Characterizing the Dynamics of Virulence and Fungicide Resistance of Phytophthora capsici in Michigan Vegetable Fields Reveals Loci Associated with Virulence.

The oomycete Phytophthora capsici is a destructive pathogen infecting more than 50 plant species and is one of the most serious threats to cucurbit production. Phytophthora blight caused by Phytophthora capsici can affect all plant growth stages, and fungicides and cultural controls are used to limit losses. Dissecting pathogen virulence and fungicide resistance can provide insights into pathogenic mechanisms and inform effective management practices to control P. capsici. In this study, we assessed virulence, mefenoxam sensitivity, and genetic diversity of nine P. capsici populations collected from Cucurbitaceae, Solanaceae, and Fabaceae host families in Michigan from 2002 to 2016. We developed 992 simple sequence repeats (SSRs) in the P. capsici genome and identified 60 SSRs located within or close to RXLR-class (Arginine-any amino acid-Leucine-Arginine) effectors and 29 SSRs within or close to effector CRN (CRinkling and Necrosis) family protein, which represent 62 RXLR and 34 putative CRNs. Population structure analysis shows that mefenoxam resistance was not associated with the year of collection, host type, or location, but there were significant differences in virulence among the populations. Using the general linear model and mixed linear model-based association analyses with all effector-related SSR markers, we identified four SSR markers significantly associated with at least one of the virulence-related parameters. Of these, one (Pce_SC18) was in a predicted CRN effector and had high identity with the putative PhCRN37 effector in the pathogen Plasmopara halstedii, which can be further verified for virulence identification in P. capsici.

Development and initial validation of the psychological capital scale for nurses in Chinese local context.

BACKGROUND: Psychological capital is affected by different cultures and professional characteristics and its constituent dimensions and evaluation tools are heterogeneous. There is a lack of measurements for assessing nurses' psychological capital considering nursing professional characteristics and Chinese cultural impacts. AIMS: To develop a psychological capital scale that conforms to the Chinese cultural background and the characteristics of nursing profession, and evaluate the preliminary validation of the Nurses Psychological Capital Scale. METHODS: Nurses were conveniently recruited from two tertiary hospitals, Hebei, China. The research process included three steps: item development (Delphi survey and pilot survey), scale development (item analysis and exploratory factor analysis), scale validation (reliability and validity test). RESULTS: Exploratory factor analysis and confirmatory factor analysis showed that the 43-item scale comprised three factors (work task-oriented psychological capital, interpersonal relationship-oriented psychological capital and learning development-oriented psychological capital). Exploratory factor analysis showed the factor loadings ranging from 0.460 to 1.029. Three factors explained 68.71% of the variance. Confirmatory factor analysis showed an adequate model fit (x2/df =2.839, RMR = 0.041, RMSEA = 0.078, IFI = 0.872, TLI = 0.863, CFI = 0.871, PNFI = 0.768). The Cronbach's α for the scale was 0.975. The item-level content validity index (I-CVI) was 0.83 ~ 1.00, scale-level average content validity index (S-CVI/Ave) was 0.988. CONCLUSION: The Nurse Psychological Capital Scale had good reliability and validity, which is a reliable evaluation measure for assessing psychological capital among nurses.

Self-efficacy and well-being in the association between caregiver burden and sleep quality among caregivers of elderly patients having multiple chronic conditions in rural China: a serial multiple mediation analysis.

