A156 Mierograffing between N-fixing and non-N-fixing genera of the rosaceae N . E. K Y L E l, J. L. J A K O B E K 3, R. A . B A C K H A U S 2, J. C. S T U T Z 2, A N D T. L. R I G H E T T P l Department of Horticulture, Oregon State University, Corvallis, OR 97331-2911; 2Division of Agriculture, Arizona State University, Tempe, A Z 85287; and 3 Botany Department, North Carolina State University, Raleigh, NC 27695, USA BOT. GAZ. 147(3):243 246, 1986 Abstract. Successful grafts between Fallugia paradoxa and Cowania mexicana were prepared using

shoots proliferated in vitro and rootstocks of aseptically germinated seedlings. Microscopic examination through the graft union revealed vascular connections between the scion and rootstock. The Actinomycete, Frankia sp., can fix nitrogen in symbiosis with roots of C. mexicana but not with F. paradoxa. Successful grafts between the rootstock of an N-fixing genus and the scion of a non-Nfixing genus may be useful in studying the process of N fixation in nonlegume actinorhizal plants and may also have potential commercial applications for certain rosaceous crops.

Totipotence du p6ricycle des organes souterrains et a6riens de Rorippa syivestris. L Rhizogenbse et caulogenbse ~ partir de racines sur plante intacte ou de fragments de racines cultivks in vitro MAURIE-LAURE PROJETTI & DOMINIQUE CHRIQUI Universitk Pierre et Marie Curie, Laboratorire de cytologie exp&imentale et morphogenbse v~g&ale, Bftiment N2, 4, place Jussieu, F-75230 Paris CEDEX 05, France Can. J. Bot. 64:1760-1769, 1986 Abstract. Old and tuberized roots of Rorippa sylvestris (Brassicaceae) can form adventitious buds.

Moreover, in vitro culture on Murashige and Skoog medium supplemented with sucrose can induce bud regeneration from nontuberized young root explants. An unusual stimulation of both lateral rhizogenesis and caulogenesis is obtained in the presence of auxin (indoleacetic acid), with optimal responses at 5mg.L ~. Kinetin inhibits rhizogenesis but strongly enhances caulogenesis, with optimal responses between 1 and 5mg.L l In all conditions (natural and experimental), lateral roots and buds arise from the pericycle layer or pericycle-derived tissues (outer layer of a severallayered pericycle, phellogen, and pericycle-derived callus). Thus, the pericycle of R. sylvestris roots, as well as the pericycle-derived cells, exhibits an original double potential for rhizogenesis and caulogenesis, especially in the close vicinity of the xylem poles. As the early steps of root and bud regeneration are similar, the possibility that the two:,kinds of meristems are undetermined and perhaps interchangeable is considered.

A157

Totipotence du p~ricycle des organes souterrains et a~riens de

Rorippa sylvestris. II. R~g~n&ation de racines et de bourgeons h partir de feuilles d~tach~es ou de fragmentsfoliaires cultiv~s in vitro MARIE-LAURE PROJETTI & DOMINIQUE CHRIQUI UniversitO Pierre et Marie Curie, Laboratoire de cytologie expkrimentale et morphogenbse vOgktale, B6timent N2, 4, place Jussieu, F-75230 Paris CEDEX 05, France

Can. J. Bot. 64:1770-1777, 1986 Abstract. When detatched and placed on water, leaves of Rorippa sylvestr& (Brassicaceae) can rapidly initiate roots and subsequently buds at their proximal end. This ability can be modulated through in vitro culture of leaf explants with exogenous growth hormones. Indoleacetic acid enhances both rhizogenesis and caulogenesis with optimal responses at 10mg.L t. Kinetin inhibits the two processes when applied at low concentration (0.05 mg.L t) and leads to necrosis above 0.1 mg.L ~. When applied simultaneously or as a short pretreatment (48 h), indoleacetic acid cancels the toxic effects of kinetin and increases budding. Budding always occurs after rhizogenesis. In all the experiments, roots and buds arise from reactivation of cells belonging to the pericycle surrounding the vascular bundle and located near the protoxylem vessels. Sequential treatments applied in order to induce early morphogenetic reorientations in this totipotent layer are also presented. The double organogenetic ability of the pericycle is discussed as well as the absence of interconversion between root and shoot meristems.

