Real-Time PCR Assays for Races of the Spinach Fusarium Wilt Pathogen, Fusarium oxysporum f. sp. spinaciae.

Fusarium wilt of spinach, caused by Fusarium oxysporum f. sp. spinaciae, is a significant limitation for producers of vegetative spinach and spinach seed crops during warm temperatures and/or on acid soils. Identification of isolates of F. oxysporum f. sp. spinaciae, and distinction of isolates of the two known races, entails time-intensive pathogenicity tests. In this study, two real-time PCR assays were developed: one for a candidate effector gene common to both races of F. oxysporum f. sp. spinaciae, and another for a candidate effector gene unique to isolates of race 2. The assays were specific to isolates of F. oxysporum f. sp. spinaciae (n = 44) and isolates of race 2 (n = 23), respectively. Neither assay amplified DNA from 10 avirulent isolates of F. oxysporum associated with spinach, 57 isolates of other formae speciales and Fusarium spp., or 7 isolates of other spinach pathogens. When the assays were used to detect DNA extracted from spinach plants infected with an isolate of race 1, race 2, or a 1:1 mixture of both races, the amount of target DNA detected increased with increasing severity of wilt. Plants infected with one or both isolates could be distinguished based on the ratio in copy number for each target locus. The real-time PCR assays enable rapid diagnosis of Fusarium wilt of spinach and will facilitate research on the epidemiology and management of this disease, as well as surveys on the prevalence of this understudied pathogen in regions of spinach and/or spinach seed production.

Shedding Light on Races of the Spinach Fusarium Wilt Pathogen, Fusarium oxysporum f. sp. spinaciae.

Two pathogenicity groups of Fusarium oxysporum f. sp. spinaciae, the causal agent of Fusarium wilt of spinach (Spinacia oleracea), were described recently based on virulence of isolates on proprietary spinach inbreds. In this study, a wide range in severity of wilt was observed for 68 spinach cultivars inoculated with an isolate of each pathogenicity group, with 22 (32.4%) cultivars displaying differential responses to the isolates. In a second set of trials, seven spinach cultivars were inoculated with five isolates of each pathogenicity group. The cultivars had similar wilt responses to isolates within each group. In both sets of trials, the most severe wilt developed on cultivars inoculated with pathogenicity group 2 isolates when daylength was shorter and light intensity lower. To test whether light intensity exacerbates severity of Fusarium wilt, three spinach cultivars were inoculated with two isolates of each pathogenicity group and grown with or without shading. Shaded plants developed more severe wilt than nonshaded plants. This difference in wilt severity was greatest for plants inoculated with pathogenicity group 2 isolates. We propose naming isolates of pathogenicity groups 1 and 2 as races 1 and 2 of F. oxysporum f. sp. spinaciae, respectively, and recommend the cultivars Kiowa (susceptible to both races) and Magnetic (susceptible to race 2 and highly resistant to race 1) as differentials. Results of this study should help breeders screen spinach germplasm for resistance to both races of F. oxysporum f. sp. spinaciae.

Predictors of Satisfying and Impactful Clinical Shadowing Experiences for Underrepresented Minority High School Students Interested in Healthcare Careers.

INTRODUCTION: Diversity among healthcare professionals lags behind the increasing racial and ethnic diversity of the United States' population. Increasing diversity of the health professional workforce may be one strategy to influence healthcare disparities. This study sought to understand factors associated with highly satisfying and impactful clinical shadowing experiences among underrepresented minority (URM) students in a health professional development program for urban high school students. METHODS: We analyzed data from students' summer clinical shadowing experiences in 2016 and 2017. We sought to determine if preceptor factors (e.g. racial and gender concordance with students), or patient related variables (e.g. racial concordance with students, the volume of patients per session) were associated with overall satisfaction with shadowing, the desire to pursue a similar career as their preceptor, and viewing their preceptor as a role model. After each shadowing experience, students completed evaluation forms. Chi-square tests were used for data analysis. RESULTS: Over two summers, 65 high school juniors participated in an average of 14 half-day clinical shadowing sessions; 59 of these students identify as URMs. Among URM students, racial/ethnic concordance between preceptor and student was significantly associated with viewing the preceptor as a role model (p = 0.028). Witnessing a greater number of patient-provider encounters (≥five patients per session) was associated with higher satisfaction with the experience (p = 0.0002), and viewing the preceptor as a role model (p = 0.04). CONCLUSION: To increase diversity of the healthcare workforce, URM students need high volume patient-provider encounters. Racial and/or ethnic concordance of URM students and preceptors may provide for preferable role models.