Frequency of a natural truncated allele of MdMLO19 in the germplasm of Malus domestica.

Podosphaera leucotricha is the causal agent of powdery mildew (PM) in apple. To reduce the amount of fungicides required to control this pathogen, the development of resistant apple cultivars should become a priority. Resistance to PM was achieved in various crops by knocking out specific members of the MLO gene family that are responsible for PM susceptibility (S-genes). In apple, the knockdown of MdMLO19 resulted in PM resistance. However, since gene silencing technologies such as RNAi are perceived unfavorably in Europe, a different approach that exploits this type of resistance is needed. This work evaluates the presence of non-functional naturally occurring alleles of MdMLO19 in apple germplasm. The screening of the re-sequencing data of 63 apple individuals led to the identification of 627 single nucleotide polymorphisms (SNPs) in five MLO genes (MdMLO5, MdMLO7, MdMLO11, MdMLO18, and MdMLO19), 127 of which were located in exons. The T-1201 insertion of a single nucleotide in MdMLO19 caused the formation of an early stop codon, resulting in a truncated protein lacking 185 amino acids, including the calmodulin-binding domain. The presence of the insertion was evaluated in 115 individuals. It was heterozygous in 64 and homozygous in 25. Twelve of the 25 individuals carrying the insertion in homozygosity were susceptible to PM. After barley, pea, cucumber, and tomato, apple would be the fifth species for which a natural non-functional mlo allele has been found.

Analysis of the genetic diversity and structure across a wide range of germplasm reveals prominent gene flow in apple at the European level.

BACKGROUND: The amount and structure of genetic diversity in dessert apple germplasm conserved at a European level is mostly unknown, since all diversity studies conducted in Europe until now have been performed on regional or national collections. Here, we applied a common set of 16 SSR markers to genotype more than 2,400 accessions across 14 collections representing three broad European geographic regions (North + East, West and South) with the aim to analyze the extent, distribution and structure of variation in the apple genetic resources in Europe. RESULTS: A Bayesian model-based clustering approach showed that diversity was organized in three groups, although these were only moderately differentiated (FST = 0.031). A nested Bayesian clustering approach allowed identification of subgroups which revealed internal patterns of substructure within the groups, allowing a finer delineation of the variation into eight subgroups (FST = 0.044). The first level of stratification revealed an asymmetric division of the germplasm among the three groups, and a clear association was found with the geographical regions of origin of the cultivars. The substructure revealed clear partitioning of genetic groups among countries, but also interesting associations between subgroups and breeding purposes of recent cultivars or particular usage such as cider production. Additional parentage analyses allowed us to identify both putative parents of more than 40 old and/or local cultivars giving interesting insights in the pedigree of some emblematic cultivars. CONCLUSIONS: The variation found at group and subgroup levels may reflect a combination of historical processes of migration/selection and adaptive factors to diverse agricultural environments that, together with genetic drift, have resulted in extensive genetic variation but limited population structure. The European dessert apple germplasm represents an important source of genetic diversity with a strong historical and patrimonial value. The present work thus constitutes a decisive step in the field of conservation genetics. Moreover, the obtained data can be used for defining a European apple core collection useful for further identification of genomic regions associated with commercially important horticultural traits in apple through genome-wide association studies.

Cognitive processing styles of children and adolescents with headache and back pain: a longitudinal epidemiological study.

BACKGROUND: Previous research has shown positive relationships between dysfunctional cognitive styles and different aspects of pain (eg, pain frequency). One goal of our longitudinal study was to investigate potential risk factors for the incidence of headache (HA) and back pain (BP). METHODS: In the first wave (2003), questionnaires were sent to 6,400 children between the ages of 9 and 14 years. Those who answered in wave 1 were contacted again every year (four survey waves in total: 2003-2006). The data presented are based on the children's self-reports in the second wave (2004) and third wave (2005). Potential risk factors (dysfunctional stress coping, pain catastrophizing, anxiety sensitivity, and somatosensory amplification) were collected in wave 2. Binary logistic regression analyses - for boys and girls - were performed to assess the predictive value of the risk factors for HA and BP in wave 3. RESULTS: In the comprehensive model, none of the examined variables predicted the incidence of HA. Anxiety sensitivity increased the risk that boys would report BP after 1 year by 50% and dysfunctional stress coping increased the risk by 40%. For girls, somatosensory amplification increased the risk of the incidence of BP 1 year later by 80%, whereas pain catastrophizing reduced the risk by 50%. CONCLUSION: In this incidence sample, the amount of variance explained by the psychological variables investigated was very small. Integrating this result with existing findings from cross-sectional studies suggests that dysfunctional cognitive processing styles may develop more as a consequence or a concomitant feature of BP or HA, but play a less important role in its initial development.

Sex-specific predictor analyses for the incidence of recurrent headaches in German schoolchildren.

OBJECTIVE: The aim of the present study was to identify psychosocial risk factors for the incidence of recurrent headache (HA) in children/adolescents (8-15 years). METHOD: In 2003 (Wave 1) a representative, population-based sample of 8800 parents was mailed a questionnaire. Those who took part were asked to participate again one year later (Wave 2). Of the parents originally contacted, 47.3% participated in both surveys. Potential risk factors concerning the areas 'school' and 'emotional and behavioural problems' were collected in Wave 1. Binary logistic regression analyses were performed to assess their predictive value for HA in Wave 2. RESULTS: Univariable regression analyses showed that for boys and girls most of the predictor variables influenced the incidence of recurrent HA, but only to a very low extent. When all variables were assessed jointly in a multivariable model, these factors lost their predictive power for boys. For girls, 'academic problems' and 'dysfunctional stress coping' were shown to increase the chance for the incidence of recurrent HA. DISCUSSION: In contrast to previous findings, school-related factors and emotional and behavioural problems failed to predict HA in boys, and only two factors appeared relevant with regard to girls. This might be due to the strict unidirectional design, which focussed exclusively on the incidence of HA.

Headache disorders in children and adolescents: their association with psychological, behavioral, and socio-environmental factors.

OBJECTIVE: This cross-sectional study on a randomly drawn population sample of children and adolescents (n = 3399; aged 9 to 15) aimed at the assessment of patterns of associations between psychosocial variables and primary headache disorders like migraine (MIG) or tension-type headache. A headache-free group served as a control. METHODS: Data on headache and psychological trait variables (eg, internalizing symptoms), behavioral factors (eg, physical activities), and socio-environmental factors (eg, life events) were gathered by questionnaire. Logistic regression analyses were conducted with headache types (MIG, tension-type, and non-classifiable headache) as dependent variables. RESULTS: The pattern of correlations was largely congruent between the headache disorders. Associations were closest regarding maladaptive psychological traits (in particular internalizing symptoms with an odds ratio > 4 regarding MIG) compared with socio-environmental factors and particularly the behavioral factors. Unfavorable psychological traits and socio-environmental strains demonstrated distinctly stronger associations with MIG than tension-type headache and explained more variance in the occurrence of pediatric headache disorders than parental headache. Sex-specific analyses showed similarities as well as differences regarding the correlations, and in general, the associations were stronger in girls than boys. CONCLUSIONS: A common path model as posited by several researchers in the field may explain the parallelism in biopsychosocial vulnerability regarding the different headache disorders.

The effects of sex and gender role on responses to pressure pain.

BACKGROUND: Several studies on experimental mechanical pain suggested a strong influence of sex demonstrating females to be more sensitive. We examined the hypothesis that not only sex but also gender role affects pain responsiveness and looked for mediators of this effect. METHOD: As indicators of pain the threshold the intensity and the unpleasantness of pressure stimuli were measured, as well as sensory and affective quality of pain. The gender role of 74 students was assessed by the Bem Sex Role Inventory (BSRI). Furthermore several psychological variables assumed to be potential mediators (catastrophising, fear of pain, depressive symptoms, pain coping) were obtained. RESULTS: ANOVA revealed significant main effects of sex in all pain variables except affective quality of pain. Contrary to our hypothesis gender role had no influence on pain responses, neither was there an interaction of sex and gender. Fear of pain just missed the significance level identifying it as mediator of the sex effect on affective pain. CONCLUSIONS: In summary, our study corroborated previous findings that women are more responsive to mechanical pain stimuli with effect sizes being medium to large, whereas gender role did not predict any of the assessed pain parameters. No convincing evidence was found that the influence of sex is predominantly mediated by psychological characteristics of the individual.

Multiple pains in children and adolescents: a risk factor analysis in a longitudinal study.