BACKGROUND: Caregivers of elderly patients with multiple chronic conditions have heavy caregiver burden and poor sleep quality, which has an important impact on both caregivers and patients. This study aimed to examine among rural caregivers of elderly patients who have multiple chronic conditions in China, whether self-efficacy and well-being mediate the link between caregiver burden and sleep quality. METHODS: The study recruited 325 caregivers of elderly patients having multiple chronic conditions in rural China. Several measures including the Caregiver Burden Inventory (CBI), Athens Insomnia Scale (AIS), General Self-Efficacy Scale (GSES) and Index of Well-Being (IWB) were utilized to collect data. Structural equation modeling was employed to study the relationships among caregiver burden, sleep quality, self-efficacy, as well as well-being. RESULTS: Significant correlations were found between the measured variables (each p < 0.01). Self-efficacy and well-being acted as mediators in the link between caregiver burden and sleep quality, accounting for 10.94% and 15.63% of the total effect, respectively. In addition, self-efficacy and well-being had a serial multiple mediating effect in the association between caregiver burden and sleep quality, with this mediating pathway, explaining 9.93% of the total effect. CONCLUSIONS: Caregivers of elderly patients having multiple chronic conditions in rural China experienced poor sleep quality due to the caregiver burden. Self-efficacy and well-being had serial mediating roles on the relationship between caregiver burden and sleep quality. Effective interventions should be developed to improve self-efficacy and well-being of caregivers, reduce their caregiver burden and, eventually, improve their sleep quality.

Quality of life in cancer patients with different preferences for nurse spiritual therapeutics: The role of psychological capital.

AIM: To explore the status of quality of life and psychological capital and analyse the different effects of psychological capital on the quality of life of cancer patients with different preferences for nurse spiritual therapeutics. DESIGN: A cross-sectional survey was used. METHODS: Two hundred and eight cancer patients were recruited using convenience sampling from a tertiary Chinese hospital, between March and July 2019. Data on preferences for nurse spiritual therapeutics (PNST), psychological capital (PsyCap) and quality of life (QoL) were collected using paper questionnaires. Hierarchical multiple regression was employed to investigate the different influences of PsyCap on QoL of cancer patients with various levels of PNST. RESULTS: Compared with patients having high PNST, patients with mild-moderate PNST experienced lower self-efficacy, hope, optimism, PsyCap and social/family well-being. PsyCap significantly explained the variance on QoL of patients with various levels of PNST. Age, gender, presence of caregiver were significant factors influencing physical, social/family and emotional well-being of patients with high PNST. CONCLUSION: The present study demonstrates disparities in PsyCap and QoL between cancer patients with mild-moderate and high PNST. It is essential to be aware of the positive influences of PsyCap on QoL and develop effective interventions for patients to improve their QoL, especially for those with mild-moderate PNST. IMPACT: It is necessary to realize the benefits of PsyCap on QoL of cancer patients with various levels of PNST. Appropriate training for nurses needs to be developed to promote their spiritual care competencies. Moreover, supportive interventions should be developed for cancer patients to improve their PsyCap and QoL.

Associations between perceived overqualification, organisational commitment and work passion of nurses: A multicentre cross-sectional study.

AIM: To investigate the associations between perceived overqualification, organisational commitment and work passion of nurses. BACKGROUND: Few studies have considered the effects of perceived overqualification and organisational commitment on work passion of nurses, especially in developing countries. METHODS: This is a multicentre cross-sectional study. A total of 4511 nurses from eight tertiary hospitals were recruited. The Scale of Perceived OverQalification (SPOQ), the Organizational Commitment Scale (OCS) and the Work Passion Scale (WPS) were used to collect the data. Hierarchical multiple regression were employed. RESULTS: Perceived overqualification and organisational commitment were the main predictors for both harmonious and obsessive passions (each p < .001). The unique effect of organisational commitment (ßharmonious  = .608, ßobsessive  = .556) on work passion were six to eight times larger than these of perceived overqualification (ßharmonious = -.079, ßobsessive = .085). CONCLUSION: Our findings indicate that high perceived overqualification clearly reduces nurses' harmonious passion and increases their obsessive passion, whereas high organisational commitment significantly promotes nurses' harmonious and obsessive passions. IMPLICATIONS FOR NURSING MANAGEMENT: Nurse managers should distinguish the different effects of perceived overqualification and organisational commitment on work passion. Effective intervention should be developed to release nurses' potential abilities and improve their organisational commitment and work passion. Chinese Clinical Trial Registry: ChiCTR2100047974.

Associations between perceived overqualification, transformational leadership and burnout in nurses from intensive care units: A multicentre survey.

AIMS: To explore whether perceived overqualification increases the risk of burnout and whether transformational leadership negatively moderates this relationship. BACKGROUND: Perceived overqualification might contribute to burnout and lead to poor experience of transformational leadership, and transformational leadership might be associated with burnout. However, these relationships have not yet been confirmed. METHODS: A multicentre cross-sectional study. A total of 321 nurses from intensive care units were recruited from six tertiary hospitals. Scale of Perceived OverQualification, Transformational Leadership Questionnaire and emotional exhaustion subscale of the Maslach Burnout Inventory-General Survey were employed to collect the data. Hierarchical multiple regression and bootstrap resampling were applied to analyse the data. RESULTS: Burnout was positively associated with perceived overqualification and negatively associated with transformational leadership (each p < 0.05). Transformational leadership significantly mediated the relationship between perceived overqualification and burnout (b = -0.6389, 95% confidence interval: -0.8706, -0.4072). CONCLUSION: Our findings indicated that perceived overqualification and transformational leadership directly or indirectly affect burnout among nurses from intensive care units. IMPLICATIONS FOR NURSING MANAGERS: Personal and organizational-oriented interventions utilizing nurses' overall qualifications and implementing transformational leadership should be employed by nurse managers to alleviate burnout and promote the work performance of nurses from intensive care units.

Population Structure of a Worldwide Phytophthora palmivora Collection Suggests Lack of Host Specificity and Reduced Genetic Diversity in South America and the Caribbean.

Phytophthora palmivora (Butler) is a highly destructive plant pathogen that infects tropical hosts worldwide, many of which are economically important crops. Despite the broad host range and wide distribution, the pathogen has displayed a considerable amount of variation in morphological characters, including virulence. However, the genetic variability at a global level, which is critical to understand the center of origin and the potential pathway(s) of introduction, was unclear. Here, we mapped the genetic variation of P. palmivora using isolates representing four regions, 15 countries, and 14 host species. We designed a large set of simple sequence repeat markers from the P. palmivora genome and picked 17 selectively neutral markers to screen 98 P. palmivora isolates. We found that P. palmivora populations from our collection generally did not cluster according to host; rather, some isolates from North America were generally distinct from all other populations. Isolates from South America and the Caribbean clustered and appeared to share ancestry with isolates from Asia. Populations from North America and Asia were the most genetically diverse, while the South American and Caribbean populations exhibited similar reduced genetic diversity. The isolates collected in various plantations in Colombia did not show host or geographic specificity. Our study brought a further understanding of this important plant pathogen, although the determination for hypothesized source of origin, spread, and evolution would need further sampling. The genomic resources developed in this study would facilitate further studies on P. palmivora diagnostics and management.

Association between psychological capital and spiritual care competencies of clinical nurses: A multicentre cross-sectional study.

AIMS: To investigate the status of spiritual care competencies among clinical nurses and their relationships with psychological capital. BACKGROUND: Limited knowledge is about the influence of positive personal characteristics on nurses' spiritual care competencies. METHODS: A multicentre cross-sectional study. A total of 1717 nurses were recruited from nine separate Chinese hospitals. Online questionnaires were delivered through a local nursing association to assess socio-demographics, spiritual care competencies and psychological capital of nurses. RESULTS: Nurses had mild-to-moderate levels of spiritual care competencies and moderate levels of psychological capital. Psychological capital and its two metrics (self-efficacy and hope), spiritual care education, professional qualification and shift work were the main predictors of spiritual care competencies (each p < .05). CONCLUSION: The findings of the study show a positive relationship between psychological capital and spiritual care competencies of clinical nurses. Strengthening nurses' psychological capital could improve their spiritual care competencies. IMPLICATIONS FOR NURSING MANAGERS: Nurse managers and hospital administrators should better understand the value of psychological capital for nurses' capacity development. Effective interventions need to be implemented separately or combined with spiritual care education programmes to improve nurses' psychological capital and spiritual care competencies.

Resilience-based multifactorial model of depression among people who lost an only-child in China. / å¤±ç‹¬è€ æŠ‘éƒçš„å¿ƒç†å¼¹æ€§å¤šå› ç´ ä½œç”¨æ¨¡åž‹.

OBJECTIVES: There are almost one million families who lost their only child in China, and 65.6% of them had severe and long lasting depression and needed timely psycho-intervention. This study aims to explore the relationship among resilience and its influential factors, and to compare their effect on depression. METHODS: A total of 212 only-child loss person in 9 administrative regions in Changsha were assessed by using Connor-Davidson Resilience Scale, Zung Self-rating Depression Scale, Simplified Coping Style Questionnaire, Simplified Eysenck Personality Questionnaire, Social Support Rating Scale, and General Self-efficacy Scale. A hypothetical model was tested based on Kumpfer resilience framework and stress-coping theory. RESULTS: The influential factors of resilience were: positive coping (the total effect value was 0.480), support utilization (the total effect value was 0.359), neuroticism (the total effect value was -0.326), negative coping (the total effect value was 0.279), extraversion (the total effect value was 0.219), and objective support (the total effect value was 0.077). The process of individual-environment interaction showed a greater impact on resilience, which had a direct effect on depression (the total effect value was -0.344, 67.1%), and also indirect effect through self-efficacy (the total effect value was -0.169). The total effect of resilience accounted for 20.1% of the total effect of all variables. CONCLUSIONS: Resilience mainly impacts depression directly, and can negatively predict depression in only-child loss parents. Resilience, located before self-efficacy, is a significant stress mediating variables. Personality traits and support utilization indirectly impact resilience via negative and positive coping. The key to promote the reorganization of resilience is the process of individual-environmental interaction, involving support utilization, positive coping, and some sorts of negative coping strategies, which plays an important role in developing a resilience intervention program and can improve the depression of the only-child loss person.

Impact of WeChat-based 'three good things' on turnover intention and coping style in burnout nurses.

BACKGROUND: Few studies have considered functions of nurses' positive personality and behaviours on addressing their turnover intention. AIMS: To explore the effects of WeChat-based 'three good things' (3GT) on burnout nurses' turnover intention and coping styles. METHODS: A randomized controlled trial. 73 nurses were included in the intervention group (n = 33) and the control group (n = 40). The intervention group received WeChat-based 3GT. Turnover intention and coping style were measured before and after the intervention. RESULTS: WeChat-based 3GT effectively reduced turnover intention and negative coping style (each p < .05). Positive coping style was promoted after the intervention (p < .05). Time effects as well as intervention and time interactions were significant in turnover intention and negative coping style (each p < .05). CONCLUSION: Benefits of WeChat-based 3GT on turnover intention and coping style in burnout nurses were found. Nurses experienced lower levels of turnover intention and negative coping style and increased the usage of positive coping style after the intervention. IMPLICATIONS FOR NURSING MANAGEMENT: Nurse managers should incorporate 3GT intervention with popular social communication programmes to improve nurses' coping strategies towards clinical issues and maintain the stability of nursing teams.

A WeChat-based "Three Good Things" positive psychotherapy for the improvement of job performance and self-efficacy in nurses with burnout symptoms: A randomized controlled trial.

AIM: To evaluate the effects of a WeChat-based "Three Good Things" on job performance and self-efficacy of clinical nurses with burnout symptoms. BACKGROUND: Few studies have valued the impact of nurses' personal strengths and positive work environment on job performance, particularly in developing countries. METHODS: A randomized controlled trial. The intervention group (n = 33) participated in WeChat-based Three Good Things, while the control group (n = 40) did not. Data were collected prior to and immediately after the intervention. WeChat, a popular social software, provides several communicating and recording functions. RESULTS: The main intervention effects and interactions between time and intervention on job performance and self-efficacy were significant (each p < .05). The main time effects on self-efficacy were also significant (p < .05). The post-intervention scores for job performance and self-efficacy between the two groups were statistically different (each p < .05). The scores for job performance and self-efficacy of the intervention group were statistically different before and after the intervention (each p < .05). CONCLUSION: Three Good Things could significantly improve job performance and self-efficacy of nurses with burnout. IMPLICATIONS FOR NURSING MANAGEMENT: Nurse managers are recommended to include Three Good Things into their management systems to improve nurses' physical and mental health and work outcomes over the long term.