l~tude pr~liminaire sur l'organogen~se adventive ~ partir d'embryons de tulipe cultiv~s in vitro (Tulipa gesneriana) B. AUBERT j, G. WEBER l, N. DORIO I, M. LE NARD 2 & C. BIGOT j 1Chaire de physiologie vOgktale appliquOe, tEcole nationale supOrieure d'horticulture, 4, rue Hard),, F-78009 Versailles CEDEX," 2Station d'am~lioration de la pomrne de terre et des plantes h bulbes, lnstitut national de la recherche agronomique, B.P. 5, F-29207 Landerneau CEDEX, France

Can. J. Bot. 64:1837 1842, 1986 Abstract. In vitro tulip embryos have an active shoot-forming capacity (up to 320 neoformations

per embryo, for a 20-month period) when cultured, at a temperature of 20-24 ~C under a 16-h day length (4000Ix), with growth regulators: naphthalene-acetic acid (0.5mg.L -~) and benzylaminopurine (I mg.L -t) or kinetin (0.5mg.L - t ) or isopentenyladenine (1 mg.L t). Repeated fragmentations improve or maintain shoot-forming ability. Nevertheless, an important genotypic effect is observed. When neoformations are subjected to a cold treatment of at least 40 days at 6 °C under short days (8 h, 2500 Ix) and then transferred at 24 °C under long days (16 h, 800 Ix), they produce numerous functional bulblets.

A158 In vitro control of caulogenesis by growth regulators and media components in embryonic explants of eastern white pine (Pinus

strobus) BARRY S. FINN, DAVID T. WEBW & WANDA GEORGIS Department of Biology, Queen's University, Kingston, Ont., Canada K7L 3N6; l Present address. Agrogen Biotechnologies lnc., Agrogen Building, 520 West 6th Avenue, Vancouver, B.C., Canada V5Z 4H5 Can. J. Bot. 64:1948-1956 Abstract. Horizontally oriented embryos of Pinus strobus (L.) produced shoots on Schenk and Hildebrandt medium containing cytokinin. Shoots developed primarily from cotyledons in contact with the medium. Seed pretreatments at 5 or 27 °C did not affect caulogenesis. N~-Benzyladenine (BA) and Nr-(A2-isopentenyl)adenine (2iP) both induced caulogenesis, with BA being 10-20 times more potent than 2iP. High BA levels caused callus formation. BA exposures from 1 to 8 weeks were equally caulogenic with horizontal explants, but exposures longer than 2 weeks led to increased variability and callus formation. A l-week, upside-down, vertical orientation during BA treatment increased the uniformity of cotyledon response and was as caulogenic as a 4-week horizontal BA exposure. Neither auxins nor triiodobenzoic acid induced or significantly enhanced shoot formation. Full-strength Schenk and Hildebrandt medium was superior to Murashige and Skoog medium for shoot induction. Dilution of Schenk and Hildebrandt medium had no significant effect on shoot production, but shoot elongation was suppressed on one quarter strength Schenk and Hildebrandt medium. Half-strength Murashige and Skoog medium was as caulogenic as Schenk and Hildebrandt medium. The NH 4 level of the macronutrients was responsible for the difference between Schenk and Hildebrandt medium and Murashige and Skoog medium. The higher NH 4 concentration of Murashige and Skoog medium inhibited shoot formation.

Cell determination during embryogenesis in Citrus jambh&i.

IlL Graft formation and nonformation in embryonic tissues DAVID K. BRUCK & DAN. B. WALKER Center for the Study of Evolution and the Origin of Life, Geology Building, University of California, Los Angeles, CA 90024, USA Can. J. Bot. 64:2057-2062. Abstract. Approach grafts were constructed using embryos in vitro with and without surface tissue removal along the root--hypocotyl axis. All embryonic stages from mid-heart through mature proved competent to graft after surface excision. Early heart-shaped embryos grafted back to themselves when a longitudinal incision was made which cut the hypocotyl in half but left the root intact. Cut globular embryos could not be maintained in position for a sufficient period to generate a graft union. Callus tissue was produced in all cut embryos by internal cells but not by surface cells neighboring the cut region. Intact embryos failed to graft or respond in any fashion. The incompetence to graft of surface tissues at all embryonic stages indicates that those tissues are determined as epidermal even in the earliest stages of embryogenesis. Internal cells of the embryo were not epidermal in response. They were able to form callus and graft with increasing ease toward older stages of embryogenesis.

A159

An ultrastructural study of embryo and endosperm development during in vitro culture of maize ovaries (Zea mays) J. H . N . S C H E L

& H. KIEFT

Department of Plant Cytology and Morphology, Agricultural University, Arboretumlaan 4, 6703 BD Wageningen, the Netherlands Can. J. Bot. 64:2227 2238 Abstract. A culture method is described which allows the continuous supply of fresh liquid medium and which prevents the accumlation of toxic metabolites. Development of maize embryos and endosperm after various periods of in vitro ovary culture was studied by light and electron microscopy. Using this method the ultrastructural features of embryo development in vitro were similar to those of in vivo embryos. In contrast, the formation of endosperm was irregular with the absence of cellularization of the inner endosperm being frequent. In some cases, only the endosperm developed without any indication of embryo formation. In a calcium-depleted medium, embryo development was normal but again, endosperm formation was aberrant. No cells were formed in the central part of the endosperm and near the placental region degeneration took place, resulting in vacuoles with dark inclusions, clumps of rough endoplasmic reticulum membranes, and cellular breakdown. The events occurring after in vitro culture strongly resemble those taking place after intergeneric crosses or crosses between diploid and tetraploid strains. It is concluded that defective endosperm development is probably the main factor for the failure of embryo development.

Growth and morphogenesis in short-term nodal cultures of an apple rootstock in vitro G. S. HICKS & A. NAIR Department of Biology, Dalhousie University, Halifax, N.S., Canada B3H 4J1 Can. J. Bot. 64:2299-2304 Abstract. Nodal cultures of a cold-hardy apple rootstock were inoculated and grown for 18 days on

Murashige-Skoog medium supplemented with benzylaminopurine (BAP). The axillary buds (primary buds) require benzylaminopurine at 0.1 or 1.0 mg L-~ for optimal development as measured by the increase of fresh and dry weights, frequency of buds with expanded leaves, and development of new (secondary) buds from microscopic axillaries on the primary bud. Growth of the original axillary bud was reduced in the absence of the single subtending leaf, but there was no reduction in bud growth when BAP was supplied during the first 3 days. However, secondary bud growth required both the continuous supply of 1.0 mg L ~ BAP and the presence of the subtending leaf.

A160 Production de plantes haplo'ides de Gerbera jamesonii par culture in vitro d'ovules MAMAR AHMIM ET JOACHIM VIETH Institut botanique, UniversitO de MontrOal, 4101, rue Sherbrooke est, MontrOal (Qua.), Canada H I X 2B2 Can. J. Bot. 64:2355-2357 Abstract. Unfertilized ovules of Gerberajamesonii were cultivated in vitro and haploid plants were successfully regenerated. Five concentrations of sugar, and four hormonal combinations containing indole acetic acid and benzyl adenine were tested. The best results were obtained with 0. I mg indole acetic acid/L and 0.2mg benzyl adenine/L; 1% sugar in the medium was sufficient for callus production and regeneration of plantlets from the clone of the experimental cultivar, 'Super Gerbera'. One hundred and fifty ovules per capitulum can be cultivated and under optimal conditions a frequency of 5% haploid plantlets can be obtained.

Temperature and photoperiod responses of soybean embryos cultured in vitro C. DAVID RAPER Jr. & ROBERT P. PATTERSON Departments of Soil Science and Crop Science, North Carolina State University, Raleigh, NC 27695-7619, USA Can. J. Bot. 64:2411-2413 Abstract. Temperature and photoperiod each have direct effects on growth rate of excised embryos of soybean (Glycine max (L.) Merrill). To determine if the effects of photoperiod are altered by temperature, embryos of'Ransom II' were cultured in vitro at 18, 24, and 30 °C under photoperiod durations of 12 and 18 h at an irradiance of 9 W m -2 (700 to 850 nm) and a photosynthetic photon flux density of 58/lmol m 2s- ~(400 to 700 nm). Accumulation rates of fresh and dry weight were greater under 18-h than 12-h photoperiods over the entire range of temperature. Water content of the cultured embryos was not affected by photoperiod but was greater at 18 and 30 than 24 °C. The accumulation rate of dry weight increased from 18 to 26 but declined at 30 °C.

A161 Influence de la teneur en gaz carbonique sur la morphogen~se de la vigne en culture in vitro JEAN-CLAUDE F O U R N I O U X & R O G E R BESSIS Laboratoire des sciences de la vigne, FacultO des sciences, B.P. 138, F-21004 Dijon CEDEX, France Can. J. Bot. 64:2608 2616

Abstract. Two different types of morphogenesis are induced in vitro in the grapevine by changing the system of sealing the culture tubes (with or without Parafilm). The differences appear mainly in the degree of miniaturiation: the plants the most miniaturized, those with Parafilm, have all the characteristics of an immature juvenile state. The others, without Parafilm, show an intermediate morphology between the adult and the juvenile forms. It follows then that the importance of juvenile characters is linked to the degree of miniaturization. One of the effects of Parafilm is in the modification of the amount of CO2 in the atmosphere of the tubes: in excess during the dark phase and in severe shortage during the light phase. We have found then, that among all the environmental factors which could influence the morphogenesis of the grapevine in vitro, CO 2 appears to play a relatively important role.

Abscisic acid and low temperature induced polypeptide changes in alfalfa (Medicago sativa) cell suspension cultures ALBERT J. ROBERTSON & LAWRENCE V. GUSTA Crop Development Centre, University of Saskatchewan, Saskatoon, Sask. Canada S7N OWO Can. J. Bot. 64:2758 2763.

Abstract. Changes in extracellular, cellular, and subcellular proteins during abscisic acid and low temperature induced cold hardening of alfalfa (Medicago sativa L. cv. Wisconsin 22C) cell suspension cultures were investigated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Extracellular proteins from 4- to 6-day-old ABA and low temperature grown alfalfa cells showed decreased electrophoretic mobilities, lacked a 190-kDa glycoprotein, and had reduced amounts of four other polypeptides. In total cell protein analyses, a 42-kDa protein was enriched in both ABA and low temperature treated alfalfa cells. Several proteins increased or induced by exogenous ABA treatment were identified in the extracellular (12.5 and 13 to 15kDa), total cell and cell wall (24kDa), and soluble (20, 37, and 41 kDa) fractions. However, no major protein changes were resolved by one-dimensional electrophoretic analyses of crude membrane proteins.

A162

Crocus sativus pollen germination and pollen tube growth in vitro and after intraspecific and interspecific pollination G. CHICHIRICCO l & M. GRILLI CAIOLA 2 ZDipartimento di Scienze Ambientali, University of L'Aquila, Italy; 2Dipartimento di Biologia, H University of Rome, via O. Raimondo, 1-00173 Roma, Italy Can. J. Bot. 64:2774-2777. Abstract. The germination and tube growth of saffron (Crocus sativus L.) pollen were studied in vitro

(in liquid media) and in vivo in pistils of Crocus sativus and Crocus thomasii after intraspecific and interspecific pollinations. In vitro about 20% of the saffron pollen grains germinated, but only about 9% developed a pollen tube. Although 21% of the pollen germinated on the stigmas, most pollen tubes ceased growth in the pistil and only a low percentage (about 6% of germinated grains) reached the ovary, where few of the ovules (about 5%) were penetrated. The defective germination and pollen tube growth were correlated with the occurrence of cytological abnormalities of the saffron pollen. Moreover, the ovarian transmitting tissue appeared to prevent the penetration of the ovules.

Interaction of Agrobacterium tumefaciens with soybean (Glycine max (L.) Merr.) leaf explants in tissue culture D. T. KUDIRKA j, S. M. COLBURN, M. A. HINCHEE, & M. S. WRIGHT Cellular and Molecular Biology, Plant Sciences Division, Monsanto Agricultural Products Company, 700 Chesterfield Village Parkway, St. Louis, MO 63198, USA; ~Present address: Department of Plant Sciences, University of Western Ontario, London, Ont. Canada N6A 5B7 Can. J. Genet. Cytol. 28:808-817 Abstract. Wounded petiole surfaces of excised soybean (Glycine max (L.) Merr.) leaves of 'Peking'

formed neoplastic growths testing positive for opines after inoculation with a tumorigenic strain of Agrobacterium tumefaciens. During the 48-h inoculation period, uninoculated explants and explants inoculated with A136 (avirulent), A208 (tumorigenic), and ASE1-200 (nontumorigenic) strains of A. tumefaciens showed initiation of mitotic activity at the wound surface conforming with classical descriptions of the wound response; however, shortly after explant transfer to tissue culture medium, morphogenetic patterns in explants inoculated with tumorigenic A. tumefaciens deviated from the uninoculated and A 136 inoculated controls. This developmental deviation was correlated to the presence of the Ti plasmic in the bacterium. Explants inoculated with nontumorigenic A. tumefaciens showed a morphogenetic pattern intermediate between the controls and explants inoculated with tumorigenic bacteria. This suggests that the latter plant response might be due to a plant regulator gene found in the vir region of the Ti plasmid. Explants inoculated with tumorigenic bacteria showed decreasing efficiency of transformation if inoculations were delayed 4h after excision and explants showed greatest thermosensitivity to transformation during the 48-h inoculation period. Reduced thermosensitivity was evident after transfer to tissue culture medium supplemented with carbenicillin. In this in vitro inoculation procedure, 'Peking' was shown to be twice as transformable as 'Corsoy 79'. This offers an opportunity to determine if there is a heritable component associated with transformation in this soybean explant system.

A163 Somatic polyembryogenesis from callus of mature sugar pine embryos P R A M O D K . G U P T A & D O N J. D U R Z A N Department of Pomology, University of California, Davis CA 95616, USA Bio/Technology Vol 4, July 1986 Abstract. An embryogenic callus was isolated from suspensor cells of 5-year-old sugar pine seeds.

With a newly formulated basal medium and by removal of 2,4-D followed by in addition of BAP, globular somatic embryos were induced having elongated suspensors. In darkness, embryos elongated and formed numerous cotyledons in a repetitive and true-to-type polyembryonic process. When separated from one another, none of the embryos showed overt evidence of lethal or competitive effects under in vitro conditions.

Gene transfer into loblolly pine by Agrobacterium tumefaciens R O N A L D S E D E R O F F I, A N N E - M A R I E S T O M P 2, W . S C O T T C H I L T O N 3, & L A R R Y W. M O O R E 4 ~Institute of Forest Genetics and the Pacific Southwest Forest and Range Experiment Station, USDA Forest Service, P.O. Box 245, Berkeley, CA 94701, 2Department of Forestry, and 3Department of Botany, North Carolina State University, Raleigh, NC 27695, 4Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA Bio/Technology Vol. 4, July 1986 Abstract. We have demonstrated expression of bacterial genes transferred into cells of loblolly pine

( Pinus taeda L.) by Agrobacterium tumefaciens. Whereas previous surveys found pines resistant to Agrobacterium, we found two wild type strains that produce galls. Callus proliferated from these galls synthesized specific opines. These results provide strong evidence for transfer and expression of bacterial genes in pine and extend the potential of genetic engineering to the world's most important genus for fiber production.

A164 Somatic seeds: encapsulation of asexual plant embryos KEITH REDENBAUGH, B R I A N D . P A A S C H l, J A M E S W. N I C H O L 2, M A R Y E. K O S S L E R , P E T E R R. V I S S & K E I T H A. W A L K E R Plant Genetics, Inc., 1930 Fifth Street, Davis, CA 95616; ~Present address: BioRad Chemical Division, 1414 Harbour Way South, Richmond, CA," 21GB Products. Ltd., 14310 Catalina St., San Leandro, CA 94577, USA Bio/Technology Vol. 4, September 1986 Abstract. Somatic embryos (SE) of alfalfa, celery, and cauliflower were encapsulated as single-

embryo beads approximately four millimeters in diameter to produce individual somatic (artificial) seeds. The SE were mixed in sodium alginate and dropped into a solution of calcium chloride to form calcium alginate beads via an ion exchange reaction. For our two best somatic embryogenesis systems, alfalfa and celery, in vitro germination frequencies with production of seedling-quality plants were routinely 30% and 65%, respectively. In addition, encapsulated alfalfa and celery SE developed into plants in sand trays or in transplant plugs at frequencies of 7% and 10%. The production of seedling-quality plants from individual somatic seeds, as first reported here, has potential as a novel, universal delivery system.

Efficient transformation of alfalfa protoplasts by the intranuclear microinjection of Ti plasmids T.J. R E I C H 1, V. N . I Y E R 1, & B. L. M I K I 2 t Department of Biology, Carleton University, Ottawa, Ontario K I S 5B6 and 2Genetic Engineering Section, Plant Research Centre, Agriculture Canada, Ottawa, Ontario KIA 0C6, Canada Bio/Technology Vol. 4, November 1986 Abstract. Intranuclear microinjection of alfalfa (Medicago sativa L.) protoplasts yielded transforma-

tion frequences of 15-26%. Over 70 transformed callus lines were recovered without selection by microinjecting a variety of plasmids. Analyses of several lines transformed with pTiC58 showed that integration did not occur by the T-DNA mechanism typical for crown gall tissues. The presence of a functional T-DNA right border on smaller plasmids or the coinjection of a functional vir region on a separate plasmid did not increase the transformation frequencies. The novelty of this approach to the genetic transformation of plants is that selection systems are not required and restrictions on the host range of Agrobacterium tumefaciens may be circumvented.

A165

Co-transformation of unlinked foreign genes into plants by direct gene transfer R . J. S C H O C H E R , R . D . S H I L L I T O 1, M . W . S A U L , J. P A S Z K O W S K I & I. P O T R Y K U S Friedrich Miescher-lnstitut, P.O. Box 2543, CH-4002 Basel, Switzerland," 1Present address." Ciba Geigy Corp., P.O. Box 12257, Research Triangle Park, Raleigh, NC 27709-2257, USA Bio/Technology Vol. 4, December 1986 Abstract. Direct gene transfer experiments were carried out to find the rate of co-transformation of

non-selectable and selectable (kanamycin resistance) genes offered to tobacco protoplasts as naked DNA on separate plasmids. After co-transformation, we could detect the presence of sequences from a zein genomic clone in up to 88% of kanamycin, resistant (pABDI containing) cell clones, and a fragment containing the full zein genomic clone was found in up to 33% of the latter cases. In co-transformations with a nopaline synthase gene, up to 47% of the kanamycin resistant clones obtained in one treatment contained the non-selected gene, and the gene was complete and active in all of these latter cases. The high efficiency of co-transformation shows that direct gene transfer provides a rapid and easy method of introduction of non-selectable genes into plant genomes.

Efficient plant regeneration from rice protoplasts through somatic embryogenesis RUSLAN ABDULLAH, EDWARD C. C O C K I N G & JOHN A. THOMPSON Plant Genetic Manipulation Group, Department of Botany, University of Nottingham, Nottingham, U.K. Bio/Technology Vol. 4, December 1986 Abstract. Progress in the genetic manipulation of cereals using protoplast technology has been limited by a lack of reproducible plant regeneration from protoplasts of these important species. Here we report that plant regeneration can be achieved efficiently and reproducibly from protoplasts of rice isolated from cell suspension cultures. Regeneration from 10-20% of protoplast-derived colonies of two varieties was obtained rapidly after direct transfer to a hormone-free medium. Green plants were produced at a high frequency through somatic embryogenesis. The protoplast origin of the regenerated plants is unequivocally demonstrated by the inability of contaminating intact cells to divide.

A166 Trends in the use of tissue culture in forest improvement Review

B R U C E E. H A I S S I G , N E I L D. N E L S O N j, & G E O R G E H. K I D D 2 USDA-Forest Service, North Central Forest Experiment Station, Forestry Sciences Laboratory, P.O. Box 898, Rhinelander, WI 54501 (corresponding author.) 1Present address: Forgene Inc., 7014 Fire Tower Rd., Rhinelander, WI 54501; 2 L. William Teweles & Co., 777 E. Wisconsin Ave., Milwaukee, WI 53202, USA Bio/Technology Vol. 5, January 1987 Abstract. We have analyzed and described the problems and potentials of using tissue culture in

micropropagation and biotechnologies related to forest improvement. Trends in forest management concepts, commercial micropropagation, and tissue culture biotechnologies are discussed. Our analysis suggests that tissue culture will contribute significantly to the improvement of forests through exploitation of existing genotypes and production of new, commercially valuable genotypes. Such changes may significantly influence worldwide management decisions in forestry.

Biotechnology of somatic polyembryogenesis and plantlet regeneration in loblolly pine PRAYMOD

K. GUPTA & DON J. DURZAN

Department of Pomology, University of California, Davis, CA 95616, USA

Bio/Technology Vol. 5, February 1987 Abstract. Plantlets of loblolly pine were regenerated and converted to soil by somatic polyem-

bryogenesis (SPE). SPE was evoked in cells from an embryonal-suspensor mass whose nuclei were color-coded by a double-staining method. Color-coding with cell suspension cultures distinguished a free-nuclear stage, initial physiological states and the ultimate fate of each cell for estimates of yield based on the initial properties of embryogenic and nonembryogenic cell masses. Somatic embryos were encapsulated and stored in an alginate gel or in liquid nitrogen.

A167

Adventitious shoots from cotyledons of immature cherry and apricot embryos W. DAVID LANE 1 & F.

COSSIO 2 Research Station, Agriculture Canada, Summerland, British Columbia VOH 1ZO; and 21nstituto Sperimentale de Frutticoltura, 37135 Verona, Via S. Giacomo, 25 Italy Can. J. Plant Sci. 66:953-959, 1986 Abstract. Immature embryos of Prunus armeniaca (apricot) and Prunus persica (peach) collected

20-30 d from anthesis were cultured on Murashige and Skoog medium supplemented with benzyladenine (BA) and various auxins to study their potential for regeneration. Both species developed adventitious buds on cotyledons when cultured in vitro. Apricot frequency of regeneration was as high as 100% when BA (5.0 pM) and 2,4-D (1.0/~M) were included in the medium. Cherry response was less than apricot (up to 70%) and the maximum frequency of regeneration occurred using media with BA alone (3.0 pM). Auxin was inhibitory to sweet cherry regeneration. The physiological stage of development was very important for regeneration from both species since regeneration did not occur when very young or fully mature embryos were used as explants. Apricot plants were produced by rooting shoots which developed from the regenerated buds on the cotyledons.