OBJECTIVE: The aim of the study was to ascertain the prevalence of multiple pains (MPs) and detect psychosocial risk factors assessed 1 year previously. METHOD: MPs were defined by the number of sites where pain was reported to occur at least "sometimes" in a general population sample of 2,219 German youths. RESULTS: Two or more sites of recurrent pain were reported by 54% of the participants, whereas 27% reported no pains. Girls were much more prone to MPs than boys. Stability of MP was high in the two waves. Regression analysis revealed that prior MP, age, sex, internalizing/externalizing symptoms, and time spent with visual media explained 25% of the variance: the contribution of the psychosocial factors to the model was small. Separate analyses for boys and girls displayed different risk-factor profiles and a higher degree of predictability in girls. CONCLUSION: A supposedly biological disposition, namely pain vulnerability, being particularly high in girls, is assumed to build the basis of pains felt in various sites of the body. Further research is needed to corroborate and specify these assumptions.

Children in pain: recurrent back pain, abdominal pain, and headache in children and adolescents in a four-year-period.

OBJECTIVE: To analyze the development of recurrent pain in 3 body locations in children and adolescents (baseline age, 9 to 14 years) in a 4-year period. STUDY DESIGN: In a large population-based longitudinal epidemiological study data was collected through annual postal questionnaires (longitudinal, n = 2025). Descriptive statistics and generalized estimating equations were used. RESULTS: Girls were more likely to report recurrent pain, demonstrated a steeper development during the 4-year period, and reported multiple pain more often than boys. Younger children reported less recurrent pain, but displayed a steeper trend of increasing prevalence rates as they grew older. Older children illustrated a more stable development of recurrent pain and reported multiple pain more often. Disability experienced because of recurrent pain was related strongest to pain intensity. Stable patterns of pain were related to higher intensity and disability reports. The children experienced headache as the most disabling of the 3 pains. CONCLUSION: The results show that boys and girls report recurrent pain in different patterns in the years. To identify risk factors, analysis should be performed separately for boys and girls. Furthermore, it is recommended to include children before the age of 9 years in a prevention study.

Risk factors for headache in children.

BACKGROUND: 10% to 30% of all children worldwide suffer from headaches at least once a week, potentially constituting a serious health problem that may lead to impairment in multiple areas. Therefore, one aim of the epidemiological longitudinal study "Children, Adolescents, and Headache" (KiJuKo) is the study of potential risk factors for the development of recurrent headaches. METHODS: In the first survey (2003), questionnaires were sent to 8800 households with a child between 7 and 14 years of age. Three further surveys followed, one each year from 2004 to 2006. A number of predictors having to do with family characteristics and leisure activities were identified on the basis of the first survey and were then studied in the second survey (n = 2952) with respect to their influence on the new occurrence of headaches. RESULTS: The risk of developing recurrent headaches between the first and the second survey was elevated by a factor of approximately 1.8 for boys who experienced quarrels in the family more than once per week, and by a factor of 2.1 for boys who only "sometimes" had free time for themselves. The risk of developing recurrent headaches was 25% higher in girls whose parents' behavior towards the child positively or negatively reinforced the occurrence of headaches. CONCLUSIONS: These findings are in accordance with those of other studies showing that, for boys, the frequency of quarreling in the family and the extent of leisure time are major factors in the development of recurrent headaches. For girls, the manner in which the parents respond to the child's headache seems to be important.

Agreement of parents and children on characteristics of pediatric headache, other pains, somatic symptoms, and depressive symptoms in an epidemiologic study.

BACKGROUND: The objective of the present study was to assess the concordance between parent and child report regarding different domains of pediatric health, headache in particular. In addition, the influence of potential moderator variables on the agreement between parents and children was examined. METHODOLOGY: In an epidemiologic study on a randomly drawn sample of households with at least 1 child in the family between 7 and 14 years of age (community registries), various pediatric health disturbances (headache, other pains, somatic symptoms, and depression/anxiety) were assessed via both child (from the age of 9 y on) and parent report (n=3461). RESULTS: A relatively high parent-child agreement (sigmaM=0.61) was found regarding the variable headache frequency, whereas consensus regarding other pains was, for the most part, markedly lower. The lowest agreement (sigmaM=0.27) was found for depression/anxiety symptoms. A moderator analysis (with age, sex, and parental headache) between child and parent failed to reveal significant differences regarding the degree of agreement between the 2 data sources. Children reported more frequent and more severe symptoms in all health domains. CONCLUSION: The examined potential moderator variables did not elucidate processes underlying the differences in child and parent agreement. There is no convincing evidence that the children's appraisal is less valid than their parents'. In summary, parents' reports cannot be viewed as a substitute for children's reports in pediatric pain and health assessment. Instead, each perspective represents a unique subjective reality and as such, both are of importance for research on pediatric pain and other health variables.