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961.
Shoot regeneration from seed-derived callus cultures of Kentucky bluegrass (Poa pratensis L.) was tested on MS basal medium supplemented with four different growth regulators. Regeneration frequencies for medium supplemented with 10 M 2,4-dichlorophenoxyacetic acid (2,4-D), 60 M 4amino-3, 5,6-picolinic acid (picloram), or 30 M 3,6dichloro-o-anisic acid (dicamba) ranged from 0.4 to 4%. Medium supplemented with 30 M dicamba plus 10 M 6-benzylaminopurine (BA) resulted in regeneration of shoots from 20% of the calli tested. Higher rates of growth regulators (60 or 90 M dicamba, 20 M BA) resulted in regeneration of shoots from 45% of calli of the cultivar Baron. In a subsequent study, the response of 12 North American cultivars grown on these media was cultivar-specific, with mean frequencies of regeneration ranging from 4% to 40%.Abbreviations 2,4-D
2,4-dichlorophenoxyaceticacid
- dicamba
3,6-dichloro-o-anisic acid
- picloram
4-amino-3,5,6-picolinic acid
- BA
6-benzylaminopurine 相似文献
962.
Enhanced plant regeneration in grain and sweet sorghum by asparagine,proline and cefotaxime 总被引:7,自引:0,他引:7
Summary Cefotaxime ( 50 and 100 mg/1 ), a cephalosporin antibiotic and the amino acids asparagine and proline (200 mg/l) enhanced the production of embryogenic callus, increased the frequency of plant regeneration, and delayed the loss of regeneration potential in immature embryo-derived callus cultures ofSorghum bicolor (L.) Moench. Although these compounds did not promote callus induction or growth of callus, they influenced plant regeneration considerably in 10 low responding genotypes of grain and high anthocyanin containing sweet sorghums. 相似文献
963.
Protoplasts derived from tissue-cultured shoot primordia of garlic (Allium sativum L.) initiated successive cell divisions within 4 days and formed small individual calli (0.2mm in diameter) after 5 weeks of culture on Gamborg's B5 medium supplemented with 0.1% casein hydrolysate, 1mg/1 1-naphthaleneacetic acid and 1mg/1 6-benzylaminopurine. Plating efficiency was roughly 5% at the density of 1x104 protoplasts/ml of medium. Adventitious buds developed from the calli during subsequent subculture on Gamborg's B5 medium supplemented with 40mg/l adenine and 10% coconut milk. When transferred to the same medium without supplements, these buds grew into shoots and rooted. The regenerated garlic plantlets were successfully transferred to the greenhouse and grew into whole plants. 相似文献
964.
Tomomi Nakamoto 《Journal of plant research》1995,108(1):71-75
The growth of the primary seminal root of maize (Zea mays L.) is characterized by an initial negative gravitropic reaction and a later positive one that attains a plagiotropic liminal
angle. The effects of temperature and water potential of the surrounding soil on these gravitropic reactions were studied.
Temperatures of 32, 25, and 18C and soil water potentials of −5,−38, and −67 kPa were imposed and the direction of growth
was measured for every 1 cm length of the root. The initial negative gravitropic reaction extended to a distance of about
10cm from the graln. Higher temperatures reduced the initial negative gravitropic reaction. Lower soil water potential induced
a downward growth at root emergence. A mathematical model, in which it was assumed that the rate of the directional change
of root growth was a sum of a time-dependent negative gravitropic reaction and an establishment of the liminal angle, adequately
fitted the distance-angle relations. It was suggested that higher temperatures and/or a lower water potential accelerated
the diminution of the intitial negative gravitropic reaction. 相似文献
965.
M. Teresa García-López Ibon Alkorta M. José Domínguez Rosario González-Mu?iz Rosario Herranz Nils L. Johansen Kjeld Madsen Henning Th?gersen Peter Suzdak 《Letters in Peptide Science》1995,1(6):269-276
Summary In order to enforce different spatial orientations in the C-terminal hexapeptide of neurotensin (NT8–13) and to gain information about the importance of the 10–11 peptide bond for binding to NT receptors, the Pro10-Tyr11 fragment has been replaced with (2R,8S,8aR)-, (2S,8S,8aR)-, (2S,8S,8aS)-, (2S,8R,8aS)- and (2R,8R,8aS)-8-amino-2-benzyl-3-oxoindolizidine-2-carboxylic acid. Molecular dynamics calculations and energy minimization studies have shown that, contrarily to the Pro-Tyr moiety, none of these indolizidines display a tendency to adopt type I and III -turns, but those having (8S,8aR) or (8R,8aS) stereochemistry essentially adopt extended conformations and the (8S,8aS) stereoisomer prefers a nonstandard folding. The four diastereomeric NT8–13 analogues incorporating (8S,8aR) or (8R,8aS) indolizidines displayed binding affinities for the brain NT receptor similar to that of [Ala11]-NT8–13 and only five- to ninefold lower than that of the corresponding analogue, [Phe11]NT8–13. Although this slight decrease could be attributed to differences in conformational behavior between these constrained NT8–13 analogues and [Phe11]NT8–13 or NT8–13, it is not clear whether the -turn around Pro10-AA11 (AA=Phe, Tyr) is conserved upon receptor binding. An excessive restriction in the motions of the aromatic side chain, imposed by the highly steric constraint of the indolizidine moiety, emerges as an alternative explanation. The findings reported here demonstrate the possibility of replacing the Pro10-Tyr11 dipeptide in NT8–13 with a non-peptide residue without affecting considerably the affinity for brain NT receptors. 相似文献
966.
