Henry R. Owen

Culture medium pH is influenced by basal medium, carbohydrate source, gelling agent, activated charcoal, and medium storage method

SummaryWhen four carbohydrates were tested against six commonly cited inorganic basal media, post-autoclave pH was highest for carbohydrate-free and sucrose containing media, and progressively lower for maltoseglucose and fructose-containing media, respectively. Post-autoclave pH for these media without carbohydrates was related to medium buffering capacity. Addition of gelling agents (10 of 11 tested) increased the postautoclave pH of MS medium containing sucrose. Neutralized and acid-washed activated charcoal also increased the post-autoclave pH of liquid and agarsolidified MS medium, and the pH changed further during 8 weeks of storage. Changes in medium pH caused by gelling agents, but not charcoal, could be alleviated by adjusting the pH after their addition but prior to autoclaving.

Haploid plant regeneration from anther cultures of three north american cultivars of strawberry (Fragaria x ananassa Duch.)

SummaryA study was conducted to maximize plant regeneration frequencies from cultured anthers of ‘Chandler’, ‘Honeoye’, and ‘Redchief’ strawberries (Fragaria x ananassa Duch.). A comparison of auxins (IAA, NAA), cytokinins (BA, BPA, KIN) and carbohydrates (sucrose, glucose, maltose) in MS medium showed that the highest shoot regeneration across cultivars (8%) occurred when using a medium containing 2 mg/l IAA, 1 mg/l BA, and 0.2 M glucose. A comparison of MS, NN, and H1 inorganic medium (a new formulation based on the anther culture literature) solidified with either agar or gellan gum and containing IAA, BA, and glucose, showed the highest shoot regeneration across cultivars (19%) when using H1 and gellan gum. Lastly, media containing Fe-EDTA yielded more shoots than media containing Fe-Metalosate, and anthers cultured on Fe-EDTA media in darkness for 30d followed by 30d in white light produced more shoots (16% average regeneration) than those cultured on Fe-EDTA media under white or yellow light (16h photoperiod) for the initial 30d (0.3% and 5% respectively). Plants were acclimated ex vitro where they flowered and set fruit. Chromosome counts of root tip cells confirmed that haploid plants were obtained from all three cultivars.

An examination and correction of plant tissue culture basal medium formulations

The inorganic formulations of fourteen common plant tissue culture basal media were examined from the primary literature. Inaccuracies and errors were found for molecular formulae, chemical hydrations, and molar equivalences for iron/EDTA complexation. A comparison with published basal medium formulations from six commercial suppliers uncovered additional inaccuracies, modifications, and errors, thereby emphasizing the need for investigators to examine and describe medium formulations precisely in future publications.

Floral Biology of Physaria ludoviciana (Brassicaceae), a Plant Rare to the Midwest

ABSTRACT Physaria ludoviciana (Brassicaceae) is rare in Illinois, Minnesota, and Wisconsin. Environmental effects on floral development are unclear. Both self-compatibility and self-incompatibility occur within Physaria species. Objectives were to describe flowers, to determine how photoperiod affects flower development, and to predict whether flowers are self-compatible or self-incompatible. For photoperiods, greenhouse-grown plants were placed in either 16 or 8 hr photoperiods. Inflorescences and open flowers were counted weekly. For pollination, flowers were self-pollinated or cross-pollinated. Plants developed inflorescences after 20 and 28 d in long and short days, respectively. Inflorescences/plant increased for both photoperiods throughout the study. In short days, plants produced more inflorescences (10.8/plant) than in long days (7.1/plant). Anthesis started at 48 and 56 d for long and short days, respectively. Blooming peaked at 83 d (4.9 flowers/plant/day) for long days, and at 98 d (3.5 flowers/plant/day) for short days. Cross-pollinated flowers produced fruits, while self-pollinated ones did not.

Scarification Technique Affects Germination of Stylisma pickeringii (Patterson bindweed), an Illinois Endangered Plant

Abstract The seed coat of Stylisma pickeringii (Torr.) Gray var. pattersoni (Patterson bindweed), an endangered species of Illinois sand prairies, inhibits water uptake and seed germination. The purpose of this research was to find an effective and efficient way to scarify seeds of S. pickeringii to aid reintroduction into its natural habitat. Seeds were collected from sandy areas close to the Illinois River near Snicarte (Mason Co.), Illinois during the summers of 1998 and 1999. Experiments were conducted to determine the best scarification techniques (basal cut, sandpaper shakes, sulfuric acid, sand shakes and sonication). Initially, each technique was evaluated by scarifying the seeds for different times (except for the basal cut). The optimal time for each scarification technique then was compared. Scarified seeds were germinated in petri dishes at 25 C, 16 h photoperiod, with a mean light intensity of 51 μ mol m−2s−1. The basal cut, 48 h sandpaper shake, 120 min acid soak and 72 h sand shake techniques did not differ significantly in germination (96, 92, 84 and 84%, respectively). The sonicator technique and the unscarified control yielded only 4 and 0% germination, respectively. For scarification of S. pickeringii seeds the 48 h sandpaper shake and 120 min acid soak were very effective and efficient relative to other techniques. Of these two techniques, the sandpaper shake is safer than the acid soak, although when scarifying large numbers of seed, the sandpaper shake would require a large shaker. The techniques have potential applicability to other threatened and endangered species whose seed coat also inhibits germination.

Influence of Reproductive and Environmental Factors on Population Size of Wild Hyacinth [Camassia angusta (Engelm. and A. Gray) Blank. (Liliaceae)], an Illinois Endangered Species

Abstract Wild hyacinth (Camassia angusta) is a perennial species native to mesic prairies of the midwestern and south-central United States. In Illinois, the only extant population of this state-endangered species is in a small section of degraded black-soil prairie along a railroad track right-of-way south of Elwin, Macon County. The objectives of this study were to determine the population status, seed production, and effects of scarification and stratification on germination of C. angusta. The population was surveyed from 1990 to 2007. A survey of other plant species present was conducted in 1999. The site consisted of approximately 75% native and 25% exotic species. The number of flowering stems of Camassia angusta fluctuated significantly (28 to 169 plants) during the course of this study. Prescribed spring burns and a construction equipment disturbance may be partially responsible for these fluctuations. A large percentage of undeveloped fruit, resulting in low seed production (<3,000), as well as low seed germination (8%), may be responsible for this populations inability to increase consistently in number of individuals.

Surveys of Stylisma pickeringii var. pattersonii (Convolvulaceae), Its Associated Plant Species, and Its Insect Visitors

Abstract Stylisma pickeringii var. pattersonii (Convolvulaceae) is endangered in Illinois and Iowa, and occurs in scattered populations in other states. During 1999 and 2000, two insect species previously unreported from Illinois were observed visiting its flowers. This study was undertaken to survey additional insect visitors, as well as to characterize the plant community where S. pickeringii occurs. The objectives were to survey: 1) floral traits (anthesis and flower density) of S. pickeringii, 2) associated plant species, and 3) insect visitor characteristics. Floral traits were determined and associated plant species surveyed in Mason County (degraded hay field on private property) and Henderson County (dry sand prairie at the Big River State Forest), Illinois. Insects visiting flowers were collected at 10:00 a.m., 12:30 p.m., and 3:00 p.m. during June, July, and August in 2001 and 2002. Individual flowers lasted one day and remained open for 6–8 hours. Peak flowering occurred from early to the middle of July when S. pickeringii was the dominant species in flower. Henderson County contained a greater diversity of native plant species with less bare ground and fewer non-native species than the Mason County site. Forty-seven insect species were observed visiting S. pickeringii flowers. Most frequent visitors were Apis mellifera (Hymenoptera: Apidae), Bombylius fraudulentus (Diptera: Bombyliidae), and Heterostylum croceum (Diptera: Bombliidae). The diversity of visiting insects was higher earlier than later in the day, in July and August than June, and in Henderson than Mason County.