in fact localized in the chloroplast, rendering a role in Cf-9 signalling unlikely. Close scrutiny of the figures suggests several duplications. - In Fig 3A, the Anti-MBP band in lane 4 closely resembles the antiMBP band in Fig 3B lane 1, though slightly rotated. - In Fig 6A, the leaf disc in the panel labelled TRV:00, -Avr9, 30 min looks identical to the leaf disc in Fig S5, panel labelled Cf2 TRV:CITRX, -Avr2, 1 h. - In Fig 6C, multiple bands appear duplicated. For example, GlucA, TRV:00, -Avr9, 0 h duplicated with 6 h; and GlucB, TRV:00, +Avr9, 0 h duplicated with Hin1, TRV:00, +Avr9, 0 h. Source data for these figures are not available. All the authors agree that this paper should be withdrawn from the scientific literature.

Surrogate biomarkers of outcome for wake-up ischemic stroke.

BACKGROUND: Wake-up ischemic stroke (IS) has been usually excluded from acute stroke therapy options for being outside of the safe treatment window. We identified risk factors, and clinical or molecular biomarkers that could be therapeutic targets for wake-up stroke prevention, thus hopefully leading to a decrease in its mortality and disability in medium to long-term outcome. METHODS: 4251 ischemic stroke (IS) patients from a prospectively registered database were recruited; 3838 (90.3%) had known onset-symptom time, and 413 (9.7%) were wake-up strokes. The main endpoint was to analyze the association between different serum biomarkers with wake-up IS episodes and their progression. Leukocytes count, serum levels of C-reactive protein, fibrinogen, interleukin 6 (IL-6), and vitamin D were analyzed as inflammation biomarkers; N-terminal pro-B-type Natriuretic-Peptide and microalbuminuria, used as atrial/endothelial dysfunction biomarkers; finally, glutamate levels as excitotoxicity biomarker. In addition, demographic, clinical and neuroimaging variables associated with the time-evolution of wake-up IS patients and functional outcome at 3 months were evaluated. Good and poor functional outcome were defined as mRS ≤2 and mRS > 2 at 3 months, respectively. RESULTS: Wake-up IS showed a poorer outcome at 3-months than in patients with known on-set-symptom time (59.1% vs. 48.1%; p < 0.0001). Patients with wake-up IS had higher levels of inflammation biomarkers; IL-6 levels at admission (51.5 ± 15.1 vs. 27.8 ± 18.6 pg/ml; p < 0.0001), and low vitamin D levels at 24 h (5.6 ± 5.8 vs. 19.2 ± 9.4 ng/ml; p < 0.0001) are worthy of attention. In a logistic regression model adjusted for vitamin D, OR was 15.1; CI 95%: 8.6-26.3, p < 0.0001. However, we found no difference in vitamin D levels between patients with or without clinical-DWI mismatch (no: 18.95 ± 9.66; yes: 17.84 ± 11.77 ng/mL, p = 0.394). No difference in DWI volume at admission was found (49.3 ± 96.9 ml in wake-up IS patients vs. 51.7 ± 98.2 ml in awake IS patients; p = 0.895). CONCLUSIONS: Inflammatory biomarkers are the main factors that are strongly associated with wake-up IS episodes. Wake-up IS is associated with lower vitamin D levels. These data indicate that vitamin D deficiency could become a therapeutic target to reduce wake-up IS events.

Artificial urinary sphincter in congenital neuropathic bladder: Very long-term outcomes.

OBJECTIVE: Artificial urinary sphincter has been used to treat urinary incontinence in children with neuropathic bladder, although there are few studies reporting very long-term results. We assess our experience over the last 27 years in the management of artificial urinary sphincter. METHODS: A retrospective study was performed in patients with neuropathic bladder in whom an artificial urinary sphincter was placed in our institution between 1994 and 2020. Demographic variables, pre- and post-artificial urinary sphincter implantation urodynamic studies, long-term outcomes, and postoperative complications were collected. RESULTS: An artificial urinary sphincter was implanted in 71 patients (median age 14.5; interquartile range 12.8-15.9), with a median follow-up time of 17.2 years (interquartile range 9.8-23.9 years). Thirty-nine patients underwent enterocystoplasty combined with artificial urinary sphincter placement and 32 underwent artificial urinary sphincter implantation alone, of whom 12 patients (16.9%) eventually required an enterocystoplasty because of unexpected bladder behavior changes, usually within 3 years of artificial urinary sphincter implantation. Adequate urinary continence was reported in 90.1% of patients, nine void their bladders spontaneously, and 62 need clean intermittent catheterization. Eighteen mechanical malfunctions occurred in 15 patients (21.1%), with an average artificial urinary sphincter working life of 15.1 ± 1.3 years. In five patients artificial urinary sphincter was removed due to infection or erosion. In 12 patients (30.8%), a continent catheterizable stoma was made (before or during the follow-up) because of problems with clean intermittent catheterization through the urethra. CONCLUSION: The very long-term results of this study demonstrate that artificial urinary sphincter is an effective treatment for urinary incontinence in neuropathic bladder patients. Long-term follow-up is important to identify potential unexpected changes in bladder behavior in these patients.

Early Neurological Change After Ischemic Stroke Is Associated With 90-Day Outcome.

BACKGROUND AND PURPOSE: Large-scale observational studies of acute ischemic stroke (AIS) promise to reveal mechanisms underlying cerebral ischemia. However, meaningful quantitative phenotypes attainable in large patient populations are needed. We characterize a dynamic metric of AIS instability, defined by change in National Institutes of Health Stroke Scale score (NIHSS) from baseline to 24 hours baseline to 24 hours (NIHSSbaseline - NIHSS24hours = ΔNIHSS6-24h), to examine its relevance to AIS mechanisms and long-term outcomes. METHODS: Patients with NIHSS prospectively recorded within 6 hours after onset and then 24 hours later were enrolled in the GENISIS study (Genetics of Early Neurological Instability After Ischemic Stroke). Stepwise linear regression determined variables that independently influenced ΔNIHSS6-24h. In a subcohort of tPA (alteplase)-treated patients with large vessel occlusion, the influence of early sustained recanalization and hemorrhagic transformation on ΔNIHSS6-24h was examined. Finally, the association of ΔNIHSS6-24h with 90-day favorable outcomes (modified Rankin Scale score 0-2) was assessed. Independent analysis was performed using data from the 2 NINDS-tPA stroke trials (National Institute of Neurological Disorders and Stroke rt-PA). RESULTS: For 2555 patients with AIS, median baseline NIHSS was 9 (interquartile range, 4-16), and median ΔNIHSS6-24h was 2 (interquartile range, 0-5). In a multivariable model, baseline NIHSS, tPA-treatment, age, glucose, site, and systolic blood pressure independently predicted ΔNIHSS6-24h (R2=0.15). In the large vessel occlusion subcohort, early sustained recanalization and hemorrhagic transformation increased the explained variance (R2=0.27), but much of the variance remained unexplained. ΔNIHSS6-24h had a significant and independent association with 90-day favorable outcome. For the subjects in the 2 NINDS-tPA trials, ΔNIHSS3-24h was similarly associated with 90-day outcomes. CONCLUSIONS: The dynamic phenotype, ΔNIHSS6-24h, captures both explained and unexplained mechanisms involved in AIS and is significantly and independently associated with long-term outcomes. Thus, ΔNIHSS6-24h promises to be an easily obtainable and meaningful quantitative phenotype for large-scale genomic studies of AIS.

Time Trends in Intracerebral Hemorrhage Associated with Oral Anticoagulation and Its Risks Factors in Spain from 2008 to 2015.

BACKGROUND: Intracerebral hemorrhage (ICH) is 7- to 10-fold higher in anticoagulated patients. Given the more extended use of oral anticoagulants, an increase in the prevalence of ICH associated with oral anticoagulation (ICH-OAC) could be expected. However, there is no previous study that assesses the time trends of ICH-OAC in Spain. METHODS: We conducted a combined data analysis after creating a joint database of the 3 most important epidemiological studies on ICH-OAC of our country: the EPICES study (2008-2009), the TAC Registry (TR) study (2012-2013) and the TAC Registry 2 (TR2) study (2015). We finally included 65, 235, and 366 patients from the EPICES, TR, and TR2 studies, respectively. RESULTS: We have observed a 3.73-fold increase in the crude annual incidence of ICH-OAC throughout the period of study, with proportion of ICH-OAC out of total ICH increasing from 8.4% in 2008 to 18.2% in 2015. Age, dyslipidemia, and prior antiplatelet treatment increased during the study, but we found no statistically significant differences in other risk factors for ICH-OAC. CONCLUSIONS: The incidence of ICH-OAC is increasing in our country. It might at least be partly explained by aging of the population, with mean age at presentation being higher in the last years.

Regulatory T cells participate in the recovery of ischemic stroke patients.

BACKGROUND: Recent preclinical studies have shown that regulatory T cells (Treg) play a key role in the immune response after ischemic stroke (IS). However, the role of Treg in human acute IS has been poorly investigated. Our aim was to study the relationship between circulating Treg and outcome in human IS patients. METHODS: A total of 204 IS patients and 22 control subjects were recruited. The main study variable was good functional outcome at 3 months (modified Rankin scale ≤2) considering infarct volume, Early Neurological Deterioration (END) and risk of infections as secondary variables. The percentage of circulating Treg was measured at admission, 48, 72 h and at day 7 after stroke onset. RESULTS: Circulating Treg levels were higher in IS patients compared to control subjects. Treg at 48 h were independently associated with good functional outcome (OR, 3.5; CI: 1.9-7.8) after adjusting by confounding factors. Patients with lower Treg at 48 h showed higher frequency of END and risk of infections. In addition, a negative correlation was found between circulating Treg at 48 h (r = - 0.414) and 72 h (r = - 0.418) and infarct volume. CONCLUSIONS: These findings suggest that Treg may participate in the recovery of IS patients. Therefore, Treg may be considered a potential therapeutic target in acute ischemic stroke.

A two genes - for - one gene interaction between Leptosphaeria maculans and Brassica napus.

Interactions between Leptosphaeria maculans, causal agent of stem canker of oilseed rape, and its Brassica hosts are models of choice to explore the multiplicity of 'gene-for-gene' complementarities and how they diversified to increased complexity in the course of plant-pathogen co-evolution. Here, we support this postulate by investigating the AvrLm10 avirulence that induces a resistance response when recognized by the Brassica nigra resistance gene Rlm10. Using genome-assisted map-based cloning, we identified and cloned two AvrLm10 candidates as two genes in opposite transcriptional orientation located in a subtelomeric repeat-rich region of the genome. The AvrLm10 genes encode small secreted proteins and show expression profiles in planta similar to those of all L. maculans avirulence genes identified so far. Complementation and silencing assays indicated that both genes are necessary to trigger Rlm10 resistance. Three assays for protein-protein interactions showed that the two AvrLm10 proteins interact physically in vitro and in planta. Some avirulence genes are recognized by two distinct resistance genes and some avirulence genes hide the recognition specificities of another. Our L. maculans model illustrates an additional case where two genes located in opposite transcriptional orientation are necessary to induce resistance. Interestingly, orthologues exist for both L. maculans genes in other phytopathogenic species, with a similar genome organization, which may point to an important conserved effector function linked to heterodimerization of the two proteins.

Life and death of proteins after protease cleavage: protein degradation by the N-end rule pathway.

Contents Summary 929 I. INTRODUCTION: conservation and diversity of N-end rule pathways 929 II. Defensive functions of the N-end rule pathway in plants 930 III. Proteases and degradation by the N-end rule pathway 930 IV. New proteomics approaches for the identification of N-end rule substrates 932 V. Concluding remarks 932 Acknowledgements 934 References 934 SUMMARY: The N-end rule relates the stability of a protein to the identity of its N-terminal residue and some of its modifications. Since its discovery in the 1980s, the repertoire of N-terminal degradation signals has expanded, leading to a diversity of N-end rule pathways. Although some of these newly discovered N-end rule pathways remain largely unexplored in plants, recent discoveries have highlighted roles of N-end rule-mediated protein degradation in plant defense against pathogens and in cell proliferation during organ growth. Despite this progress, a bottleneck remains the proteome-wide identification of N-end rule substrates due to the prerequisite for endoproteolytic cleavage and technical limitations. Here, we discuss the recent diversification of N-end rule pathways and their newly discovered functions in plant defenses, stressing the role of proteases. We expect that novel proteomics techniques (N-terminomics) will be essential for substrate identification. We review these methods, their limitations and future developments.

AtSERPIN1 is an inhibitor of the metacaspase AtMC1-mediated cell death and autocatalytic processing in planta.

The hypersensitive response (HR) is a localized programmed cell death phenomenon that occurs in response to pathogen recognition at the site of attempted invasion. Despite more than a century of research on HR, little is known about how it is so tightly regulated and how it can be contained spatially to a few cells. AtMC1 is an Arabidopsis thaliana plant metacaspase that positively regulates the HR. Here, we used an unbiased approach to identify new AtMC1 regulators. Immunoaffinity purification of AtMC1-containing complexes led us to the identification of the protease inhibitor AtSerpin1. Our data clearly showed that coimmunoprecipitation between AtMC1 and AtSerpin1 and formation of a complex between them was lost upon mutation of the AtMC1 catalytic site, and that the AtMC1 prodomain was not required for the interaction. AtSerpin1 blocked AtMC1 self-processing and inhibited AtMC1-mediated cell death. Our results constitute an in vivo example of a Serpin acting as a suicide inhibitor in plants, reminiscent of the activity of animal or viral serpins on immune/cell death regulators, including caspase-1. These results indicate a conserved function of a protease inhibitor on cell death regulators from different kingdoms with unrelated modes of action (i.e. caspases vs metacaspases).

From structure to function - a family portrait of plant subtilases.

Contents Summary 901 I. Introduction 901 II. Biochemistry and structure of plant SBTs 902 III. Phylogeny of plant SBTs and family organization 903 IV. Physiological roles of plant SBTs 905 V. Conclusions and outlook 911 Acknowledgements 912 References 912 SUMMARY: Subtilases (SBTs) are serine peptidases that are found in all three domains of life. As compared with homologs in other Eucarya, plant SBTs are more closely related to archaeal and bacterial SBTs, with which they share many biochemical and structural features. However, in the course of evolution, functional diversification led to the acquisition of novel, plant-specific functions, resulting in the present-day complexity of the plant SBT family. SBTs are much more numerous in plants than in any other organism, and include enzymes involved in general proteolysis as well as highly specific processing proteases. Most SBTs are targeted to the cell wall, where they contribute to the control of growth and development by regulating the properties of the cell wall and the activity of extracellular signaling molecules. Plant SBTs affect all stages of the life cycle as they contribute to embryogenesis, seed development and germination, cuticle formation and epidermal patterning, vascular development, programmed cell death, organ abscission, senescence, and plant responses to their biotic and abiotic environments. In this article we provide a comprehensive picture of SBT structure and function in plants.

Trends in stroke outcomes in the last ten years in a European tertiary hospital.

BACKGROUND: Studying the impact of demographic changes and progress in the management of stroke patients is necessary in order to organize care structures for the coming years. Consequently, we analyzed the prognostic trends of patients admitted to the Stroke Unit of a tertiary hospital in the last ten years. METHODS: The University Clinical Hospital of Santiago de Compostela is the referral hospital for stroke in a catchment area that accounts for 16.5% of the population of Galicia. Data from patients admitted to the Stroke Unit were registered prospectively. A multinomial logistic regression was performed to determine the influence of new trends in demographic factors and in the management of patients with acute stroke. For the expected trend of progression, a 2008-2011 and 2012-2017 time series model was made by selecting the most appropriate model. RESULTS: In the last 10 years, the age of stroke onset has only increased in women (from 74.4 ± 2.2 years in 2008 to 78.8 ± 2.1 years in 2017; p = 0.037), and the same happens with the severity of neurological symptoms (ischemic stroke (IS), p < 0.0001; from 14 [10, 19] in 2008 to 19 [15, 26] in 2017), with a higher percentage of cardioembolic strokes (40.7% vs. 32.2% of cardioembolic strokes in women vs. men, p < 0.0001). In a multiple linear regression model, hospital improvement was mainly associated with the use of reperfusion treatment (B 53.11, CI 95% 49.87, 56.36, p < 0.0001). A differentiated multinomial logistic regression analysis conducted for the whole sample with ischemic strokes in the two time periods (2008-2011 and 2012-2017) showed no differences in the influence of factors associated with higher morbidity and mortality. The modeling of time series showed a distinct falling trend in mortality, with a slight increase in good outcome as well as morbidity in both ischemic and hemorrhagic stroke. CONCLUSIONS: Our results showed that mortality decreased in the entire sample; however, although outcome at discharge improved in ischemic stroke, severe disability also increased in these patients. Importantly, this tendency towards increased morbidity seems to be confirmed for the coming years.

The Eucalyptus linker histone variant EgH1.3 cooperates with the transcription factor EgMYB1 to control lignin biosynthesis during wood formation.

Wood, also called secondary xylem, is a specialized vascular tissue constituted by different cell types that undergo a differentiation process involving deposition of thick, lignified secondary cell walls. The mechanisms needed to control the extent of lignin deposition depending on the cell type and the differentiation stage are far from being fully understood. We found that the Eucalyptus transcription factor EgMYB1, which is known to repress lignin biosynthesis, interacts specifically with a linker histone variant, EgH1.3. This interaction enhances the repression of EgMYB1's target genes, strongly limiting the amount of lignin deposited in xylem cell walls. The expression profiles of EgMYB1 and EgH1.3 overlap in xylem cells at early stages of their differentiation as well as in mature parenchymatous xylem cells, which have no or only thin lignified secondary cell walls. This suggests that a complex between EgMYB1 and EgH1.3 integrates developmental signals to prevent premature or inappropriate lignification of secondary cell walls, providing a mechanism to fine-tune the differentiation of xylem cells in time and space. We also demonstrate a role for a linker histone variant in the regulation of a specific developmental process through interaction with a transcription factor, illustrating that plant linker histones have other functions beyond chromatin organization.

A Conserved Core of Programmed Cell Death Indicator Genes Discriminates Developmentally and Environmentally Induced Programmed Cell Death in Plants.

A plethora of diverse programmed cell death (PCD) processes has been described in living organisms. In animals and plants, different forms of PCD play crucial roles in development, immunity, and responses to the environment. While the molecular control of some animal PCD forms such as apoptosis is known in great detail, we still know comparatively little about the regulation of the diverse types of plant PCD. In part, this deficiency in molecular understanding is caused by the lack of reliable reporters to detect PCD processes. Here, we addressed this issue by using a combination of bioinformatics approaches to identify commonly regulated genes during diverse plant PCD processes in Arabidopsis (Arabidopsis thaliana). Our results indicate that the transcriptional signatures of developmentally controlled cell death are largely distinct from the ones associated with environmentally induced cell death. Moreover, different cases of developmental PCD share a set of cell death-associated genes. Most of these genes are evolutionary conserved within the green plant lineage, arguing for an evolutionary conserved core machinery of developmental PCD. Based on this information, we established an array of specific promoter-reporter lines for developmental PCD in Arabidopsis. These PCD indicators represent a powerful resource that can be used in addition to established morphological and biochemical methods to detect and analyze PCD processes in vivo and in planta.

Chloroplasts at work during plant innate immunity.

The major role played by chloroplasts during light harvesting, energy production, redox homeostasis, and retrograde signalling processes has been extensively characterized. Beyond the obvious link between chloroplast functions in primary metabolism and as providers of photosynthesis-derived carbon sources and energy, a growing body of evidence supports a central role for chloroplasts as integrators of environmental signals and, more particularly, as key defence organelles. Here, we review the importance of these organelles as primary sites for the biosynthesis and transmission of pro-defence signals during plant immune responses. In addition, we highlight interorganellar communication as a crucial process for amplification of the immune response. Finally, molecular strategies used by microbes to manipulate, directly or indirectly, the production/function of defence-related signalling molecules and subvert chloroplast-based defences are also discussed.

The rice resistance protein pair RGA4/RGA5 recognizes the Magnaporthe oryzae effectors AVR-Pia and AVR1-CO39 by direct binding.

Resistance (R) proteins recognize pathogen avirulence (Avr) proteins by direct or indirect binding and are multidomain proteins generally carrying a nucleotide binding (NB) and a leucine-rich repeat (LRR) domain. Two NB-LRR protein-coding genes from rice (Oryza sativa), RGA4 and RGA5, were found to be required for the recognition of the Magnaporthe oryzae effector AVR1-CO39. RGA4 and RGA5 also mediate recognition of the unrelated M. oryzae effector AVR-Pia, indicating that the corresponding R proteins possess dual recognition specificity. For RGA5, two alternative transcripts, RGA5-A and RGA5-B, were identified. Genetic analysis showed that only RGA5-A confers resistance, while RGA5-B is inactive. Yeast two-hybrid, coimmunoprecipitation, and fluorescence resonance energy transfer-fluorescence lifetime imaging experiments revealed direct binding of AVR-Pia and AVR1-CO39 to RGA5-A, providing evidence for the recognition of multiple Avr proteins by direct binding to a single R protein. Direct binding seems to be required for resistance as an inactive AVR-Pia allele did not bind RGA5-A. A small Avr interaction domain with homology to the Avr recognition domain in the rice R protein Pik-1 was identified in the C terminus of RGA5-A. This reveals a mode of Avr protein recognition through direct binding to a novel, non-LRR interaction domain.

An atypical kinase under balancing selection confers broad-spectrum disease resistance in Arabidopsis.

The failure of gene-for-gene resistance traits to provide durable and broad-spectrum resistance in an agricultural context has led to the search for genes underlying quantitative resistance in plants. Such genes have been identified in only a few cases, all for fungal or nematode resistance, and encode diverse molecular functions. However, an understanding of the molecular mechanisms of quantitative resistance variation to other enemies and the associated evolutionary forces shaping this variation remain largely unknown. We report the identification, map-based cloning and functional validation of QRX3 (RKS1, Resistance related KinaSe 1), conferring broad-spectrum resistance to Xanthomonas campestris (Xc), a devastating worldwide bacterial vascular pathogen of crucifers. RKS1 encodes an atypical kinase that mediates a quantitative resistance mechanism in plants by restricting bacterial spread from the infection site. Nested Genome-Wide Association mapping revealed a major locus corresponding to an allelic series at RKS1 at the species level. An association between variation in resistance and RKS1 transcription was found using various transgenic lines as well as in natural accessions, suggesting that regulation of RKS1 expression is a major component of quantitative resistance to Xc. The co-existence of long lived RKS1 haplotypes in A. thaliana is shared with a variety of genes involved in pathogen recognition, suggesting common selective pressures. The identification of RKS1 constitutes a starting point for deciphering the mechanisms underlying broad spectrum quantitative disease resistance that is effective against a devastating and vascular crop pathogen. Because putative RKS1 orthologous have been found in other Brassica species, RKS1 provides an exciting opportunity for plant breeders to improve resistance to black rot in crops.