In recent years, there has been an explosion in the number of commercial plant tissue culture (TC) units in India. More than 25 such companies have production capacity of two to five million plants per annum. Almost all units are export oriented, but the target crops are the same. Indoor foliage plants dominate the export market. Micropropagation industry in India is providing major support to Indian agriculture in four crop groups: Fruits, ornamentals, spices, forestry/plantation crops. Banana is the largest selling TC fruit crop. TC papaya plants are now marketed for extraction and processing of papain. TC anthuriums, orchids, and gerberas have attained commercial importance. TC rose plants are used as pot plants. Nearly 500 ha are under TC cardamom cultivation in southern India recording 20% to 30% increase in yield. Vanilla cultivation is expected to increase from the existing 50 ha to more than 400 ha in the coming years using TC plants. Sugar companies have in-house units for micropropagation of sugarcane. There is demand for bamboo and eucalyptus for selective reforestation. The TC Industry is constrained by the non-availability of international varieties, high infrastructure and electricity costs, and lack of managers with commercial experience. A shake-up is imperative, during which many of the existing TC units may not survive the year 2000.
Randall P. Niedz
Controlling bacterial and fungal contamination in plant tissue cultures is a serious problem. Antibiotics are currently used but are not always effective, can alter plant growth, and are costly, and resistant strains can result with extensive use. Plant preservative mixture (PPM) contains a mixture of two isothiazolones—methylchloroisothiazolinone and methylisothiazolinone, which are a class of broad-spectrum, widely used industrial biocides. The isothiazolones used in PPM are reported by the manufacturer to be nonphytotoxic at concentrations suitable for the prophylactic control of microbial contaminants in plant tissue cultures. Our results indicate that PPM can be routinely added to tissue culture medium to control air- and waterborne bacterial and fungal contaminants effectively.
R. Daniel Lineberger
The World Wide Web is the most rapidly growing communication tool in use today. The Web links networked computers of all sizes and types through use of a hypermedia application known as a “browser.” Hypermedia technology allows research-based information related to plant tissue culture to be disseminated world-wide rapidly and cheaply, and to audiences that previously had difficulty accessing the information through scholarly journals (practitioners, secondary school students, consumers). The Plant Tissue Culture Information Exchange resides on the Aggie Horticulture homepage (http://aggie-horticulture.tamu.edu). Present contents include information on suppliers of tissue culture equipment and media, research reports on micropropagation of several ornamental species, and links to tissue culture related material at other universities. Hardware, software, and network requirements to access the Information Exchange and the construction of hypertext documents for inclusion in the Information Exchange will be presented.
Y. Omura, Y. Kitaya, and T. Kozai
Air currents, and consequent diffusion processes, in the plant tissue culture vessel are slow and limit photosynthesis, transpiration, and uptake of water and nutrients by in vitro plantlets. Air currents in Magenta-type and Mayonnaise bottle-type culture vessels were visualized using fine particles of feathery crystal of metaldehyde [(CH3CHO)4] as tracers. Pictures of visualized air currents were recorded by the video camera. Air current speeds in the culture vessel were determined by analyzing the changes in video pictures with time. Air current speed around the culture vessel was set at 0.1 and 1.0 m–s–1. Shortwave radiation flux density on the shelf was varied between 0 and 34 W–m–2. Shortwave absorptivity of the medium was 44% for agar medium and 97% for agar medium containing activated charcoal. Under a shortwave radiation flux density of 10–34 W–m–2, the upward air currents were observed at the central part of the culture vessel and downward air currents were observed near the inside walls of the culture vessel. The upward air current speed was affected by air current speed around the culture vessel, shortwave radiation flux density, and shortwave absorptivity of the medium. Under shortwave radiation flux density of 34 W–m–2, the upward air current speed in the culture vessel was ≈4 times greater with 1.0 m–s–1 air current speed around the culture vessel than with 0.1 m–s–1.
Brent Tisserat and Robert Silman
A comparative study was undertaken to determine the influence of lighting, carbohydrate concentrations and ultra-high levels of CO2, i.e., >10,000 ppm, on sterile culture growth. Past CO2-sterile studies have confirmed that elevation of CO2 to as high as 1000 ppm resulted in beneficial growth. Within special constructed chambers, tissue cultures were given a variety of CO2 levels for 12–16 hours/day using artificial lighting and natural sunlight. Several different plants (lettuce, beans, pine) and plant culture types were grown in CO2-enriched environments, ranging from 350 to 50,000 ppm. In almost all cases, plant tissue cultures not only tolerated but exhibited enhanced growth using ultra-high levels of CO2. For example, lettuce cultures were found to grow 2 to 4 times faster under ultra-high CO2. levels than under normal atmospheric CO2 levels, i.e., 350 ppm. Natural sunlight was found to be suitable for sterile culture growth. Modes of administration of CO2 in vitro and gas permeability of various culture vessels are presented.
Brent Tisserat, Danny Jones, and Paul D. Galletta
Nutrient medium can be sterilized using a household-type microwave oven. The required microwave treatment time was influenced by the oven's microwave power intensity (70 to 700 W), vessel type, volume of medium employed, and the presence of energy sink water reservoirs (ESWR). Growth rates of strawberry (Fragaria vesca L.) shootlets, lemon [Citrus limon (L.) Burm. f.] fruit halves, or carrot (Daucus carota L.) callus cultured on either microwaved or autoclaved media were similar. Microwaving and autoclaving appeared to reduce GA3 activity compared with medium containing filter sterilized GA3. Chemical name used: gibberellic acid (GA3).
April S. Herring and R. Daniel Lineberger
The Univ. of Minnesota hosts the PLANT-TC Listserv as a service to the international tissue culture community (http://www.agro.agri.umn.edu/plant-tc/listserv/). One of the most frequently sought types of information is a recommendation for a “beginning point” for culturing a wide variety of plant species. Many of these inquiries come from individuals without ready access to extensive library holdings, including those in industry, public schools, and international sites. A Web site prototype that includes a searchable database of tissue culture recipes is being constructed and offered for user input. The database currently is located at http://webtutor.tamu.edu/students/herring/project/, but will be redirected to its own URL if user feedback is positive. The database also includes information about equipment and materials, media suppliers and domestic and foreign sources for tissue cultures and micropropagated plants. Other educational resources, including a virtual tour of a commercial tissue culture lab, are available on the site. The Web site and database will be reviewed by a panel of experts and modified according to their input prior to being posted for public access.
held at the 90th Annual Meeting Nashville, Tennessee 26 July 1993
Kenneth W. Mudge and Chin-Chang Chu
In vitro asymbiotic seed germination, subculture, and outplanting of orchids is presented as a laboratory exercise suitable for students of plant propagation or tissue culture. Dendrobium antennatum (Lindley), Phalaenopsis (Blume) white hybrid, or both, are used in this exercise because they flower predictably in the greenhouse, are reliable for seed production, and germinate and grow rapidly in vitro. The exercises can be used to instruct students in the skills involved in orchid seed sterilization, sowing, and culture, as well as instruct students in the unique features of orchid reproductive biology and symbiosis. A schedule is suggested for stock plant flower pollination, capsule harvest, seed sowing, and seedling subculture so that the necessary plant material is available for students to sow, subculture, and outplant seedlings during a single laboratory session.