摘要:

Two analytical methods for measuring betaine were compared in a study of betaine accumulation in salt‐stressed sorghum. Spectrophotometric determination of betaine as thep‐bromophenacyl ester is highly sensitive and specific. However, a periodide assay was found to be more convenient for screening numerous plant samples without undue sacrifice in accuracy.The accumulation of betaine in grain sorghum [Sorghum bicolor(L.) Moench] cvs NK 265 and Double TX was measured in salt‐stressed plants grown hydroponically and in the field and in drought‐stressed potted plants. Neither drought nor mild salinity (‐0.2 MPa) stress was effective in stimulating betaine accumulation. However, when the osmotic potential of the culture solution was lowered to ‐0.8 MPa, betaine levels in the shoots rose rapidly for 12 days after initiation of salination, and then declined, apparently because of dilution by plant growth. In young leaf blades, betaine was strongly accumulated up to 70–75 μmol (g dry weight)−1; the concentration in leaf sheaths was less than 6 μmol (g dry weight)−1.In the field, betaine levels in salt‐stressed sorghum increased 6‐ to 7‐fold over the basal level of the control plants. In a comparable study of two wheat species (Triticum aestivumL. cv. Probred andT. durumDesf. cv. 1000‐D), betaine increased only 3‐ to

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05892.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Sugar and amino acid transport into empty ovules ofPisum sativumL. cv. Marzia was examined. In fruits containing 4–6 developing seeds, the embryo was removed from four ovules. After this surgical treatment, each empty seed coat was filled with a solution (pH 5.5) containing a low (0, 50 or 200 mM), medium (350, 400 or 500 mM) or high (0.7 or 1M) concentration of sucrose and/or mannitol. In pulse‐labelling experiments with sucrose and α‐aminoisobutyric acid (AIB), transport of sucrose and AIB into an empty ovule filled with a solution containing a high sucrose concentration was the same as transport into an ovule filled with a mannitol solution of similar osmolarity, demonstrating that a high sucrose concentration in the seed coat apoplast affects phloem transport of sucrose and AIB into the seed coat only by the osmotic effect. The osmolarity of a given solution filling the seed coat cavity appeared to be important for phloem transport of sucrose and AIB into empty ovules.In our experiments, 350 mMappeared to be the optimal concentration for sucrose and AIB transport into the cavity within an empty ovule, giving results comparable with transport into intact ovules. A lower osmolarity of the solution induced less transport. Very high sucrose or mannitol concentrations caused a strong inhibition of sucrose and AIB unloading from the seed coat, so that transport into the empty ovules was inhibited. A low (strongly negative) but not too low osmotic potential of the solution in the seed coat apoplast seems necessary to maintain a normal rate of phloem transport into developing seeds. Apparently, the “sink strength” of developing seeds is turgor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05893.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The carboxanilide systemic fungicide 2‐iodobenzanilide (2‐IB) after 2 h pretreatment at 0.25 mMinhibited K+and SO42‐uptake by excised corn roots (Zea maysL., cv. Dekalb 342) up to ca 70 and 40%, respectively. Proton extrusion from corn roots was also reduced by ca 50% after 1 h contact, and the microsomal K+‐stimulated ATPase activity from corn roots and pea stems (Pisum sativumL., cv. Alaska) inhibited by 50 and 72%, respectively. In contrast, the Mg2+‐ATPase activities of microsomes and mitochondria at pH 6.0 and 8.7, respectively, were unaffected. After 2 h of preincubation with 0.25 mM2‐IB, O2consumption by corn roots and pea stems was inhibited by 12 and 18%, respectively. ATP content of corn roots was not altered by 2‐IB treatment. Therefore, energy availability “in vivo” was unaffected and the primary effect on corn roots is suggested to be at the plasmalemma ATPase which forms the proton gradient.With isolated pea stem mitochondria, 0.25 mM2‐IB inhibited O2consumption by ca 60% when NADH or malate plus pyruvate were added as substrates; when succinate was used O2consumption was unaffected. The mode of action on isolated mitochondria was different from that shown for carboxin and also formerly attributed to the whole class of carbo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05894.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Dormant tuber tissue of Jerusalem artichoke (Helianthus tuberosusL.) can be stimulated by wounding to initiate RNA and protein synthesis. No DNA synthesis or cell divisions occur unless an auxin is provided. Changes in polysomal profiles and levels of Poly(A)+‐RNA in response to wounding and auxin treatment were studied. Polysomes were isolated at various times after excision and incubation of tissue in the presence or absence of 10−5M2,4‐dichlorophenoxyacetic acid. Polysomal profiles were studied by sucrose density gradient centrifugation. Dormant tissue contained ribosomes mainly in monosome form. Within 4 h of excision, a significant increase in the polysomal fraction was observed both in control and auxin‐treated tissue. Increases in polysomes continued during the next 20 h. Poly(A)+‐RNA was isolated from total polysomal RNA by oligo(dT)‐cellulose column chromatography. There was a large increase in the amount of poly(A)+‐RNA within 4 h of excision. During the first 43 h of incubation, levels of total polysomal RNA as well as poly(A)+‐RNA in tissue treated with 2,4‐dichlorophenoxyacetic acid were significantly higher than

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05895.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The glycinebetaine content of plants can be determined by simple isocratic high performance liquid chromatography. The method is applicable to extracts from a wide range of species and, in most cases, is suitably rapid and specific to be preferable to other methods of analysis. The chromatographic system employed permits accurate and sensitive ultraviolet detection, free of most interferences. Because the principle plant carbohydrates elute well before glycine betaine, preparative ion exchange procedures can be simplified. Twenty‐seven species, mostly inland halophytes, were screened by these methods and 13 were found to be glycinebetaine accumulators. On a dry weight basis, the glycinebetaine content ofSalicornia europaeaL. actually declined with exposure to progressively higher levels of NaCl. When expressed as a proportion of plant organic matter, however, patterns were more typical (up to 7.7% at higher salt concentrations

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05896.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Comparing nutrient translocation to the rice (Oryza sativaL. var.Arborio) shoot during anoxia with the aerobic situation, it was found that anoxia reduced the translocation of K+, phosphorus, Mg2+and Ca2+with progressive intensity; Ca2+translocation was practically zero in the absence of oxygen. The translocation of K+and phosphorus under anoxia was still considerable and contributed to the maintenance of a high osmotic potential while the blocking of Ca2+translocation caused a decrease in its concentration in the anoxic coleoptile, possibly favouring high cell wall plasticity in that organ. As anoxia proceeded, amino acids, no longer employed in protein synthesis, accumulated in the coleoptile, reaching spectacular levels [51 mmol kg of tissue‐water)−1] and, after 48 h of anoxia, their contribution to the osmotic potential was 80% of that of K+, as against less than 20% in all aerobic treatments. Anoxia caused a reduction in soluble hexose concentrations which, however, were more than compensated osmotically by the accumulation of amino ac

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05897.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The coleoptile curvature bioassay of agar diffusates from successive cambial‐region sections ofPinus silvestrisL. stem tissue reveals the existence of a wave‐like pattern, possibly of auxin translocation. Spectrofluorometric determinations of indolyl‐3‐acetic acid (IAA) in these diffusates gave only a poor correlation. Probably another phytohormone, also an auxin, plays a more important role in the pattern.The amplification in the amplitude of the pattern, brought about by apically applied IAA, cannot be induced by the synthetic auxin, 2,4‐dichlorophenoxyac

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05898.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Diurnal variations of in vitro activity of 5 enzymes of nitrogen metabolism were studied. Barley (Hordeum vulgareL. cv. Herta) seedlings were grown in 8 h short days, in daylight or under fluorescent lamps. During, the photoperiod nitrite reductase (EC 1.7.7.1) increased by an average of 18% in daylight and 10% under fluorescent lamps. Glutamine synthetase (EC 6.3.1.2) activity increased by 14 and 10%, respectively. The increase in enzyme activity reflected the overall increase in soluble proteins which was 8% in daylight and 3% under fluorescent lamps. Alanine aminotransferase (EC 2.6.1.2) increased by 82% in daylight and 37% under fluorescent lamps. Desalting of the extracts did not alter the enzyme activity and thus supported the assumption that changes in extractable enzyme activity are due to changes in the amount of (active) enzyme protein. Glutamate synthase (EC 1.4.7.1) activity did not show regular diurnal variations, and aspartate aminotransferase (EC 2.6.1.1) activity was almost constant.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05899.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Nitrate reductase (EC 1.6.6.1) activity showed circadian rhythmicity in the first leaf of 8–11 days old barley (Hordeum vulgareL. cv. Herta) plants. Circadian rhythms were found using both the in vitro and in vivo method for testing the enzyme activity. When the light intensity was reduced from 65 to 20 W m−2, the amplitude was smaller and the oscillations were damped sooner. In continuous darkness nitrate reductase activity decreased in a two step process. Three different light qualities were tested which all gave the same resu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05900.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Explants of stem pith of kale (Brassica oleraceaL. var.medullosacv. Krasa), cultured for several days on agar medium containing sucrose, accumulate starch. Application of streptomycin, 5‐fluorouracil and other inhibitors indicates that starch accumulation depends on protein synthesis on 80 S ribosomes. If explants derived from plants grown under natural long‐day conditions contained vascular tissue, including cambium, in addition to pith parenchyma, the amount of starch formed in the pith tissue increased up to seven fold when compared with explants without vascular tissue. Similar increase of starch content as caused by vascular tissue was achieved by the addition of kinetin ortrans‐zeatin (10 μ) in the presence of 5 μ indole‐3‐acetic acid or 1‐naphthaleneacetic acid. A further three‐fold increase in starch accumulation could be achieved by application of cytokinin and auxin to explants containing vascular tissue. When explants were derived from plants grown under natural short‐day conditions cytokinins and auxins had little or no effect, but vascular tissue enhanced starch formation significantly. The spreading of starch inducing stimulus from vascular tissue (probably from its meristematic region) to the pith parenchyma up to a distance of at least 20 mm was demonstrated. It was concluded that a hormone‐like factor other than cytokinin and auxin was involved in the stimulatory action of vascular tissue. The effects of this factor on protein accumulation and growth in the explants and its possible production by meristematic tissues in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb05901.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY