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The Stomata of Gnetum 总被引:1,自引:0,他引:1
In both Gnetum gnemon and G. ula the atomatal development inthe collars and axes of the male and female cones and the outertwo envelopes of the ovule is of the haplocheilic type. In theleaf some stomata do show parallel subsidiary cells, but theyarise from the surrounding epidermal cells and do not seem tohave a common origin with the guard cells. This conflicts withearlier accounts and is of interest in relation to the typesof stomata met with in other gymnosperms, living and fossil. 相似文献
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Anthers of Allium cepa and Rhoeo discolor, excised at leptotene-zygoteneand diplotene-diakinesis, have been cultured in modified White'smedium supplemented with different concentrations of ribonucleicacid and desoxyribonucleic acid. The best development was obtainedwith ribonucleric acid in which there was a 100 per cent. survivalof the microspore mother cells up to the formation of 1-celledmicrospores. In R. discolor, the time taken by the microsporemother cells to form tetrads in vitri was half of that requiredin nature. All attempts to induce division of the microsporenucleus in vitro failed. 相似文献
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Germination in vitro of pollen grains of Petunia hybrida L.is sharply reduced by brief elution with cold distilled water.If eluted substances are added back to eluted pollen germinatingin vitro, the germination capacity is significantly restored.A heat-labile protein fraction (50000100000 daltons)is responsible for restoring the germination ability. Petunia hybrida L, pollen, protein, diffusates, germination 相似文献
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Embryogenic cell suspension cultures were established from calliderived from young leaves of sugarcane (Saccharum officinarumL.) by placing them in liquid medium containing 5 per cent coconutwater (CW), 23 mg 11 2, 4-D and 500 mg 11casein hydrolysate (CH). The cultures were maintained by transferring2.55.0 ml of the suspension to 35 ml of fresh mediumevery 45 days. Organized structures resembling the earlystages of embryogeny were formed when 2, 4-D in the medium waslowered (0.11.0 mg 11) but these did not developbeyond the globular or early scutellar stages. High levels ofsucrose (610 per cent) promoted the formation of proembryoids.Plating of the suspension on MS agar medium supplemented with0.252.0 mg 11 2, 4-D, 5 per cent CW, 500 mg 11CH, with or without activated charcoal, resulted in the formationof embryogenic calli. A large number of embryoids were formedin media containing lower 2, 4-D concentrations. Transfer ofembryoids to half-strength MS medium with 6 per cent sucroseestablished plantlets which were successfully transferred tosoil. Saccharum officinarumL, sugarcane, suspension culture, embryogenesis, regeneration 相似文献
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Somatic Embryogenesis and Plant Regeneration from Suspension Cultures of Pearl Millet (Pennisetum americanum) 总被引:2,自引:0,他引:2
Immature embryos of Pennisetum americanum (pearl millet), culturedin the presence of 2,4-dichlorophenoxy acetic acid (2,4-D) produceda pale-yellow and compact callus tissue by proliferation ofthe scutellum. Teased pieces of the compact callus were placedin a liquid medium on a gyrotory shaker to establish suspensioncultures. The cultures were composed of large, elongated andhigly vacuolated cells, and a population of richly cytoplasmiccells. The latter, here termed embryogenic cells, containednumerous plastids with starch, and occurred in tight groupsof four or more cells, and occasionally as single cells. Structuresresembling various stages of embryogenic development were foundin the suspension cultures. When the cultures were plated ina 2,4-D-free agar medium containing abscisic acid, embryoidswith the typical organization of cereal embryos were produced.The embryoids germinated in vitro to give riseto plantlets, which were successfully transferred to soil. Theregenerated plants showed the normal diploid chromosome numberof 14. Embryoids apparently arose from single embryogenic cells,either directly or after the formation of a proembryonal massof cells. embryogenesis, pearl millet, Pennisetum americanum, regeneration, suspension culture 相似文献
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Embryogenic calluses derived from cultured immature embryosand young inflorescences of Panicum maximum Jacq. were placedin Murashige and Skoog's liquid medium supplemented with 1 mg11 2, 4- dichlorophenoxyacetic acid (2, 4-D) and 2.5per cent coconut water, to initiate suspension cultures. Suspensionsconsisted of two types of cells: small, richly-cytoplasmic andoften starch-containing embryogenic cells, and large, vacuolatednon-embryogenic cells. A presumed sequence of developmentalstages from single embryogenic cells to globular and heart-shapedstages of embyrogenesis was observed in the suspension cultures.Plantlets were produced from the embryoids when the suspensionswere plated in an agar medium without any hormone or with only0.2 mg 112, 4-D or naphthalene acetic acid. Embryogenicsuspension cultures derived from immature embryos as well asfrom inflorescence segments gave rise to plants which showedthe normal somatic chromosome number of 2n = 4x = 32. Panicum maximum Jacq., Guinea grass, embryogenesis, regeneration, suspension culture 相似文献
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