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1.
V. Grant 《Plant Systematics and Evolution》2001,230(1-2):89-96
This paper deals with the use of cladistic methods and cladograms in phylogeny reconstruction in plant groups containing
numerous taxa. How accurate are the cladograms as to details? Accuracy tests at the level of details require an independently
known phylogeny, which excludes most plant groups, but such tests can be carried out in domesticated and experimental plant
groups which have documented pedigrees. Four such tests are known and are presented here: a new case in Gilia and three previously published cases in Avena, Hordeum, and Helianthus. The four cases include domesticated and experimental plants, use of morphological and molecular evidence, and presence of
dichotomous as well as reticulate phylogenies. The cladograms of the four plant groups all differ in significant details from
the known pedigrees. These results are discussed in relation to problems of interpretation of cladograms.
Received March 21, 2000 Accepted August 16, 2001 相似文献
2.
3.
J. Yamaguchi S. Itoh T. Saitoh A. Ikeda T. Tashiro Y. Nagato 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(1):32-38
β-Amylase deficiency in various cultivars of rice was examined at the molecular level. Using an antibody against β-amylase
purified from germinating seeds of rice, we were able to demonstrate the expression and organization of the β-amylase gene
in normal and deficient cultivars. Although β-amylase is a starch-hydrolyzing enzyme, as is α-amylase, the β-amylase protein/gene
is expressed differently from the α-amylase protein/gene; i.e. (1) β-amylase is synthesized only in aleurone cells, (2) the
enzyme production in the embryo-less half-seeds is not under hormonal control. We identified some cultivars of rice that are
deficient for β-amylase activity. We present new evidence that synthesis is blocked at the level of mRNA synthesis in the
deficient cultivars. The usefulness of β-amylase as a crop trait is also discussed.
Received: 8 May 1998 / Accepted: 5 June 1998 相似文献
4.
Supply and partitioning of assimilates to roots of Medicago sativa L. and Lotus corniculatus L. under anoxia 总被引:3,自引:0,他引:3
A. L. BARTA 《Plant, cell & environment》1987,10(2):151-156
Abstract A current explanation of the mechanism of flooding injury to roots suggests that oxygen deficiency depresses the supply of respirable carbohydrates sufficiently to inhibit fermentation. However, even though it has been shown that phloem transport of assimilate is sharply reduced to anaerobic roots, inhibition of assimilate metabolism has also been suggested to be an important factor. This study examines these hypotheses by relating assimilate supply and metabolic activity in anoxic roots of alfalfa (Medicago sativa L.), a flood-intolerant species, and birdsfoot trefoil (Lotus corniculatus L.), a flood-tolerant plant. Roots were made anoxic (severe O2 deficiency) for 2, 4 or 6 d and shoots were labelled with 14CO2. Assimilate transport to the roots and metabolism to structural components were significantly decreased in both species in response to anoxia. Trefoil exhibited significantly greater 14C incorporation into the residue fraction at 4 d anoxia than did alfalfa, and this was consistent with the greater flooding tolerance of trefoil. When assimilate supply to O2-deficient roots was decreased by shoot shading, shoot fresh weight was reduced by both anoxia and light treatments. Root-soluble sugars were significantly decreased by shading but were greatly increased in response to anoxia. Root starch concentration also increased under anoxia. Root K+ concentration was reduced by anoxia only. The energy status (ATP/ADP) of roots was significantly decreased by shading; however, anoxia reduced the energy status only in unshaded plants. The data indicate that carbohydrate supply to anaerobic roots does not appear to be a limiting factor in the metabolic response of alfalfa roots. Alternatively, metabolism of assimilate in anoxic roots may be an important determinant of survival. 相似文献
5.
6.
Martina Weber 《Plant Systematics and Evolution》1988,161(1-2):53-64
The formation of sperm cells has been examined ultrastructurally in the tricellular pollen grains ofGalium mollugo L. (Rubiaceae).Trichodiadema setuliferum
Schwantes (Aizoaceae), andAvena sativa L. (Poaceae). After detachement from the intine the generative cell of all three species lies free within the vegetative cytoplasm. The two sperm cells are built inTrichodiadema andAvena by a single separating wall, while inGalium mollugo two independent walls are formed. However, both mechanisms separate the two male gametes completely. 相似文献
7.