The effects of resilience and turnover intention on nurses' burnout: Findings from a comparative cross-sectional study.

AIMS AND OBJECTIVES: To investigate burnout among nurses from Australia and China and explore the effects of resilience and turnover intention on nurse burnout between the two countries. BACKGROUND: Nursing shortages and burnout have become serious problems worldwide in recent years. In both developed and developing countries, such as Australia and China, nurse burnout levels are high and therefore attract concern from nurse managers, hospital administrators, nurse educators and researchers. However, few studies have been conducted exploring the differences in burnout and its predictors between Australian and Chinese nurses, particularly investigating the differences in the effect sizes of the predictors. DESIGN: A comparative cross-sectional design was employed. METHODS: A total of 100 Australian nurses and 197 Chinese nurses participated in the study. Australian participants completed an online questionnaire, while Chinese participants completed a hardcopy questionnaire. Burnout, resilience and turnover intention were measured. RESULTS: Burnout was worse for Australian participants than Chinese participants. Only having turnover intention significantly predicted burnout in Australian participants, while low resilience, having turnover intention and low level of regular exercise strongly predicted burnout in Chinese participants. The effect size of turnover intention on burnout in the Australian group was almost twice that of the Chinese group. CONCLUSION: The findings of this study show that there are differences in burnout between Australian and Chinese nurses. The effects of resilience and turnover intention on burnout between the two groups are also identified. RELEVANCE TO CLINICAL PRACTICE: The differences in nurse burnout and the effects of resilience and turnover intention on burnout should be better understood by nurse managers from Australia and China. Moreover, developing effective strategies relevant to their own country to reduce nurse burnout is recommended.

An evaluation of a positive psychological intervention to reduce burnout among nurses.

This quasi-experimental study aimed to evaluate the positive psychological intervention of recording three good things on alleviating nurses' burnout. Eighty-seven nurses with burnout were recruited. Nurses in the study group recorded three good things using communication tool WeChat for six months, no records were made in the control group. After intervention, the score of exhaustion decreased considerably for nurses in the study group. Nurses recording three good things on average twice a week returned the lowest score of exhaustion. This intervention combined with appropriate surveillance and encouragement is recommended to reduce nurses' burnout and create a positive work environment.

[Research progress in the relationship between depression and survival outcome in patients with lung cancer].

In recent years, with the high incidence of lung cancer and mortality, the disease-relevant mental health problems such as depression began to attract attention. A growing number of studies have also begun to hypothesize and confirm the relationship between depression and survival or mortality in patients with lung cancer, and have made some progress in basic research, prospective cohort research and intervention research. In basic research, cancer can cause depression due to mediating the production of inflammatory factors, and the genotype of tumor epidermis growth factor receptor (EGFR) can explain the high mortality and risk of depression in patients with lung cancer from a certain point of view. Different studies in prospective cohort studies argue that depression is an important predictor of survival in patients with lung cancer and need to be further studied. In the aspect of intervention research, although some studies have confirmed the potential of antidepressants in anti-tumor oxidative therapy, there is no enough evidence in psychological intervention and drug intervention to prove their effectiveness in improving the survival outcome of lung cancer. In the future, it is necessary to further explore the possible mechanisms for antidepressants and psychological intervention to improve the survival time of the patients.

Burnout and its association with resilience in nurses: A cross-sectional study.

