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521.
522.
Regulation of growth: the meristem network approach 总被引:2,自引:0,他引:2
G. N. AMZALLAG 《Plant, cell & environment》1999,22(5):483-493
Gibberellin (GA) and/or cytokinin (CK) supplied to the root medium modified the rate of growth of the shoot, the adventitious and seminal roots in young seedlings of Sorghum bicolor (L.) Moench. For each population submitted to a hormonal treatment, the link between the weight of these three organs was analysed. All these links build a network of relationships, also termed a meristem network. Treatments with 1–100 μ M CK modified the relative growth of these three organs, as well as the meristem network. Treatments with 1–100 μ M GA slightly modified the growth, but the meristem network was considerably changed. When GA and CK were applied simultaneously, the growth was similar to that of CK-treated plants, and the meristem network was similar to that of GA-treated plants. Similar experiments were performed on plants exposed to 150 m M NaCl. They showed that both growth and meristem networks are modified by salinity. Growth was unrelated to the network variations in non-salinized plants, while an optimal level of relationship for growth was observed in salinized plants. It is concluded that stress generates an imbalance between the self-stimulation of meristem activity and its regulation by the other organs. A definition of stress, independent from the rate of growth, is proposed. 相似文献
523.
[2H, 3H]Gibberellin A4 (GA4) or [2H, 3H] GA9 were applied to the shoot tips of seedlings of elongated internode (ein), a tall mutant of rapid cycling Brassica rapa. Following [2H]GA9 application, [2H]GA51, [2H]GA20 and [2H]GA4 were identified as products by GC-MS, while [2H]GA34 and [2H]GA1 were formed from [2H]GA4. Other isotopically labelled products, including abundant putative conjugates, were also produced, but were not identified. Thus, in B. rapa, GA1 biosynthesis involves the convergence of at least two metabolic pathways; it can be formed via GA4 or GA20, the latter of which can originate from GA9 or from GA19. 相似文献
524.
The effects of differential photoperiodic treatments applied to shoot tips and mature leaves of the long-day (LD) plant Silene armeria L. on growth and flowering responses, and on the levels of endogenous gibberellins (GAs), were investigated. Gibberellins were analyzed by gaschromatography-mass spectrometry and the use of internal standards. Exposure of mature leaves to LD, regardless of the photoperiodic conditions of the shoot tips, short days (SD), LD, or darkness, promoted elongation of the stems and of the immature leaves. Long-day treatment of the mature leaves modified the levels of endogenous GAs in shoot tips kept under LD, SD, or darkness. In shoot tips kept in LD or darkness the levels of GA53 were reduced, whereas the levels of GA19 and GA20 were increased. The contents of GA1 were increased in all three types of shoots: SD twofold, LD fivefold, and darkness eightfold. Dark treatment of the shoot tips on plants of which the mature leaves were grown in SD promoted elongation of the immature etiolated leaves and increased the GA1 content of the shoot tips threefold. However, this treatment did not cause stem elongation. The different photoperiodic treatments applied to the shoot tips did not change the levels of GAs in mature leaves. These results indicate that both LD and dark treatments result in an increase in GA1 in shoot tips. In addition, it is proposed that LD treatment induces the formation of a signal that is transmitted from mature leaves to shoot tips where it enhances the effect of GA on stem elongation.Abbreviations GAn
gibberellin An
- LD
long day(s)
- SD
short day(s)
We thank Dr. L.N. Mander, Australian National University, Canberra, for providing [2H]-gibberellins and Dr. D.A. Gage, MSU-NIH Mass Spectrometry Facility, East Lansing, for advice with mass spectrometry. This work was supported, in part, by a fellowship from the Spanish Ministry of Agriculture (Instituto Nacional de Investigaciones Agrarias) to M.T., by the U.S. Department of Energy grant No. DE-FG02-91ER20021, and by the U.S. Department of Agriculture grant No. 88-37261-3434 to J.A.D.Z. 相似文献
525.
Intact cells of a biotin-producing bacterium, KY–21–1–25, were found to synthesize biotin from dethiobiotin. Optimal conditions for the biosynthesis of biotin from dethiobiotin by intact cells were investigated. Intact cells harvested from adenine-supplemented medium showed intensive biosynthesis. However, the biosynthesis of biotin by intact cells was strongly inhibited by the addition of adenine or adenosine. The inhibitory activity of adenine was about 10-fold greater than that of adenosine. Formation of several unidentified biotin-vitamers was observed in both reaction mixtures incubated with and/or without addition of adenine. 相似文献
526.
The development of sensitive and specific solid-phase enzyme immunoassays for gibberellic acid and gibberellins A4 and A7 is reported. The use of antisera of high apparent affinity (Ka over 1010 l mol-1) in conjunction with alkaline phosphatase-labeled gibberellins allows, with minimum procedural effort, the quantitative determination of sub-picogram amounts of these gibberellins. The assays reported here are applicable to most gibberellins and can be set up with 1–1.5 mg of starting material. They represent the most sensitive methods for gibberellin determination known.Abbreviations GA
gibberellin
- GA3
gibberellic acid
- TLC
thin-layer-chromatography 相似文献