摘要:

Pith segments isolated from haploid and diploid Nicotiana tabacum cv. IAC‐70 plants from five different heights in the stem, were cultured in vitro on MS‐62 medium supplied with 0.5 mg/l IAA and 0.02 mg/l kinetin. Pith tissues of haploid plants showed greater growth potential than those of diploids; peroxidase activity was higher in the calluses of diploid tissues whereas protein content was higher in those of haploids. After three subcultures the growth pattern was inversed, as were the results for peroxidase activity and protein content. After the onset of culture, peroxidase activity in haploid explants dropped sharply, reaching values lower than in diploid tissues 40 d later, but after three subcultures these values were higher than those for diploid calluses. The results are discussed from the viewpoint of a possible relationship between greater polyploidization in haploid tissues on the one hand and growth decrease and peroxidase activity increase on the ot

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02691.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Photosynthetically active radiation (PhAR) is apparently the environmental factor having the greatest influence on leaf thickness forPlectranthus parviflorusHenckel (Labiatae). A four‐fold increase in leaf thickness from 280 to 1170 μm occurred as the PhAR was raised from 1.3 to 32.5 mol m−2day−1. Compared to a constant PhAR of 2.5 mol m−2day−1, a PhAR of 32.5 mol m−2day−1for one week during the first week (with return to 2.5 mol m−2day−1during the second and third weeks) led to an increase in final leaf thickness by 323 μm (to 802 μm). When increased PhAR was applied during the second week the increase in final thickness over the control was 217 μm, and when increased PhAR was applied during the third week it was 99 μm. However, leaf thickness was not simply responding to total daily PhAR, since a leaf 450 μm thick could occur at a low instantaneous PhAR for a long daytime (total daily PhAR of 1.5 mol m−2day−1) and at a high PhAR for a short daytime (4.5 mol m−2day−1). Total daily CO2uptake (net photosynthesis) was approximately the same in the two cases, suggesting that this is an important factor underlying the differences in leaf thickness. Leaf thickness is physiologically important, since thicker leaves tend to have greater mesophyll surface area per unit leaf area (Ames/A) and he

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02692.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The form of nickel in leaves of Iberian subspecies ofAlyssum serpyllifoliumDesv. was investigated. Subsp.lusitanicumT. R. Dudley and P. Silva (from N.E. Portugal) and subsp.malacitanumRivas Goday (from Southern Spain) were hyperaccumulators of nickel (>1000 μg/g Ni) whereas their non‐accumulating precursor (subsp.serpyllifolium) was not. Nickel existed mainly as a water‐soluble polar complex in the vacuoles. Small concentrations of nickel did however exist in cell fractions, particularly in the mitochondria where enzyme systems are located. Gas‐liquid chromatography on the purified nickel complexes showed that this element is associated principally with malic and malonic acids which are present in high concentrations in the hyperaccumulators but not in subsp.serpyllifolium. It is suggested that production of malic acid is a mechanism whereby hyperaccumulators can tolerate unfavourable edaphic factors such as nickel‐rich soils. Presence of nickel in the mitochondria can presumably block the citric acid cycle by deactivating malic dehydrogenase leading to build‐up of malic acid in the vacuoles which could then absorb excess nickel by a complexing reaction and lead to its diffusion back into the vacuoles from the mitochondria, hence unblocking the citric acid cycle. It is postulated that the chemical evidence suggests that the two hyperaccumulators are not conspecific and that subsp.malacitanumshould be promoted to full spe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02693.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Trifolium subterraneum(cv. Dinninup) responds to enriched atmospheric CO2in a manner similar to that described by Madsen (1968 and 1976) for tomato. In immature leaves, the total chlorophyll content per unit dry weight and the chlorophyll a:b ratio are significantly lower in plants grown at 0.10 vol% CO2. Although fully expanded mature leaves partially overcome the deficit in chlorophyll content, the chlorophyll a:b ratio remains substantially lower in these high CO2grown plants. The large amount of starch accumulated as irregularly shaped grains appears to disrupt normal chloroplast structure in clover plants grown in enriched atmospheric CO2. These results indicate the chlorotic appearance of leaves from high CO2grown clover plants is due to a decrease in chlorophyll content per dry weight possibly resulting from large starch grains and starch accumulation altering normal chloroplast structure and function.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02694.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The photosynthetic pigment contents and the chlorophyll fluorescence induction in Norway spruce [Picea abies(L.) Karst.] needles were monitored at 3 h intervals over a 10 day period. This covered 6 days of high insolation, one day of low insolation, followed by three more days of high insolation. During the first six days only small changes in mean pigment contents were observed but we interpret them as suggesting a daily rhythm in total chlorophyll content with two maxima and minima. The day of low insolation was paralleled by larger pigment changes, mostly an increase in chlorophyllbalong with a decrease in carotenoid content. With the resumption of high insolation, pigments gradually return to their previous levels. During the entire period chlorophyllafluorescence induction remained relatively constant. These short‐term responses may reflect features of thylakoid organization in relation to pigment content and suggest possible long‐term adaptive mechanisms in non deciduous conif

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02695.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

One‐ and two‐“year”‐old seedlings ofPinus silvestrisL., from which the buds had been removed, were studied for five weeks during the second and third growth period, respectively. Intact seedlings were used as controls. The seedlings were cultivated under controlled conditions in a climate chamber. The growth of the seedlings was determined and the one‐“year”‐old needles assayed for changes in net photosynthesis and ribulose bisphosphate carboxylase activity and in the levels of protein, Kjeldahl nitrogen, chlorophyll and starch.In the control the carboxylase activity and the content of protein, Kjeldahl nitrogen and starch in the needles increased in the beginning of the “summer” and decreased during the shoot growth period. The starch content was higher after bud removal (decapitation), since the carbohydrate could not be utilized for the growth of the new shoot. Decapitation did not affect the growth rate of the roots.The content of Kjeldahl nitrogen and total and soluble protein in the needles was higher in the decapitated seedlings during the period of shoot elongation in the control. Total nitrogen, but not protein, reached high levels, indicating accumulation of non‐protein compounds. The general course of the chlorophyll pattern was not affected. Higher ribulose bisphosphate carboxylase activity than in the control was observed in the later part of the experimental periods. The higher levels of protein and nitrogen as well as of carboxylase activity after decapitation support the interpretation that soluble protein, including the carboxylase, and possibly other nitrogen compounds in the older needles are used for growth of the shoot. The loss of protein and nitrogen and of carboxylase activity in the control did not seem to be due to mineral deficiency in the substrate.Despite higher levels of carboxylase activity and similar chlorophyll concentrations, light‐saturated net photosynthesis was lower after decapitation. The ratio between photosynthesis and photores

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02696.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

When whole plants were exposed to14CO2, almost the same amount of radioactivity was taken up initially by each leaf regardless of its position on the stem and of the presence of beans at that node. Thus, although developing beans are a powerful sink for assimilated carbon, they do not increase the CO2uptake by adjoining leaves.The distribution of labelled assimilates 6 hours after feeding14CO2to a single leaf for 1 hour varied with both the position of the treated leaf and the stage of development of the plant. Before any flowers were set most of the radioactivity from all expanded leaves moved downwards to the roots and the stem below the treated leaf (lower stem). Later, during pod‐fill, the upper leaves maintained this supply to the roots and lower stem, whilst most of the carbon translocated from the lower and mid‐stem leaves went to the beans. However, we found no exclusive relationship between a leaf and the supply to beans developing on the same node.The amount of radioactivity moving out of a source leaf at a fruiting node increased over successive samplings up to 48 h; the pattern of distribution of the14CO2however remained virtually unchan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02697.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Thylakoids isolated from spinach leaves (Spinacia oleraceaL. cvs. Monatol and Montako) were exposed to supraoptimal temperatures that inactivated their photochemical reactions. Membrane injury was accompanied by release of a small amount of membrane proteins. When sucrose was present during high‐temperature treatment, thylakoids were partially protected and release of membrane proteins was less pronounced than in the absence of sugar. From thylakoids, which were isolated from heat‐damaged spinach leaves, less protein was released when heated again after the isolation procedure, indicating that protein release also takes place during heat inactivationin vivo. Sodium dodecyl sulfate gel electropherograms of thylakoids demonstrated that heat inactivation of the lamellae was not accompanied by significant changes in the pattern of the proteins, which remained in the membranes. The same was found when thylakoids were solubilized with Triton X‐100 before and after heat damage. It is suggested that the protein release that occurs during heat treatment is a consequence of irreversible alterations in the membrane structure; these changes may be responsible for thermal damage of chloroplast memb

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02698.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The effect of various experimental parameters upon the frequency of callus formation from cultured anthers ofOryza sativahas been investigated. Although certain medium components were found to be critical to callus formation, the concentration of these components had little effect upon the frequency of callus formation. The degree to which the callus formation frequency was influenced by cold pretreatment of the flowers was variable. Even though plants were grown under uniform conditions and flowers containing pollen in the microspore stage of development were selected for dissection, the frequency of callus formation varied nonrandomly between flowers. In experiments with populations of flowers in a physiological and developmental state favorable to callus formation 35% of plated anthers produced callus and at least 60% of these calluses gave rise to green plants.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02699.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Evolution of the ploidy in four strains ofNicotiana tabacumev. P 19 was studied by cytophotometry after transformation of the cultured tissues into protoplast suspensions.The limits of these variations were analysed numerically and statistically. The method used is capable of wide application. It can be used to predict the evolution of the average ploidy level of a strain maintained on a given medium if the average ploidy level of the explant is known. Comparison is made relative to a standard of known ploidy (diploid protoplasts). Increase of the average ploidy level is faster when the explant is mainly diploid (leaf parenchyma) than when it is composed of more heterogeneous tissues as regards ploidy (shoot tip). The appearance of a random drift depends on the composition of the culture medium: it is immediate in one medium (MS2), but is preceded by a phase of relative stability in another medium (MS1) which is richer in kinetin.While the results presented specifically concern the strains cultured on media MS1and MS2, the statistical method employed is applicable to cultures of any species for which one can experimentally justify a linear regression analysis.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb02700.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY