Tomato ARPC1 regulates trichome morphology and density and terpene biosynthesis.

MAIN CONCLUSION: Based on transcriptomic analysis of wild-type and mutant tomato plants, ARPC1 was found to be important for trichome formation and development and it plays a key role in terpene synthesis. Trichomes are protruding epidermal cells in plant species. They function as the first defense layer against biotic and abiotic stresses. Despite the essential role of tomato trichomes in defense against herbivores, the understanding of their development is still incomplete. Therefore, the aim of this study was to identify genes involved in trichome formation and morphology and terpene synthesis, using transcriptomic techniques. To achieve this, we examined leaf morphology and compared the expression levels of some putative genes involved in trichome formation between wild-type (WT) and hairless-3 (hl-3) tomato mutant. The hl-3 plants displayed swollen and distorted trichomes and reduced trichome density (type I and IV) and terpene synthesis compared with that of the WT plants. Gene expression analysis showed that Actin-Related Protein Component1 (ARPC1) was expressed more highly in the WT than in the hl-3 mutant, indicating its critical role in trichome morphology and density. Additionally, the expression of MYC1 and several terpene synthase genes (TPS9, 12, 20), which are involved in type VI trichome initiation and terpene synthesis, was lower in the hl-3 mutant than in the WT plants. Moreover, transformation of the hl-3 mutant with WT ARPC1 restored normal trichome structure and density, and terpene synthesis. Structural and amino acid sequence analysis showed that there was a missplicing mutation in the hl-3 mutant, which was responsible for the abnormal trichome structure and density, and impaired terpene synthesis. Overall, the findings of this study demonstrated that ARPC1 is involved in regulating trichome structure and terpene synthesis in tomato.

Effect of physical activity on the development and the resolution of nonalcoholic fatty liver in relation to body mass index.

BACKGROUND: Data on whether physical activity (PA) levels are related to nonalcoholic fatty liver disease (NAFLD) when considering body mass index (BMI) are scarce. We assessed whether PA affects the development or resolution of NAFLD in conjunction with BMI changes. METHODS: Overall, 130,144 participants who underwent health screening during 2011-2016 were enrolled. According to the PA level in the Korean version of the validated International PA Questionnaire Short Form, participants were classified into the inactive, active, and health-enhancing PA (HEPA) groups. RESULTS: In participants with increased BMI, the hazard ratio (HR) and 95% confidence interval after multivariable Cox hazard model for incident NAFLD was 0.97 (0.94-1.01) in the active group and 0.94 (0.89-0.99) in the HEPA group, whereas that for NAFLD resolution was 1.03 (0.92-1.16) and 1.04 (0.88-1.23) (reference: inactive group). With increased BMI, high PA affected only new incident NAFLD. PA enhancement or maintenance of sufficient PA prevented new incident NAFLD. In participants with decreased BMI, the HRs were 0.98 (0.90-1.07) and 0.88 (0.78-0.99) for incident NAFLD and 1.07 (0.98-1.17) and 1.33 (1.18-1.49) for NAFLD resolution in the active and HEPA groups, respectively. With decreased BMI, high PA reduced incident NAFLD and increased NAFLD resolution. Maintenance of sufficient PA led to a considerable resolution of NAFLD. CONCLUSION: In this large longitudinal study, PA prevented incident NAFLD regardless of BMI changes. For NAFLD resolution, sufficient PA was essential along with BMI decrease. Maintaining sufficient PA or increasing the PA level is crucial for NAFLD prevention or resolution.

SlHair2 Regulates the Initiation and Elongation of Type I Trichomes on Tomato Leaves and Stems.

Trichomes are hair-like structures that are essential for abiotic and biotic stress responses. Tomato Hair (H), encoding a C2H2 zinc finger protein, was found to regulate the multicellular trichomes on stems. Here, we characterized Solyc10g078990 (hereafter Hair2, H2), its closest homolog, to examine whether it was involved in trichome development. The H2 gene was highly expressed in the leaves, and its protein contained a single C2H2 domain and was localized to the nucleus. The number and length of type I trichomes on the leaves and stems of knock-out h2 plants were reduced when compared to the wild-type, while overexpression increased their number and length. An auto-activation test with various truncated forms of H2 using yeast two-hybrid (Y2H) suggested that H2 acts as a transcriptional regulator or co-activator and that its N-terminal region is important for auto-activation. Y2H and pull-down analyses showed that H2 interacts with Woolly (Wo), which regulates the development of type I trichomes in tomato. Luciferase complementation imaging assays confirmed that they had direct interactions, implying that H2 and Wo function together to regulate the development of trichomes. These results suggest that H2 has a role in the initiation and elongation of type I trichomes in tomato.

Effects of Age, Sex, and Obesity on N-Terminal Pro B-Type Natriuretic Peptide Concentrations in the General Population.

BACKGROUND: Data regarding complex relationships between age, sex, obesity and N-terminal pro B-type natriuretic peptide (NT-proBNP) remain scarce. Thus, we investigated sex-specific associations of obesity and NT-proBNP levels among adults in the general healthy population in Korea.Methods and Results:The associations of age, sex and obesity-associated parameters (waist circumference [WC], body mass index [BMI] and body weight) with NT-proBNP were analyzed in 39,937 healthy adult participants. Multivariable regression models adjusted for factors known to affect NT-proBNP were used to identify associations between NT-proBNP and obesity-related parameters. NT-proBNP levels were higher in females than males. Older age was also associated with higher NT-proBNP levels in the overall population (P<0.001). When accounting for age in multivariable linear regression models, there was a strong inverse association between WC, BMI, and NT-proBNP in females and a weaker inverse association in males, with a significant difference between the sexes (P interaction <0.001). After adjusting for the effects of WC and BMI on each other, abdominal obesity was associated with lower NT-proBNP levels in females but not males (P interaction <0.001). CONCLUSIONS: In this large sample of young and healthy Asians, younger age, male sex, and increases in obesity-related parameters were related to lower levels of NT-proBNP. Further comprehensive studies are needed to understand the factors affecting NT-proBNP levels in different populations.

Relationship between alcohol consumption and insulin resistance measured using the homeostatic model assessment for insulin resistance: A retrospective cohort study of 280,194 people.

BACKGROUND AND AIM: Alcohol consumption causes metabolic disorders and is a known risk factor for cardiovascular disease. However, some studies suggested that low level alcohol consumption improves insulin resistance. We evaluated the effects of alcohol consumption on insulin resistance using the homeostatic model assessment for insulin resistance (HOMA-IR). METHODS AND RESULTS: This study included 280,194 people without diabetes who underwent comprehensive health examinations more than twice between 2011 and 2018. The levels of alcohol intake were obtained through a self-questionnaire. All subjects were divided into two groups based on the Korean standard cut-off value of HOMA-IR, 2.2. Cox proportional hazard analysis was used to assess the risk of insulin resistance according to alcohol consumption. The mean age of the study subjects was 38.2 years and 55.7% were men. During the follow-up period (median 4.13 years), HOMA-IR progressed from <2.2 to ≥2.2 in 64,443 subjects (23.0%) and improved from ≥2.2 to <2.2 in 21,673 subjects (7.7%). In the parametric survival analysis, alcohol consumption was associated with improvement of HOMA-IR (HR [95% CI], 1.09[1.03-1.14], 1.11[1.06-1.17] and 1.20[1.13-1.26], respectively). In the analysis classified according to changes in alcohol consumption amounts, increased alcohol consumption tended to prevent the progression of HOMA-IR (0.97[0.96-0.99]; p = 0.004). However, the association between the changes in alcohol consumption amounts and improvement of HOMA-IR was not statistically significant. CONCLUSION: This retrospective observational study has shown that alcohol consumption can improve insulin resistance and increased alcohol consumption amounts may have preventive effects on the progression of HOMA-IR compared to the baseline level.

Evaluation of Cure Depth and Geometrical Overgrowth Depending on Zirconia Volume Fraction Using Digital Light Processing.

The optical properties of zirconia photopolymer suspension for DLP (Digital Light Processing) were evaluated. The light source and intensity were set to 395 nm and 30 mW/cm². Experimental groups were divided into 48, 50, 52, 54, 56 and 58 vol% according to the zirconia volume fraction. The cure depth of all groups was at least 47.35 um when cured for 1 sec, which was higher than layer parameter values of the 3D printer. The geometrical overgrowth showed 28.55% at 48 vol% and 36.94% at 58 vol%. As the volume fraction of zirconia increased, the geometrical overgrowth increased and the cure depth reduced.

Relationship Between Cotinine-Verified Smoking Status and Incidence of Hypertension in 74,743 Korean Adults.

BACKGROUND: The relationship between chronic smoking and hypertension (HTN) is inconclusive in previous studies, which were mainly based on self-reported smoking status. The aim of this study was to evaluate the association of cotinine-verified smoking status with incident HTN.Methods and Results:A total of 74,743 participants (43,104 men; age 38±5.4 years) were included in the study, with a mean follow-up period of 29 months. Individuals were divided into 4 groups on the basis of their cotinine-verified smoking status at baseline and at follow-up (never-smoking, new-smoking, former-smoking, and sustained-smoking). The incidence rate of HTN in the never-smoking, new-smoking, former-smoking, and sustained-smoking groups was 8.2%, 7.6%, 10.1%, and 8.7% for men and 1.8%, 2.5%, 1.5%, and 2.2% for women, respectively. In a multivariate Cox-hazard regression analysis adjusted for the variables with a univariate relationship, new-smoking and sustained-smoking had decreased relative risks (RRs) for incident HTN compared with never-smoking (RR [95% CI], 0.75 [0.58, 0.96] for new-smoking and 0.82 [0.74, 0.90] for sustained-smoking). Cotinine-verified current smoking at baseline was also inversely associated with incident HTN compared with cotinine-verified never-smoking at baseline (0.91 [0.84, 0.98]). These results remained significant only in men, although there was no sex interaction. CONCLUSIONS: This longitudinal study showed that cotinine-verified new-smoking and sustained-smoking decreased the risk for incident HTN, especially in men, compared with never-smoking.

Association between cotinine-verified smoking status and hypertension in 167,868 Korean adults.

PURPOSE: Previous studies showed inconsistent results concerning the relationship between chronic smoking and blood pressure. Most of the studies involved self-reported smoking status. This study was performed to evaluate the association of urinary cotinine or self-reported smoking status with hypertension and blood pressure in Korean adults. MATERIALS AND METHODS: Among individuals enrolled in the Kangbuk Samsung Health Study and Kangbuk Samsung Cohort Study, 167,868 participants (men, 55.7%; age, 37.5 ± 6.9 years) between 2011 and 2013 who had urinary cotinine measurements were included. Individuals with urinary cotinine levels ≥50 ng/mL were defined as cotinine-verified current smokers. RESULTS: The prevalence of hypertension and cotinine-verified current smokers in the overall population was 6.8% and 22.7%, respectively (10.0% in men and 2.8% in women for hypertension: 37.7% in men and 3.9% in women for cotinine-verified current smokers). In a multivariate regression analysis adjusted for age, sex, body mass index, waist circumference, alcohol drinking, vigorous exercise, and diabetes, cotinine-verified current smoking was associated with lower prevalence of hypertension compared with cotinine-verified never smoking (OR[95% CI], 0.79 [0.75, 0.84]). Log-transformed cotinine levels and unobserved smoking were negatively associated with hypertension, respectively (0.96 [0.96, 0.97] and 0.55 [0.39, 0.79]). In a multivariate linear regression analysis, the cotinine-verified current smoking was inversely associated with systolic and diastolic blood pressure (BP) (regression coefficient[95% CI], -1.23[-1.39, -1.07] for systolic BP and -0.71 [-0.84, -0.58] for diastolic BP). In subgroup analyses according to sex, the inverse associations between cotinine-verified current smoking and hypertension were observed only in men. CONCLUSIONS: This large observational study showed that cotinine-verified current smoking and unobserved smoking were inversely associated with hypertension in Korean adults, especially only in men.