The effects of aluminium chloride (AICI3) treatments (50 and 150 mg/l) on 3-year-old Scots pine (Pinus sylvestris L.) seedlings were studied in a sand culture during 2 growing periods in an open field experiment. Even by the end of the
first growing period, a decline was observed in the concentrations of Ca, Mg and P within the needles, and of Ca and Mg in
the roots. After the second growing period, increased N and K concentrations were observed in the needles of Al-treated seedlings.
Both the needles and roots of Al-treated seedlings showed, after the second growing period, a decline in growth and increased
concentrations of AI as the amount of AICI3 in the nutrient solution increased. Al-induced changes in needle structure were
found to be symptomatic of a nutrient imbalance, particularly of Mg and P. Al-stress did not result in any observable changes
in root anatomy or in the number of mycorrhizas. Scots pine proved to be rather resistant to Al-stress, indicating that direct
Al-injuries are not likely in the field, though Al-stress may be a contributing factor in the formation of nutrient imbalances. 相似文献
967.
The basic anatomy of lateral twig insertion onto the main branch in both healthy and damaged Quercus cerris L. trees was studied. An abscission zone is always present: in healthy trees it is formed by a smaller number of cell layers than in damaged ones, where it is more evident with many layers of cells. Cells of the abscission zone are roundish, with many intercellular spaces between them; cell walls are thin, non-lignified and without secondary walls. No starch was found in cells of the abscission zone, where, instead, a few scattered calcium oxalate druses are seen. 相似文献
968.
Michael Trockenbrodt 《Trees - Structure and Function》1995,9(6):341-347
The root bark structure of Quercus robur L. was analysed at different stages of root development and compared to the structure of stem bark. Root bark thickness varied considerably between different roots. Sclereid quantity decreased with increasing distance from the stem, which means it increased with age. Visible growth increments diminished with increasing distance from the stem. In lateral roots crystal quantity decreased with increasing distance from the stem. In lateral roots secondary phloem fibre length, sieve tube member length, and sieve tube diameter showed no regular trend. There were only a few basic structural differences between root and stem bark. The zone of cell differentiation (cell expansion, lignification) was wider in root bark; sieve tube collapse was delayed. In lateral root bark fewer sclereids were formed. The first-formed periderm often originated from deeper cell layers. Thus, primary elements were lacking after periderm formation. In root bark the phellem cell walls were of equal thickness. Thus, phellem lacked visible growth increments. Root bark phellem cells were slightly larger. The root phelloderm was more distinct. The secondary phloem fibres were slightly shorter than those in stem bark. Sieve tube members of stem and root bark were of similar length and diameter. The qualitative bark anatomical characters of oak root bark are suitable for root identifications. Due to minor structural differences between root and stem bark the characters must be used with care. 相似文献
969.
An examination was made of the structure of the coats of Scots pine (Pinus sylvestris L.) seeds of different provenance and the contribution of this factor to differences in imbibition. The seed coat layers
derived from the integument, the sarcotesta, sclerotesta and endotesta did little to restrict imbibition, even though the
sclerotesta of the northern provenance seeds was composed of a double multicellular layer and the sarcotesta contained large
numbers of pigmented, phenol-bearing cells. In addition to the micropyle, the sclerotesta was found to possess structural
openings at the chalazal end and at the ridge joining the two halves of the seed, but being covered by the pigmented cells
of the sarcotesta, these did not allow water to enter any more than did the micropyle itself. Imbibition was chiefly regulated
by the lipophilic covers surrounding the endosperm, which are mainly of nucellar origin, especially by the megaspore membranes
nearest to the endosperm, the outer and inner exine. The nucellar cap covering the micropylar end of the endosperm proved
to be impermeable to water, and its edge extended between the exine layers, which further enhanced the importance of the endosperm
covers as regulators of imbibition. 相似文献
970.
利用灵敏度高,专一性强的放射免疫法(RIA)测定了苦瓜和瓜萎不同器官中皮质醇的含量。结果表明:苦瓜和瓜萎各器官均含有皮质醇,且含量在50~450ng/g.FW;顶芽中含量最高,其次是花器官;苦瓜和瓜篓雌花皮质醇含量明显高于雄花,且雌花在授粉后当天含量最高,说明皮质醇可能在植物的生长发育过程中起某种作用。 相似文献