AIMS AND OBJECTIVES: To investigate the prevalence and extent of burnout on nurses and its association with personal resilience. BACKGROUND: With the worldwide shortage of nurses, nurse burnout is considered one of the main contributing factors and has been the focus of studies in recent years. Given the well-documented high level of burnout among nurses, resilience is expected to be a significant predictor of nurse burnout. The association between burnout and resilience has not previously been investigated extensively. DESIGN: A cross-sectional survey design was selected. METHODS: A total of 1,061 nurses from six separate three-level hospitals in Hunan Province, China, returned self-reported questionnaires from March-June 2015. Data were collected using a socio-demographic sheet, Maslach Burnout Inventory-General Survey and the Connor-Davidson Resilience Scale. RESULTS: Nurses experienced severe burnout symptoms and showed a moderate level of resilience. Three metrics of burnout had significantly negative correlations with the total score and following variables of resilience. Linear regression analysis showed resilience, especially strength, demographic characteristics (exercise, alcohol use and marital status) and job characteristics (income per month, ratio of patients to nurses, shift work and professional rank) were the main predictors of the three metrics of burnout. CONCLUSION: The findings of this study may help nurse managers and hospital administrators to have a better understanding of nurse burnout and resilience. The significantly negative relationship between burnout symptoms and resilience has been demonstrated, and this informs the role of resilience in influencing burnout. RELEVANCE TO CLINICAL PRACTICE: Adaptable and effective interventions for improving resilience are needed to relieve nurses' burnout and reduce workplace stress. Moreover, nurse managers and hospital administrators should establish an effective management system to cultivate a healthy workplace and adopt positive attitudes and harmonious relationships.

Exploring resilience in Chinese nurses: a cross-sectional study.

AIMS: To explore the state of resilience and its predictors among nurses in mainland China. BACKGROUND: Resilience is considered as an important ability to influence the prevention of job dissatisfaction and burnout. There are few studies on resilience in Chinese nurses, particularly investigating the predictors of resilience. METHODS: A cross-sectional survey was employed and 1061 nurses from six three-level hospitals in Hunan responded to participate in the study. Data were collected using self-reported questionnaires. RESULTS: Nurses experienced moderate levels of resilience and self-efficacy and tended to use a positive coping style. Multiple linear regression showed that a high level of self-efficacy and education, having a positive coping style rather than a negative coping style, exercising regularly and not using cigarettes predicted a high level of resilience (P < 0.01). CONCLUSION: This study shows a moderate level of resilience among nurses and suggests that a high level of self-efficacy and education, as well as having a positive coping style and choosing a healthy lifestyle may increase nurses' resilience. IMPLICATIONS FOR NURSING MANAGEMENT: Hospital administrators and nursing managers need to explore the resilience state among nurses and understand the predictors of resilience. Then, scientific and evidence-based interventions for improving resilience should be adopted.

[Mediation role of self-efficacy between social support and depression of only-child-lost people].

OBJECTIVE: To investigate the relationship between social support and depression of only-child-lost (OCL) people, and the mediation role of self-efficacy in this relationship. 
 Methods: By stratified cluster sampling, 214 OCL people were enrolled, with 80 males and 134 females, ages from 49 to 83 years old. They were assessed by General Self-Efficacy Scale, Social Support Rating Scale, and Self-rating Depression Scale.
 Results: Univariate analysis showed that there were significant differences in age groups (t=2.85, P<0.05), with or without spouse (t=5.62, P<0.05), family location (t=3.95, P<0.05), per capita monthly income (F=3.48, P<0.05) among the social support scores. There was significant difference between the per capita monthly income and self-efficacy scores in QCL people (F=5.46, P<0.05). Correlation analysis showed self-efficacy and social support were positively correlated (r=0.26, P<0.01). Self-efficacy (r=-0.59, P<0.01) and social support (r=-0.59, P<0.01) negatively correlated with depression in OCL people. Self-efficacy partially mediated the relationship between social support and depression.
 Conclusion: The person who is <60 years old, with spouse and the high per capita monthly income, and lives the rural area, would have high social support levels among QCL people. The person who has high per capita monthly income would have high self-efficacy. Self-efficacy is one of the direct prediction for depression, and plays an indirect role between social support and depression. Intervention of depression among OCL people could be applied to change their cognition, and to enhance their self-efficacy.

TILLING by sequencing to identify induced mutations in stress resistance genes of peanut (Arachis hypogaea).

BACKGROUND: Targeting Induced Local Lesions in Genomes (TILLING) is a powerful reverse genetics approach for functional genomics studies. We used high-throughput sequencing, combined with a two-dimensional pooling strategy, with either minimum read percentage with non-reference nucleotide or minimum variance multiplier as mutation prediction parameters, to detect genes related to abiotic and biotic stress resistances. In peanut, lipoxygenase genes were reported to be highly induced in mature seeds infected with Aspergillus spp., indicating their importance in plant-fungus interactions. Recent studies showed that phospholipase D (PLD) expression was elevated more quickly in drought sensitive lines than in drought tolerant lines of peanut. A newly discovered lipoxygenase (LOX) gene in peanut, along with two peanut PLD genes from previous publications were selected for TILLING. Additionally, two major allergen genes Ara h 1 and Ara h 2, and fatty acid desaturase AhFAD2, a gene which controls the ratio of oleic to linoleic acid in the seed, were also used in our study. The objectives of this research were to develop a suitable TILLING by sequencing method for this allotetraploid, and use this method to identify mutations induced in stress related genes. RESULTS: We screened a peanut root cDNA library and identified three candidate LOX genes. The gene AhLOX7 was selected for TILLING due to its high expression in seeds and roots. By screening 768 M2 lines from the TILLING population, four missense mutations were identified for AhLOX7, three missense mutations were identified for AhPLD, one missense and two silent mutations were identified for Ara h 1.01, three silent and five missense mutations were identified for Ara h 1.02, one missense mutation was identified for AhFAD2B, and one silent mutation was identified for Ara h 2.02. The overall mutation frequency was 1 SNP/1,066 kb. The SNP detection frequency for single copy genes was 1 SNP/344 kb and 1 SNP/3,028 kb for multiple copy genes. CONCLUSIONS: Our TILLING by sequencing approach is efficient to identify mutations in single and multi-copy genes. The mutations identified in our study can be used to further study gene function and have potential usefulness in breeding programs.

Transcriptome-enabled marker discovery and mapping of plastochron-related genes in Petunia spp.

BACKGROUND: Petunia (Petunia × hybrida), derived from a hybrid between P. axillaris and P. integrifolia, is one of the most economically important bedding plant crops and Petunia spp. serve as model systems for investigating the mechanisms underlying diverse mating systems and pollination syndromes. In addition, we have previously described genetic variation and quantitative trait loci (QTL) related to petunia development rate and morphology, which represent important breeding targets for the floriculture industry to improve crop production and performance. Despite the importance of petunia as a crop, the floriculture industry has been slow to adopt marker assisted selection to facilitate breeding strategies and there remains a limited availability of sequences and molecular markers from the genus compared to other economically important members of the Solanaceae family such as tomato, potato and pepper. RESULTS: Here we report the de novo assembly, annotation and characterization of transcriptomes from P. axillaris, P. exserta and P. integrifolia. Each transcriptome assembly was derived from five tissue libraries (callus, 3-week old seedlings, shoot apices, flowers of mixed developmental stages, and trichomes). A total of 74,573, 54,913, and 104,739 assembled transcripts were recovered from P. axillaris, P. exserta and P. integrifolia, respectively and following removal of multiple isoforms, 32,994 P. axillaris, 30,225 P. exserta, and 33,540 P. integrifolia high quality representative transcripts were extracted for annotation and expression analysis. The transcriptome data was mined for single nucleotide polymorphisms (SNP) and simple sequence repeat (SSR) markers, yielding 89,007 high quality SNPs and 2949 SSRs, respectively. 15,701 SNPs were computationally converted into user-friendly cleaved amplified polymorphic sequence (CAPS) markers and a subset of SNP and CAPS markers were experimentally verified. CAPS markers developed from plastochron-related homologous transcripts from P. axillaris were mapped in an interspecific Petunia population and evaluated for co-localization with QTL for development rate. CONCLUSIONS: The high quality of the three Petunia spp. transcriptomes coupled with the utility of the SNP data will serve as a resource for further exploration of genetic diversity within the genus and will facilitate efforts to develop genetic and physical maps to aid the identification of QTL associated with traits of interest.