Molecular cloning of the tomato Hairless gene implicates actin dynamics in trichome-mediated defense and mechanical properties of stem tissue.

Trichomes are epidermal structures that provide a first line of defense against arthropod herbivores. The recessive hairless (hl) mutation in tomato (Solanum lycopersicum L.) causes severe distortion of trichomes on all aerial tissues, impairs the accumulation of sesquiterpene and polyphenolic compounds in glandular trichomes, and compromises resistance to the specialist herbivore Manduca sexta Here, we demonstrate that the tomato Hl gene encodes a subunit (SRA1) of the highly conserved WAVE regulatory complex that controls nucleation of actin filaments in a wide range of eukaryotic cells. The tomato SRA1 gene spans a 42-kb region containing both Solyc11g013280 and Solyc11g013290 The hl mutation corresponds to a complex 3-kb deletion that removes the last exon of the gene. Expression of a wild-type SRA1 cDNA in the hl mutant background restored normal trichome development, accumulation of glandular trichome-derived metabolites, and resistance to insect herbivory. These findings establish a role for SRA1 in the development of tomato trichomes and also implicate the actin-cytoskeleton network in cytosolic control of specialized metabolism for plant defense. We also show that the brittleness of hl mutant stems is associated with altered mechanical and cell morphological properties of stem tissue, and demonstrate that this defect is directly linked to the mutation in SRA1.

Fine mapping and identification of candidate genes for the sy-2 locus in a temperature-sensitive chili pepper (Capsicum chinense).

KEY MESSAGE: The sy - 2 temperature-sensitive gene from Capsicum chinense was fine mapped to a 138.8-kb region at the distal portion of pepper chromosome 1. Based on expression analyses, two putative F-box genes were identified as sy - 2 candidate genes. Seychelles-2 ('sy-2') is a temperature-sensitive natural mutant of Capsicum chinense, which exhibits an abnormal leaf phenotype when grown at temperatures below 24 °C. We previously showed that the sy-2 phenotype is controlled by a single recessive gene, sy-2, located on pepper chromosome 1. In this study, a high-resolution genetic and physical map for the sy-2 locus was constructed using two individual F2 mapping populations derived from a cross between C. chinense mutant 'sy-2' and wild-type 'No. 3341'. The sy-2 gene was fine mapped to a 138.8-kb region between markers SNP 5-5 and SNP 3-8 at the distal portion of chromosome 1, based on comparative genomic analysis and genomic information from pepper. The sy-2 target region was predicted to contain 27 genes. Expression analysis of these predicted genes showed a differential expression pattern for ORF10 and ORF20 between mutant and wild-type plants; with both having significantly lower expression in 'sy-2' than in wild-type plants. In addition, the coding sequences of both ORF10 and ORF20 contained single nucleotide polymorphisms (SNPs) causing amino acid changes, which may have important functional consequences. ORF10 and ORF20 are predicted to encode F-box proteins, which are components of the SCF complex. Based on the differential expression pattern and the presence of nonsynonymous SNPs, we suggest that these two putative F-box genes are most likely responsible for the temperature-sensitive phenotypes in pepper. Further investigation of these genes may enable a better understanding of the molecular mechanisms of low temperature sensitivity in plants.

Determination of residues responsible for substrate and product specificity of Solanum habrochaites short-chain cis-prenyltransferases.

Isoprenoids are diverse compounds that have their biosynthetic origin in the initial condensation of isopentenyl diphosphate and dimethylallyl diphosphate to form C10 prenyl diphosphates that can be elongated by the addition of subsequent isopentenyl diphosphate units. These reactions are catalyzed by either cis-prenyltransferases (CPTs) or trans-prenyltransferases. The synthesis of volatile terpenes in plants typically proceeds through either geranyl diphosphate (C10) or trans-farnesyl diphosphate (C15), to yield monoterpenes and sesquiterpenes, respectively. However, terpene biosynthesis in glandular trichomes of tomato (Solanum lycopersicum) and related wild relatives also occurs via the cis-substrates neryl diphosphate (NPP) and 2Z,6Z-farnesyl diphosphate (Z,Z-FPP). NPP and Z,Z-FPP are synthesized by neryl diphosphate synthase1 (NDPS1) and Z,Z-farnesyl diphosphate synthase (zFPS), which are encoded by the orthologous CPT1 locus in tomato and Solanum habrochaites, respectively. In this study, comparative sequence analysis of NDPS1 and zFPS enzymes from S. habrochaites accessions that synthesize either monoterpenes or sesquiterpenes was performed to identify amino acid residues that correlate with the ability to synthesize NPP or Z,Z-FPP. Subsequent structural modeling, coupled with site-directed mutagenesis, highlighted the importance of four amino acids located within conserved domain II of CPT enzymes that form part of the second α-helix, for determining substrate and product specificity of these enzymes. In particular, the relative positioning of aromatic amino acid residues at positions 100 and 107 determines the ability of these enzymes to synthesize NPP or Z,Z-FPP. This study provides insight into the biochemical evolution of terpene biosynthesis in the glandular trichomes of Solanum species.

The flavonoid biosynthetic enzyme chalcone isomerase modulates terpenoid production in glandular trichomes of tomato.

Flavonoids and terpenoids are derived from distinct metabolic pathways but nevertheless serve complementary roles in mediating plant interactions with the environment. Here, we show that glandular trichomes of the anthocyanin free (af) mutant of cultivated tomato (Solanum lycopersicum) fail to accumulate both flavonoids and terpenoids. This pleiotropic metabolic deficiency was associated with loss of resistance to native populations of coleopteran herbivores under field conditions. We demonstrate that Af encodes an isoform (SlCHI1) of the flavonoid biosynthetic enzyme chalcone isomerase (CHI), which catalyzes the conversion of naringenin chalcone to naringenin and is strictly required for flavonoid production in multiple tissues of tomato. Expression of the wild-type SlCHI1 gene from its native promoter complemented the anthocyanin deficiency in af. Unexpectedly, the SlCHI1 transgene also complemented the defect in terpenoid production in glandular trichomes. Our results establish a key role for SlCHI1 in flavonoid production in tomato and reveal a link between CHI1 and terpenoid production. Metabolic coordination of the flavonoid and terpenoid pathways may serve to optimize the function of trichome glands in dynamic environments.

Optically pumped GaN vertical cavity surface emitting laser with high index-contrast nanoporous distributed Bragg reflector.

Laser operation of a GaN vertical cavity surface emitting laser (VCSEL) is demonstrated under optical pumping with a nanoporous distributed Bragg reflector (DBR). High reflectivity, approaching 100%, is obtained due to the high index-contrast of the nanoporous DBR. The VCSEL system exhibits low threshold power density due to the formation of high Q-factor cavity, which shows the potential of nanoporous medium for optical devices.

Association between brachial-ankle pulse wave velocity and progression of coronary artery calcium: a prospective cohort study.

BACKGROUND: Few studies have investigated the association between coronary artery calcium (CAC) progression and arterial stiffness measured by brachial-ankle pulse wave velocity (baPWV). We examined the influence of the severity of baseline baPWV on CAC progression in a large prospective cohort. METHODS: A total of 1600 subjects who voluntarily participated in a comprehensive health-screening program between March 2010 and December 2013 and had baseline baPWV as well as CAC on baseline and serial follow-up computed tomography performed approximately 2.7 ± 0.5 years apart were enrolled in the study. RESULTS: A total of 1124 subjects were included in the analysis (1067 men; mean age, 43.6 ± 5.1 years). An increased CAC score was found in 318 subjects (28.3%) during the follow-up period. Baseline higher baPWV was significantly correlated with CAC progression, especially in subjects with third- and fourth-quartile values (adjusted odds ratio [OR] 2.04; 95% confidence interval [CI] 1.33-3.15 and OR 2.14; 95% CI 1.34-3.41, respectively) compared with the lowest-quartile values (P for trend <0.001). A similar effect was observed in diabetic subjects. Among the 835 subjects with a baseline CAC score = 0, progression to CAC score >0 was associated with male sex, diabetes, and higher baPWV. However, among the 289 individuals with a baseline CAC score >0, only the presence of CAC itself was predictive of CAC progression. CONCLUSIONS: Higher arterial stiffness measured by baPWV could be significantly associated with CAC progression.

Echocardiographic epicardial fat thickness is associated with coronary artery calcification - results from the CAESAR study.

BACKGROUND: Few studies have addressed the relationship between echocardiographic epicardial fat thickness (EFT) and coronary artery calcification in an apparently healthy Asian population, and those that have, are inconsistent. METHODS AND RESULTS: A total of 2,299 individuals (1,871 men; mean age, 45±8.9 years) were enrolled in the CArdiometabolic risk, Epicardial fat, and Subclinical Atherosclerosis Registry (CAESAR) study and underwent CT for measurement of coronary artery calcium score (CACS) and echocardiography for EFT. According to EFT quartiles, the prevalence of CAC >0 was 8.3%, 16.8%, 24.6%, and 28.3% in the lowest, second, third, and highest EFT quartiles, respectively (P<0.001). On multivariate logistic regression after adjusting for variables with a univariate relationship (P<0.05), the second, third, and highest quartile groups of EFT had higher odds ratios (OR) for the presence of CAC compared with those of the lowest quartile (OR, 1.634; 95% confidence interval (CI): 0.940-2.839; 1.762, 1.019-3.048; and 1.924, 1.107-3.342, respectively), and the increase in absolute EFT was also independently associated with higher OR for the presence of CAC (1.842; 95% CI: 1.057-3.208, P=0.031). Moreover, increasing absolute EFT was associated with increasing CACS on multivariate linear regression (standardized ß=0.081, P=0.005). CONCLUSIONS: There was an independent relationship between EFT and coronary artery calcification in Korean adults, suggesting that echocardiographic EFT might be an easily accessible tool for early detection of subclinical coronary atherosclerosis.

Elevated production of 3-hydroxypropionic acid by metabolic engineering of the glycerol metabolism in Escherichia coli.

3-Hydroxypropionic acid (3-HP) is a renewable-based platform chemical which may be used to produce a wide range of chemicals including acrylic acid, 1,3-propanediol, and acrylamide. Commercialization of microbial 3-HP production from glycerol, which is produced inexpensively as a by-product of biodiesel production, could be expedited when global biodiesel production increases significantly. For enhancing 3-HP production, this study aimed to investigate metabolic engineering strategies towards eliminating by-products of 3-HP as well as optimizing the glycerol metabolism. The removal of genes involved in the generation of major by-products of 3-HP including acetate and 1,3-propanediol increased both 3-HP production level (28.1g/L) and its average yield (0.217g/g). Optimization of l-arabinose inducible expression of glycerol kinase GlpK, which catalyzes the conversion of glycerol to glycerol-3-phosphate, was also made to increase the metabolic flow from glycerol to 3-HP. To activate the whole glycerol metabolism towards 3-HP, the regulatory factor repressing the utilization of glycerol in Escherichia coli, encoded by glpR was eliminated by knocking-out in its chromosomal DNA. The resulting strain showed a significant improvement in the glycerol utilization rate as well as 3-HP titer (40.5g/L). The transcriptional analysis of glpR deletion mutant revealed the poor expression of glycerol facilitator GlpF, which is involved in glycerol transport in the cell. Additional expression of glpF in the glpR deletion mutant successfully led to an increase in 3-HP production (42.1g/L) and an average yield (0.268g/g).

Tomato Male sterile 1035 is essential for pollen development and meiosis in anthers.

Male fertility in flowering plants depends on proper cellular differentiation in anthers. Meiosis and tapetum development are particularly important processes in pollen production. In this study, we showed that the tomato male sterile (ms10(35)) mutant of cultivated tomato (Solanum lycopersicum) exhibited dysfunctional meiosis and an abnormal tapetum during anther development, resulting in no pollen production. We demonstrated that Ms10(35) encodes a basic helix-loop-helix transcription factor that is specifically expressed in meiocyte and tapetal tissue from pre-meiotic to tetrad stages. Transgenic expression of the Ms10(35) gene from its native promoter complemented the male sterility of the ms10(35) mutant. In addition, RNA-sequencing-based transcriptome analysis revealed that Ms10(35) regulates 246 genes involved in anther development processes such as meiosis, tapetum development, cell-wall degradation, pollen wall formation, transport, and lipid metabolism. Our results indicate that Ms10(35) plays key roles in regulating both meiosis and programmed cell death of the tapetum during microsporogenesis.

Combined use of bulked segregant analysis and microarrays reveals SNP markers pinpointing a major QTL for resistance to Phytophthora capsici in pepper.

KEY MESSAGE: Bulked segregant analysis (BSA) using Affymetrix GeneChips revealed candidate genes underlying the major QTL for Phytophthora capsici resistance in Capsicum. Using the candidate genes, reliable markers for Phytophthora resistance were developed and validated. Phytophthora capsici L. is one of the most destructive pathogens of pepper (Capsicum spp.). Resistance of pepper against P. capsici is controlled by quantitative trait loci (QTL), including a major QTL on chromosome 5 that is the predominant contributor to resistance. Here, to maximize the effect of this QTL and study its underlying genes, an F2 population and recombinant inbred lines were inoculated with P. capsici strain JHAI1-7 zoospores at a low concentration (3 × 10(3)/mL). Resistance phenotype segregation ratios for the populations fit a 3:1 and 1:1 (resistant:susceptible) segregation model, respectively, consistent with a single dominant gene model. Bulked segregant analysis (BSA) using Affymetrix GeneChips revealed a single position polymorphism (SPP) marker mapping to the major QTL. When this SPP marker (Phyto5SAR) together with other SNP markers located on chromosome 5 was used to confirm the position of the major QTL, Phyto5SAR showed the highest LOD value at the QTL. A scaffold sequence (scaffold194) containing Phyto5SAR was identified from the C. annuum genome database. The scaffold contained two putative NBS-LRR genes and one SAR 8.2A gene as candidates for contributing to P. capsici resistance. Markers linked to these genes were developed and validated by testing 100 F1 commercial cultivars. Among the markers, Phyto5NBS1 showed about 90% accuracy in predicting resistance phenotypes to a low-virulence P. capsici isolate. These results suggest that Phyto5NBS1 is a reliable marker for P. capsici resistance and can be used for identification of a gene(s) underlying the major QTL on chromosome 5.

Jasmonate-triggered plant immunity.

The plant hormone jasmonate (JA) exerts direct control over the production of chemical defense compounds that confer resistance to a remarkable spectrum of plant-associated organisms, ranging from microbial pathogens to vertebrate herbivores. The underlying mechanism of JA-triggered immunity (JATI) can be conceptualized as a multi-stage signal transduction cascade involving: i) pattern recognition receptors (PRRs) that couple the perception of danger signals to rapid synthesis of bioactive JA; ii) an evolutionarily conserved JA signaling module that links fluctuating JA levels to changes in the abundance of transcriptional repressor proteins; and iii) activation (de-repression) of transcription factors that orchestrate the expression of myriad chemical and morphological defense traits. Multiple negative feedback loops act in concert to restrain the duration and amplitude of defense responses, presumably to mitigate potential fitness costs of JATI. The convergence of diverse plant- and non-plant-derived signals on the core JA module indicates that JATI is a general response to perceived danger. However, the modular structure of JATI may accommodate attacker-specific defense responses through evolutionary innovation of PRRs (inputs) and defense traits (outputs). The efficacy of JATI as a defense strategy is highlighted by its capacity to shape natural populations of plant attackers, as well as the propensity of plant-associated organisms to subvert or otherwise manipulate JA signaling. As both a cellular hub for integrating informational cues from the environment and a common target of pathogen effectors, the core JA module provides a focal point for understanding immune system networks and the evolution of chemical diversity in the plant kingdom.