摘要:

Transcription of nitrate reductase (NR) genes is regulated by nitrate as well as a variety of other environmental and developmental factors. TwoNRgenes have previously been characterized in bean (Phaseolus vulgaris). Both genes are nitrate‐ and light‐inducible and their mRNA expression level displays a circadian rhythm. The two genes,NR1andNR2, show differences in developmental and tissue‐specific expression. In order to deliniate elements in theNR1andNR2promoters that are involved in these expression patterns, eight 5′deleted versions of theNR1promoter and one fragment of theNR2promoter were cloned in front of the GUS reporter gene and transformed into tobacco. Approximately 50% of the regenerated transformants expressed detectable levels of GUS activity. For the eightNR1promoter deletion constructs, differences in promoter strength were observed indicating both positive and negative elements in the promoter. For both theNR1and theNR2promoter‐GUS constructs no significant nitrate regulation could be detected in the transgenic plants. A possible explanation for this is that elements needed for proper nitrate regulation of theNR1andNR2genes are located outside the analysed 3 500 bp and 1 400 bp promoter regions, respectively. A diurnal rhythm regulation similar to that seen for the endogenous nitrate reductase in bean plants, could be found for the GUS mRNA expression in several of the transformants containing theNR1andNR2promoter‐GUS

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00444.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Auxin‐induced elongation of com coleoptiles is accompanied by cell wall acidification, which depends upon H+‐pump activity. We tested the hypothesis that phospholipase A and a protein kinase are involved in the pathway of auxin signal transduction leading to H+secretion, and elongation of corn coleoptiles. Initially, the pH of the bath solution at 50–100 μm from the surface of a coleoptile segment (pHo) ranged between 4.8 and 6.6 when measured with an H+‐sensitive microelectrode. Twenty or 50 μMlysophosphatidylcholine, 50 μMlinolenic acid or 50 μMarachidonic acid induced a decline in pHoby 0.3 to 2.1 units. The effect was blocked by 1 mMvanadate, suggesting that lysophosphatidylcholine or linolenic acid induced acidification of the apoplast by activating the H+‐pump. Lysophosphatidylcholine and linolenic acid also accelerated the elongation rate of the coleoptiles. While linolenic acid and arachidonic acid, highly unsaturated fatty acids, promoted pHodecrease and coleoptile elongation, linoleic acid, oleic acid, and stearic acid, fatty acids with a lesser extent of unsaturation, had no such effects. The effects of lysophosphatidylcholine, linolenic acid, and arachidonic acid on H+secretion were not additive to that of indoleacetic acid (IAA), suggesting that lysophospholipids, fatty acids and auxin use similar pathways for the activation of the H+‐pump. The phospholipase A2inhibitors, aristolochic acid and manoalide, inhibited the IAA‐induced pHodecrease and coleoptile elongation. The general protein kinase inhibitors, H‐7 or staurosporine, blocked the IAA‐ or lysophosphatidylcholine‐induced decrease in pHo. H‐7 also inhibited the coleoptile elongation induced by IAA or lysophosphatidylcholine. These results support the hypothesis that phospholipase A is activated by auxin, and that the products of the enzyme, lysophospholipids and fatty acids, induce acidification of the apoplast by activating the H+‐pump through a mechanism involving a protein kinase, which in turn promote

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00445.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Cloned catalase probes from barley (Hordeum vulgareL.) and maize (Zea maysL.) were used to examine catalase gene expression in greened and etiolated leaves of several barley lines. Etiolated leaves had greater levels of an mRNA detected by barleyCat1, compared with greened leaves, in all lines. In contrast, aCat2‐like mRNA (homologous toCat2of maize) was induced by light and accumulated to high levels in greened leaves, compared to the negligible levels detected in etiolated leaves. This suggests that barley contains light‐inducible and light‐repressible catalase genes. In the catalase‐deficient barley mutant RPr 79/4, no hybridization signal was detected when RNA from greened or etiolated leaves was probed with maizeCat2, indicating that this mutant is deficient for the light‐inducedCatmRNA. In etiolated seedlings of both RPr 79/4 and its motherline, the level of theCat1mRNA increased coordinately with a steady increase in catalase activity. Even though the mutant RPr 79/4 was able to grow to maturity in normal air, it sustained chlorosis and significant head sterility, probably due to the lack of a light‐inducible catalase. Although the mutant RPr 79/4 is not completely lacking catalase (EC 1.11.1.6), the loss of the CAT‐1 isozyme is evidently harmful. This observation underscores the protective role of catala

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00446.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Cucumber (Cucumis sativusL. cv. Poinsett 76) seeds were chilled at 2.5°C in a study of the chilling sensitivity and recovery of radicle tissue. The effect of chilling on radicle growth and the production of carbon dioxide and ethylene was measured. Chilling sensitivity of radicles increased as they grew from 1 to 7 mm in length. The length, not the age of the radicles, determined the level of chilling sensitivity. Apical tissue was most sensitive to chilling and slowest to recover from chilling, followed by subapical and basal tissue. Our data demonstrate that the chilling sensitivity of young seedling radicles differs along their length and that the rapid chilling‐induced inhibition of elongation is probably due to an inability of meristematic cells to remain viable and active when chill

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00447.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

During a slow desiccation in photosynthetically fully active leaves of the poikilochlorophyllous desiccation‐tolerant (PDT) monocotyledonXerophyta scabrida(Pax) Th. Dur. et Schinz (Velloziaceae), thylakoid activity, CO2assimilation and respiration decline and chlorophylls and carotenoids are successively broken down. The initially slow rate of leaf water loss is related to the large reduction in leaf area which is reflected in the decrease of specific leaf area. Chlorophylls are broken down faster than carotenoids. The ratio of the variable chlorophyll fluorescence, an indicator of photosynthetic activity (Rfd690‐values), shows that the functionality of thylakoids and chlorophylls is successively lost during desiccation. The decline in net CO2assimilation in desiccating leaves is largely caused by stomatal closure. The complete cessation of CO2assimilation, however, is due to the breakdown of chlorophylls and thylakoids. Respiration continued during desiccation and remained active far below ‐3.2 MPa leaf water potential. The differences during desiccation of the photosynthetic apparatus between poikilochlorophyllous and homoiochlorophyllous desiccation‐tolerant plants are di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00448.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Stomatal conductance in improved Pima cotton cultivars (Gossypium barbadense) has been previously shown to be positively associated with heat resistance and yield potential. In the present study we determined the mode of inheritance of stomatal conductance in crosses of sixG. barbadenseparents varying in origin, degree of agronomic development and stomatal conductance. Parents included a primitive tropical cotton (B368), two obsolete cultivars (St Vincent V135, Pima 32), one modern commercial line (Pima S‐6) and two elite genotypes of the Pima germplasm (P70, P73). These lines showed distinct differences in stomatal conductance, under greenhouse and field conditions. The primitive B368 had the lowest conductance, and the elite lines the highest. Generation means analysis was used to quantify genetic effects in the crosses P70 × St Vincent V135, Pima S‐6 × B368, Pima S‐6 × Pima 32, P73 × Pima 32 and P73 × Pima S‐6. Best‐fit models of the inheritance of stomatal conductance varied in complexity from a simple additive‐dominance model in the cross P70 × St. Vincent V135 to models displaying digenic epistatic interactions in the remaining crosses. Significant additive mean effects for stomatal conductance were detected in all crosses. Dominance mean effects were significant in the crosses P73 × Pima 32 and P73 × Pima S‐6. Broadsense heritability estimates of stomatal conductance were relatively low (0.16–0.44) in all crosses except Pima S‐6 × B368 (0.74). Results also show that the mode of inheritance of stomatal conductance is multigenic, and may have maternal as well as nuclear components. Recouping higher stomatal conductance levels from genetically wider crosses appears feasible and could proceed at a moderate rate. Fixing higher levels of stomatal conductance in populations from crosses of elite germplasm may be more difficult because of the presence of dominant mean effects and dige

