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Effects of H-ol and H-acid were observed using excised partsof several plant species. Both H-ol and H-acid were active inelongation of oat coleoptile and mesocotyl, expansion of Raphanusleaf disk, but were inactive in elongation of wheat coleoptileand of green stem of pea. They gave also negative results inthe standard Avena curvature test and in the split pea test.In expansion of lettuce cotyledon, H-ol was inactive while H-acidwas active. In excised plant parts, as in intact plants, theactivity of H-ol and H-acid resembles rather gibberellins thanauxins and cytokinins. (Received August 20, 1966; ) 相似文献
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- Investigations were made on the influence of inorganic nitrogenouscompounds upon the the germination of tobacco seeds (Nicotianatabacum L. var. virginica (AGDH.) COM. "Bright Yellow") inducedby GA3, kinetin and ammonium salts of organic acids. Potassiumnitrate, ammonium chloride, ammonium sulfate and ammonium nitrategreatly increase the germination of the seeds induced by theabove reagents, while these inorganic salts, given alone, arealmost ineffective in causing germination.
- Kinetin was shownto induce germination of tobacco seeds inthe dark. The discrepancywith the results of previous investigationsin this respectwas discussed.
- It was inferred that nitrogenous metabolismis involved in theprocess of dark-germination of tobacco seedsas induced by theabove-stated stimulating factors and promotedby inorganic nitrogenoussubstances.
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RICHARD P. SHEFFERSON CHARLES C. COWDEN MELISSA K. MCCORMICK TOMOHISA YUKAWA YUKI OGURA‐TSUJITA TOSHIMASA HASHIMOTO 《Molecular ecology》2010,19(14):3008-3017
Host breadth is often assumed to have no evolutionary significance in broad interactions because of the lack of cophylogenetic patterns between interacting species. Nonetheless, the breadth and suite of hosts utilized by one species may have adaptive value, particularly if it underlies a common ecological niche among hosts. Here, we present a preliminary assessment of the evolution of mycorrhizal specificity in 12 closely related orchid species (genera Goodyera and Hetaeria) using DNA‐based methods. We mapped specificity onto a plant phylogeny that we estimated to infer the evolutionary history of the mycorrhiza from the plant perspective, and hypothesized that phylogeny would explain a significant portion of the variance in specificity of plants on their host fungi. Sampled plants overwhelmingly associated with genus Ceratobasidium, but also occasionally with some ascomycetes. Ancestral mycorrhizal specificity was narrow in the orchids, and broadened rarely as Goodyera speciated. Statistical tests of phylogenetic inertia suggested some support for specificity varying with increasing phylogenetic distance, though only when the phylogenetic distance between suites of fungi interacting with each plant taxon were taken into account. These patterns suggest a role for phylogenetic conservatism in maintaining suits of fungal hosts among plants. We stress the evolutionary importance of host breadth in these organisms, and suggest that even generalists are likely to be constrained evolutionarily to maintaining associations with their symbionts. 相似文献
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