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101.
102.
Optimization of in vitro tuberization (formation and growth of stolons and microtubers) by synchronization of cell divisions in axillary meristems of initial stem explants induced by low nonfreezing temperatures was studied in potato (Solanum tuberosum L., cv. Lugovskoi) plants. The proportion of simultaneously dividing cells in axillary meristems of stem explants subjected to 2-h cold treatment at 4°C was in 2.6 times greater than in control material (without chilling). The analysis of growth of stolons and microtubers produced from the explants exposed to cold showed that synchronization of cell divisions in the meristems of initial explants resulted in synchronization of stolon and microtuber formation and production of microtubers of identical physiological age. 相似文献
103.
Podostemaceae are unusual aquatic angiosperms adapting to extreme habitats, i.e., rapids and waterfalls, and have unique morphologies. We investigated the developmental anatomy of reproductive shoots scattered on crustose roots of Hydrobryum japonicum by scanning electron microscopy and using semi-thin serial sections. Two developmental patterns were observed: bracts arise either continuously from an area of meristematic cells that has produced leaves, or within differentiated root ground tissue beneath, and internal to, leaf base scars after an interruption. In both patterns, the bract primordia arise endogenously at the base of youngest bracts in the absence of shoot apical meristem, involving vacuolated-cell detachment to each bract separately. The different transition patterns of reproductive shoot development may be caused by different stages of parental vegetative shoots. The floral meristem arises between the two youngest bracts, and is similarly accompanied by cell degeneration. In contrast, the floral organs, including the spathella, arise exogenously from the meristem. Bract development, like vegetative leaf development, is unique to this podostemad, while floral-organ development is conserved. 相似文献
104.
105.
Regulatory networks that function to specify flower meristems require the function of homeobox genes PENNYWISE and POUND-FOOLISH in Arabidopsis 总被引:1,自引:0,他引:1
Kanrar S Bhattacharya M Arthur B Courtier J Smith HM 《The Plant journal : for cell and molecular biology》2008,54(5):924-937
Flowering is a major developmental phase change that transforms the fate of the shoot apical meristem (SAM) from a leaf-bearing vegetative meristem to that of a flower-producing inflorescence meristem. In Arabidopsis, floral meristems are specified on the periphery of the inflorescence meristem by the combined activities of the FLOWERING LOCUS T (FT)–FD complex and the flower meristem identity gene, LEAFY ( LFY ). Two redundant functioning homeobox genes, PENNYWISE ( PNY ) and POUND-FOOLISH ( PNF ), which are expressed in the vegetative and inflorescence SAM, regulate patterning events during reproductive development, including floral specification. To determine the role of PNY and PNF in the floral specification network, we characterized the genetic relationship of these homeobox genes with LFY and FT . Results from this study demonstrate that LFY functions downstream of PNY and PNF. Ectopic expression of LFY promotes flower formation in pny pnf plants, while the flower specification activity of ectopic FT is severely attenuated. Genetic analysis shows that when mutations in pny and pnf genes are combined with lfy , a synergistic phenotype is displayed that significantly reduces floral specification and alters inflorescence patterning events. In conclusion, results from this study support a model in which PNY and PNF promote LFY expression during reproductive development. At the same time, the flower formation activity of FT is dependent upon the function of PNY and PNF. 相似文献
106.
107.
N. P. Demchenko I. B. Kalimova K. N. Demchenko 《Russian Journal of Plant Physiology》2005,52(2):220-228
The effect of 10–6 and 10–4 M NiSO4 on cell growth, proliferation, and differentiation was studied over 48 h in seminal and lateral roots of five-day-old Triticum aestivum seedlings. 10–6 M NiSO4 did not significantly affect the root system, whereas 10–4 M NiSO4 inhibited its development. However, 10–6 M NiSO4 disturbed the contacts between the groups of closely related cells of the rhizodermis in the meristem. In the exodermis, an additional layer of cells was formed. At the nickel concentration of 10–4 M, cell divisions in the outer layers of the root cells and metaxylem ceased earlier than in other root tissues positioned both centripetally and acropetally. Differentiation of protophloem sieve elements was completed in the meristem but at a greater distance from the root tip. Cell elongation started at the same distance from the root tip as in control plants. The rate of elongation decreased, and acropetally it stopped. Therefore, the cells of the xylem and metaphloem started to differentiate, and primordia of lateral roots were initiated and formed closer to the root tip. At a lethal concentration (10–4 M), nickel induced necroses of elongating cells of the endodermis and pericycle. Nickel is supposed to enter the tissues of the central cylinder predominantly via the protoxylem and rapidly translocate along the xylem. As a result, the incubation of the roots at this concentration for 48 h almost did not affect the development of the phloem and probably sugar unloading, that makes possible to maintain the growth of meristematic cells and the cell division of the most important tissues for longer time.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 250–258.Original Russian Text Copyright © 2005 by N. Demchenko, Kalimova, K. Demchenko.This revised version was published online in April 2005 with a corrected cover date. 相似文献
108.
Cymbopogon nardus L. could be propagated via tissue culture using axillary buds as explants. The aseptic bud explants obtained using double
sterilization methods produced stunted abnormal multiple shoots when they were cultured on Murashige and Skoog medium (MS)
supplemented with 1.0 mg L-1 or 2.0 mg L-1 benzyladenine (BA). Stunted shoots that cultured on MS + 1.0 mg L-1 BA + 1.0 mg L-1 N6-isopentenyl-adenine (2iP) could induce elongation of shoots from about 60% of the stunted shoots. Normal multiple shoots
could be induced at the highest (19.7 shoots per bud) from the bud explants within six weeks when cultured on proliferation
medium consisted of MS supplemented with 0.3 mg L-1 BA and 0.1 mg L-1 indole-3-butyric acid (IBA). The separated individual shoot produced roots when transferred to basic MS solid medium. The
essential oils that were contained in the mature plants namely citronellal, geraniol and citronellol were also found in thein vitro C. nardus plantlets. Citronellal was the main essential oil component in the matured plants while geraniol was the main component in
thein vitro plantlets. 相似文献
109.
110.
Lavandin (Lavandula dentata) axillary buds were grown in Linsmaier-Skoog (LS) medium solidified with 10 % bactoagar (control) and supplemented with 0.1 mg dm–3 benzyladenine (BA), 0.1 mg dm–3 indolebutyric acid (IBA) or both plant growth regulators. In the studied conditions the axillary buds developed into plantlets. The addition of BA inhibited the formation of glands by 44 % as compared with the control plantlets and also inhibited their development: these plantlets had the highest number of unbroken glands (in pre-secretory state) when compared with plantlets grown in the other conditions. The presence of BA stimulated chloroplast formation, and increased the content of essential oils by 150 % with respect to the control plantlets. It also increased their secretion, and the number of lipid droplets in the chloroplasts, cytosol and plasmalemma. On the contrary, the presence of IBA decreased the essential oil concentration in plantlets by 31 % when compared with the control ones and inhibited their secretion capacity. 相似文献