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- Author or Editor: S. L. Kitto x
Spigelia marilandica, an herbaceous perennial native to the temperate eastern United States, has great potential for the sunny garden due to a fairly long flowering period-and long (3.5-5.5 cm) tubular corollas that are scarlet on the outside and yellowish within. Non-wild collected seeds were disinfested using conventional procedures, and after 8 wk at 4°C, four seeds germinated in vitro. Preliminary experiments examined seedling lines (# 1, 2, 5 and 6) and media (MS versus DKW.) Line 6 was found to be consistently more proliferative over a six month period. Trend analysis demonstrated no difference in total number of axillary shoots produced on full versus 1/2 MS media. MS-derived microcuttings were chlorotic but appeared to root better than DKW-derived microcuttings.
Pachysandra procumbens, the Allegheny spurge, is a native herbaceous perennial. Microcuttings were maintained in liquid MS medium in Magenta boxes with membrane rafts. A preliminary study looked at 1,2.5,5, and 10 mg BA/liter and 0 and 1 mg NAA/liter. Shootscultured with 5 or 10 mg BA/liter and no NAA produced significantly more axillary shoots. When shoots were cultured on media containing 5,10, 15, 20, or 25 mg BA/liter, trend analysis indicated significant linear and quadratic trends. Shoots proliferated similarly when cultured with 5 to 20 mg BA/liter. Non-fully expanded shoots proliferated significantly better compared to fully expanded shoots. After 6 weeks, microcuttings dipped in 500 or 1000 ppm IBA (50% ethanol) had produced significantly more roots of greater length compared to the control. Sixteen weeks after potting, rooted microcuttings potted in MetroMix 500, Promix BX, or a nursery mix (60% pine bark, 20% peat, 20% stone dust) had initiated significantly more shoots.
The course “Biotechnology: Science and Socioeconomic Issues” has used problem-based learning (PBL) during the last quarter of the course for the past 3 years. One of the challenges of using PBL in medium-sized and larger classes is finding a way to facilitate each group of students with a limited number of qualified facilitators while avoiding unmanageably large numbers of students per group. This past year (95F) the course had both a nonhonor's and an honor's section. The honor's section met an additional hour each week to learn about PBL and peer tutoring skills. Training students to be peer tutors was divided up into four parts: 1) the science behind PBL, 2) experience working through a previously developed case study, 3) development of a case study, and 4) peer tutoring case studies in the non-honor's section. We will discuss the process of training students to be effective peer tutors for PBL.
In this study, the pod development dynamics and culture response in lima bean (Phaselous lunatus L.) were investigated. The average percentage of flowers to form pins was 17.5%. Pin length and width (mm), and weight (g) were all highly correlated with the days after pollination (DAP), with correlation coefficients of 0.98, 0.99 and 0.97, respectively. Pods grew relatively faster between 12 and 20 DAP, and reached their maximum length at about 35 DAP. Explants from pods of 5, 10, 15, 20, 25 DAP were cultured onto B5 medium containing BA (2 mg/L), kinetin (0.5 mg/L), 2,4-D (1 mg/L) or NAA (1 mg/L), sucrose (5%), and agar (0.7%). Soft calli only formed from the cut region on the seed coat or the suspensor attachment site of 5 and 10 DAP seeds. The 15 DAP explants were cultured as embryos (cotyledons 2 mm in length), and no callus was observed on them after 30 days of culture when they became brown. Twenty and 25 DAP embryos initiated calli and/or organ-like structures on the abaxial surface of cotyledons or embryo axes after 20 days of culture.
An assay using in vivo-produced embryos, with and without tegmen, of monoembryonic ‘Temple’ tangor [Citrus sinensis (L.) Osbeck x C. reticulata Blanco) and polyembryonic ‘Troyer’ citrange (C. sinensis x Poncirus trifoliata Raf.) was developed to screen compounds as synthetic seed coats for in vitro-produced, asexual embryos. Of 8 compounds evaluated, Polyox WSR-N 750 proved to be the most suitable as a synthetic seed coat based on its film-forming ability, its ability to redissolve in water, and its nondeleterious effects on citrus embryos.
Cotyledons and embryonic axes of Pistacia vera L. `Kerman' were cultured on modified DKW or MS media. Cotyledonary petioles regenerated shoots when cultured on DKW medium supplemented with (in g/liter) 2.5 Zn(NO3)2, 0.48 H3BO3, 100 KNO3 and (in mg/liter) 1 BA, 0.01 IBA, 2 kinetin and 250 glutamine whether under light (80 μmol·m-2·s-1) or dark conditions. Cotyledons regenerated floral parts from their abaxial surfaces when cultured on (1) DKW or MS, both supplemented with (in mg/liter) 600 glutamine, 300 glycine, 200 asparagine, 50 arginine, 20 ascorbic acid and 0.05-0.1 2,4-D plus 0.1 BA or 0.1 zeatin under light or dark conditions or (2) DKW medium supplemented with (in g/liter) 2.5 Zn(NO3)2, 0.48 H3BO3, 100 KNO3 and (in mg/liter) 0.002 thidiazuron plus 0.2 2,4-D under light conditions.
Synthetic seed coats were applied to asexual embryos of carrot (Daucus carota L.) by mixing equal volumes of embryo suspension and a 5% (w/v) solution of polyethylene oxide (Polyox WSR-N 750) and dispensing 0.2 ml drops of this mixture onto teflon sheets. Drops dried to form detachable wafers consisting of embryo suspension embedded in Polyox. Embryo survival after drying was determined by redissolving wafers in embryogenic medium and culturing the rehydrated embryo suspension on filter paper supports in petri dishes for 2-3 weeks. When dried to constant weight (6.5 hr) 3% of asexual embryos coated with 2.5% Polyox survived encapsulation, whereas survival of uncoated embryos was nil. Pretreating the embryogenic suspension with 10−6 m abscisic acid (ABA) during the 14 day embryo induction phase increased coated embryo survival to 40% of the initial number of embryos.