Genetic and morphological characterization of United States tea (Camellia sinensis): insights into crop history, breeding strategies, and regional adaptability.

Multiple introductions of tea (Camellia sinensis) to the United States since the 1850s have resulted in US tea germplasm that are currently poorly characterized. To resolve questions concerning the relatedness and regional adaptability of US tea germplasm, 32 domestic individuals were evaluated using 10 InDel markers, and compared with a background population of 30 named and registered Chinese varieties of tea. The marker data were analyzed via a neighbor-joining cladistic tree derived from Nei's genetic distance, STRUCTURE, and Discriminant Analysis of Principal Components, which revealed four genetic groups. Nineteen individuals selected from the four groups were assessed for seven leaf traits, two floral descriptors, and leaf yield, to identify plants best adapted to Florida field conditions. Our analyses compared with available historical records led us to estimate the most likely provenance of some of the US individuals, to precisely identify tea plant material and to choose most diverse accessions for breeding tea improved for adaptability, yield and quality.

Finding the Gaps: An Assessment of Concepts, Skills, and Employer Expectations for Plant Pathology Foundational Courses.

Foundational plant pathology courses, taught at the undergraduate level, serve students from a wide array of disciplines, and for most will be the only plant pathology course taken. This work examined the content, skills, and delivery modes of undergraduate plant pathology courses at a national scale, and assessed employer expectations for these courses and for students entering the workforce with degrees in plant science-related disciplines. While content knowledge coverage among plant pathology courses was generally consistent and aligned well with employers' knowledge expectations, delivery modes and skill development components were more variable and less aligned. Significant gaps were found between skills expected by employers and those emphasized by instructors, particularly in the areas of general laboratory skills (e.g., media preparation, molecular techniques, microscopy, and competence with other lab equipment) and recognition of plant problems that are not caused by pathogens. Employers also emphasized the value of (and frequent lack of) critical soft skills, such as teamwork, adaptability, communication, writing, and critical thinking. Results of this study will provide a foundation for course and curriculum development and evaluations. Recommendations are also discussed for enhanced interactions among educators and employers outside of academia.

Cellulase activity as a mechanism for suppression of phytophthora root rot in mulches.

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml(-1) or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml(-1) significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml(-1). In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml(-1) with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml(-1) 2 weeks before planting yielded activity of 20.08 µmol glucose equivalents per gram of soil water (GE g(-1) aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 µmol GE g(-1) aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.