Michael Gjedde Palmgren Marianne Sommarin Peter Leth Jørgensen 《Physiologia plantarum》1988,74(1):20-25
Plasma membrane vesicles with H+ -ATPase activity were purified from 8-day-old oat ( Avena sativa L. cv. Brighton) roots using an aqueous polymer two-phase system. Of several detergents tested, only lysophosphatidylcholine solubilized the H+ -ATPase in an active form. Solubilization of the H+ -ATPase with lysophosphatidylcholine was possible in the absence of glycerol, but the ATPase activity decreased about 4–5 times as rapidly in the absence as in the presence of 30% (w/v) glycerol. The solubilized enzyme was further stabilized by ATP and protons. Addition of 1 m M ATP to the plasma membranes halted inactivation of the H+ -ATPase. Even in the absence of polyol compounds and ATP, the enzyme was stable for hours at relatively low pH with an optimum around pH 6.7 at room temperature. The curve for the stability of soluble H+ -ATPase as a function of pH closely resembles the pH curve for the activity of the H+ -ATPase. This suggests that binding of protons to transport sites may stabilize the soluble H+ -ATPase in an enzymatically active form. 相似文献
8.
Phytochrome is not involved in the red-light-enhancement of the stomatal blue-light-response in wheat seedlings 总被引:2,自引:0,他引:2
Per Erik Karlsson 《Physiologia plantarum》1988,74(3):544-548
The stomatal response to blue light (BL) in wheat seedlings ( Triticum aestivum L. cv. Starke II, Weibull) was enhanced by background red light (R). This enhancement was only slightly affected by the addition of background far-red light (FR). Under similar light treatments, the addition of FR induced a 43% transformation from the far-red-absorbing form towards the red-absorbing form of phytochrome from etiolated oat ( Avena sativa L. cv. Sol II), immobilized on phenyl-sepharose. Furthermore, the enhancement of the stomatal BL-response by 15 min R was not reversed by a subsequent irradiation with 5 min FR. It is concluded that the red-light-enhancement of the stomatal blue-light-response in wheat seedlings does not involve a change in the photostationary state of phytochrome. 相似文献
9.
Light gradients and spectral regime were measured in Lactuca sativa L. cv. Grand Rapids achenes using fiber optic microsensors. The distribution of scattered light across lettuce achenes was linear for 660 and 730 nm and non-linear for 450 nm light. Spectra for scattered light within intact achenes also showed a non-linear increase with wavelength. The preferential attenuation of blue light by the pericarp and seed explains in part the relative ineffectiveness of blue light with respect to red in triggering germination of lettuce. Calculated action spectra for phytochrome-stimulated germination agree closely in the red with experimentally derived action spectra; however, there is little agreement within the blue. 相似文献
10.
Michael Gjedde Palmgren Marianne Sommarin Peter Ulvlskov Peter Leth Jørgensen 《Physiologia plantarum》1988,74(1):11-19
Plasma membrane vesicles were purified from 8-day-old oat ( Avena sativa L. cv. Brighton) roots in an aqueous polymer two-phase system. The plasma membranes possessed high specific ATPase activity [ca 4 μmol P1 (mg protein)−1 min−1 at 37°C]. Addition of lysophosphatidylcholine (lyso-PC) produced a 2–3 fold activation of the plasma membrane ATPase, an effect due both to exposure of latent ATP binding sites and to a true activation of the enzyme. Lipid activation increased the affinity for ATP and caused a shift of the pH optimum of the H+ -ATPase activity to 6.75 as compared to pH 6.45 for the negative H+ -ATPase. Activation was dependent on the chain length of the acyl group of the lyso-PC, with maximal activition obtained by palmitoyl lyso-PC. Free fatty acids also activated the membrane-bound H+ -ATPase. This activation was also dependent on chain length and to the degree of unsaturation, with linolenic and arachidonic acid as the most efficient fatty acids. Exogenously added PC was hydrolyzed to lyso-PC and free fatty acids by an enzyme in the plasma membrane preparation, presumably of the phospholipase A type. Both lyso-PC and free fatty acids are products of phospholipase A2 (EC 3.1.1.4) action, and addition of phospholipase A2 from animal sources increased the H+ -ATPase activity within seconds. Interaction with lipids and fatty acids could thus be part of the regulatory system for H+ -ATPase activity in vivo, and the endogenous phospholipase may be involved in the regulation of the H+ -ATPase activity in the plasma membranne. 相似文献