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.
S. Kitto and L. Griffiths
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.
S. Adam and S.L. Kitto
Boshou Liao and S.L. Kitto
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.
S.L. Kitto and G. McGranahan
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.
Susan Foster and S.L. Kitto
Wild populations of Spigelia marilandica, a clump-forming perennial, are being destroyed because of its recent popularity and the plant is now becoming rare in its native habitat. The effect of the stock plant environment on the rooting capability of Spigelia marilandica cuttings is the primary focus of this research. Cuttings were obtained from greenhouse (GH) grown plants on a monthly basis, and from plants maintained in outside field beds (FB), season permitting. Cuttings were dipped in Hormodin 1 (1000 IBA), placed in a perlite:peat mix, and put under mist for 8 weeks. During the experiment, 91% rooting of cuttings obtained from GH-grown plants and 35% rooting of cuttings obtained from FB-maintained plants was observed. Cuttings from GH-grown plants averaging 39 roots/cutting (average FW/cutting = 1.243 g, average DW/cutting = 0.1574 g) were compared to cuttings obtained from FB-maintained plants averaging 9 roots/cutting (average FW/cutting = 0.6041 g, average DW/cutting = 0.0663 g). A statistically significant difference was found between the two stock plant environments, with the cuttings from the GH-grown plants having an advantage over the cuttings obtained from the FB-maintained plants. A separate comparison was made of the cuttings obtained from the GH-grown plants over the 12 months of the experiment and the analysis showed no significant difference in the average FW/cutting, DW/cutting, and the number of roots/cutting.
Susan Foster and S.L. Kitto
Spigelia marilandica, an herbaceous perennial native to the temperate eastern United States, has great potential for the sunny garden; however, its availability is limited due to propagation difficulties. The effect of stock plant environmnet on the rooting capability of the cuttings is the primary focus of this research. Shoot-tip cuttings were collected monthly from stock plants maintained under high-intensity sodium lamps providing a 16 hr day/8 hr night photoperiod. Cutting bases were dipped in Hormodin I (1000 IBA), placed in a perlite:peat (4:1) mix, and placed under mist for 8 weeks. Preliminary data indicates that 95.5% of the cuttings rooted with an average of 39 roots per cutting.