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The development of lateral buds in isolated stems of Coleus blumei is inhibited by low concentrations of indoleacetic acid or other auxins, just as in other plants. The inhibition can be fully reversed by kinetin, about 3 times as much kinetin as IAA being needed. However, the outgrowth of the same lateral buds on intact Coleus plants is sensitive to environmental conditions, well-nourished plants in full daylight often showing little inhibition by applied auxin. It is shown that (a) the solvent used for IAA, (b) the light intensity and (c) the nitrogen and phosphorus nutrition, all control the sensitivity of the buds to auxin inhibition. Using water instead of lanolin, lowering the light intensity or decreasing the supply of either nitrogen or phosphorus all increase the degree of apical dominance. 相似文献
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The effects of hormones on sucrose distribution were studiedin relation to the control of the relative growth of the shootand the root. The roots and the shoots above the cotyledonsof bean seedlings were removed and the remaining explants allowedto regenerate so that they consisted of growing buds, a segmentof the hypocotyl, and short growing roots. [14C]Sucrose wasapplied to the middle of the hypocotyl and its distributionwas measured in relation to the presence of the shoots and rootsand to their replacement by auxin and a cytokinin. It was foundthat radioactivity moved towards both the shoot and the root,and that removing one growing region greatly reduced the transportin its direction and increased the relative transport in theopposite direction. Both hormones restored a large part of themovement of radioactive sucrose when they replaced any one ofthe growing regions. However, there was some preferential actionof benzyladenine when it replaced the buds and of auxin whenit replaced the roots. The results indicate that in the intactplant the development of the shoot and the root is correlatedby a positive feedback involving auxin and cytokinins, and themovement of sucrose is controlled indirectly by the sink activityof these growing regions. This control of the movement of sucrose,and presumably other metabolites, accounts for the short-termcompetitive relations between the shoot and the root. 相似文献
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W. BOOTH S. M. BOGDANOWICZ P. A. PROD
HL R. G. HARRISON C. SCHAL E. L. VARGO 《Molecular ecology resources》2007,7(4):648-650
Primer sequences and initial characterization are presented for 10 microsatellite loci isolated from the German cockroach, Blattella germanica. In a sample of 30 individuals from a single population sample, all loci were polymorphic with two to 12 alleles segregating per locus and levels of observed heterozygosity ranging from 0.27 to 0.92. One locus showed a deficit of heterozygotes. Experimental conditions are described for polymerase chain reaction multiplexing, which enables the genotyping of eight loci in three electrophoretic runs consisting of one set of three and two sets of two markers. Seven primer sets cross‐amplify in the related Blattella asahinai. 相似文献
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J. L. SACHS J. E. RUSSELL Y. E. LII K. C. BLACK G. LOPEZ A. S. PATIL 《Journal of evolutionary biology》2010,23(9):1919-1927
Host control mechanisms are thought to be critical for selecting against cheater mutants in symbiont populations. Here, we provide the first experimental test of a legume host’s ability to constrain the infection and proliferation of a native‐occurring rhizobial cheater. Lotus strigosus hosts were experimentally inoculated with pairs of Bradyrhizobium strains that naturally vary in symbiotic benefit, including a cheater strain that proliferates in the roots of singly infected hosts, yet provides zero growth benefits. Within co‐infected hosts, the cheater exhibited lower infection rates than competing beneficial strains and grew to smaller population sizes within those nodules. In vitro assays revealed that infection‐rate differences among competing strains were not caused by variation in rhizobial growth rate or interstrain toxicity. These results can explain how a rapidly growing cheater symbiont – that exhibits a massive fitness advantage in single infections – can be prevented from sweeping through a beneficial population of symbionts. 相似文献