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00449.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Exposure to osmotic stress reduces leaf area and protoplast volume while decreasing photosynthesis. But the measurement of protoplast volume is tedious, while rapid determinations of leaf area in the field are difficult. We evaluated the quantitative relationship between the extent of decrease in area of detached leaf discs or the volume of protoplast of pea (Pisum sativum) and reduction in their photosynthetic capacity under osmotic stress. Osmotic stress was induced by increasing sorbitol concentration in the surrounding medium of the leaf discs from zero to 1.0M(‐3.1 MPa), and in case of protoplasts from 0.4M(‐1.3 MPa, isotonicity) to 1.0M(‐3.1 MPa, hypertonicity). There was a high degree of positive correlation between the extent of reduction in the area of detached leaf discs or the volume of protoplasts (indicated by diameter or absorption at 440 nm) and the decrease in photosynthesis. The correlation coefficients between inhibition of photosynthesis and the decrease in leaf disc area or protoplast volume were 0.96 and 0.99, respectively. We therefore suggest that the decrease in absorbance at 440 nm (corrected for turbidity at 750 nm) can be used as a simple measure to predict the inhibition due to osmotic stress of photosynthesis in mesophyll protoplasts. Similarly, the reduction in area of detached leaf discs could also be a very simple and useful criterion to assess osmotic tolerance of photosynt

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00450.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00451.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

We examined the functional relationship between chlorophyll concentrations and light spectral absorption in 16 species of woody, vine and herbaceous plants in northern Japan. Leaves of each species from under forest shade and in more open sites were measured for chlorophyll, specific leaf area (SLA) and spectral absorption. In all species, SLA increased and the Chla:bratio declined in shade‐ vs open‐grown leaves indicating an adaptive adjustment to forest shade in these leaf characters. However, the expected increase in the ratio of 680 to 700 nm absorption in shade leaves did not occur in all species. Light absorption at 680 relative to 700 nm was lower in the shade leaves ofAcer japonicum. Kalopanax pictus, Panax japonicusandPetasites japonicuseven with a reduced Chla:b, a commonly accepted indicator of shade adaptation. Therefore, spectral measurements in these species failed to support Chl concentrations that were expected to confer an improvement in the absorption of red light (700 nm) in the forest shade. Compared with other species, the absorption pattern of these four ‘non‐conforming’ species is associated with a higher ratio of shade:open leaves in reflectance spectra in the 600–750 nm range. This suggests an increased reflectance in shade leaves caused by changes in leaf surface properties which are not immediately apparent. We conclude that adaptive spectral absorption cannot always be inferred from changes in specific leaf area and chlorophyllaandbc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00452.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Changes in polyamine biosynthesis in relation to submergence‐enhanced shoot elongation were determined in shoots ofScirpus mucronatusL. Under submergence, the levels of free putrescine and the activities of arginine decarboxylase (ADC, EC 4.1.1.19) and ornithine decarboxylase (ODC, EC 4.1.1.17) increased, but the levels of free spermidine and spermine and the activity ofS‐adenosylmethionine decarboxylase (SAMDC, EC 4.1.1.50) decreased. The increases in free putrescine and shoot elongation in submerged shoots diminished from the base to the apex. The increase in free putrescine in submerged shoots was coincident with the increase in shoot length. The submergence‐induced increases in free putrescine and shoot elongation were inhibited by both 5 μMa‐difluoromethylarginine and 5 μMa‐difluoromethylornithine, and the inhibitory effects were reversed by 50 μMputrescine. These overall results indicate that ADC‐ and ODC‐mediated putrescine synthesis is essential for the elongation ofScirpusshoots grown u

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb00453.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY