摘要:

The influence of seedling age at the time of inoculation on the regulation of nodule number in soybean (Glycine max[L.] Merr.) was examined in cv. Williams 82 and itshypernodulating mutant NOD1‐3. Nodulationwas evaluated on plants grown in plastic growth pouches or in vermiculite in 50‐ or 500‐ml glass containers in growth chamber studies. Seeds or seedlings were inoculated once withBradyrhizobium japonicumstrain USDA 110 (10kcells seedling−1) between 0 and 15 days after sowing at 3‐ or 5‐day intervals and were grown for 21 days after inoculation. Nodule number plant−1was similar across inoculation times in plants grown in growth pouches, but was significantly greater when inoculation was delayed and plants were grown in vermiculite in 500‐ml containers. Plant culture in vermiculite in 50‐ or 500‐ml containers confirmed the suppressive effect of restricted space for root growth on nodulation. Inoculation with 105or 109USDA 110 cells revealed that nodulation was inhibited by a high inoculum dose. There was a large increase in nodule number plant−1when plants were transferred from a restricted rooting environment (growth pouch culture) to a nonrestricted rooting environment (2‐1 hydroponic pots). Autoregulation was also examined in split‐root assemblies of plants in 500‐ml containers of vermiculite. Controls involved concurrent inoculation of both root halves at 0. 4 or 8 days after transplant. Treatments involved time‐separated inoculations of root halves with the primary and secondary inoculations being separated by 4 days. Plants were harvested at 21 days after inoculation. Williams 82 exhibited autoregulation of nodule number on the root half receiving delayed inoculation, regardless of plant age at the time of primary inoculation. Total nodule number plant−1invariably increased with later inoculation times. In contrast.NOD1 ‐ 3exhibited little, if any, autoregulation of nodule number. It was concluded that although Williams 82 exhibits autoregulation of nodule number andNODI ‐ 3does not, there was no finite limit to nodule number in either line since any delay in inoculation resulted in formation of a greater nodule number on both lines if root growth was not restricted. Nodule number in Williams 82 andNODI ‐ 3appears to be a function of infection sites (root size) at the time of inocu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06837.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Effects of jasmonic (JA) and abscisic (ABA) acid on the activities of lipases and proteases were studied in cultured embryos excised from apple seeds. JA stimulated alkaline (AlkL) and acid (AcL) lipases as well as proteases hydrolyzing casein, L‐cystine‐di‐β‐naphthylamide (CysβNa), glycyl‐glycyl‐glycine (GlyGlyGly) and native apple seed proteins. ABA inhibited AlkL and protease activities, with the exception of the hydrolysis of native proteins which was stimulated. The activity of AcL was not affected by ABA. AlkL was affected by JA and ABA also in vitro. An antagonistic interaction between JA and ABA on all studied enzyme activities. except CysβNa hydrolyzing protease, was observed. The positions of JA‐ and ABA‐controlled sites in the metabolic regulation of the removal of embryonal dormancy in apple s

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06838.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Uptake of O2by whole, detached, root systems of wheat (Triticum aestivumL. cv. Alexandria) was titrated with salicylhydroxamic acid (SHAM) in the presence and absence of cyanide. The resulting Qallplot was non‐linear indicating that SHAM was acting non‐specifically. The nature of the non‐specific effects was investigated in reverse titration experiments. Uptake of O2was titrated with KCN in the presence and absence of SHAM at 1 mMand 25 mM, which yielded Qcy1values of1, respectively. The results suggest that at 25 mM, SHAM inhibits the cytochrome pathway, but at 1 mMit stimulates an O2‐consuming process which is likely to be a peroxidase. A SHAM‐stimulated peroxidase could easily be washed from these roots. In vitro, the peroxidase was stimulated to a similar extent by low (1 mM) and high (25 mM) concentrations of SHAM. Failure to inhibit with high concentrations of SHAM distinguishes this peroxidase from those bitherto eluted from root tissue. Reverse titration experiments in the presence and absence of 1 mMSHAM indicated that there were no significant side effects of SHAM in root tips. These data are supported by the negligible peroxidase activity that was washed from this root fraction. In contrast, significant side effects occurred in vivo, and substantial peroxidase activity was measured in vitro, from sections 4–6 cm and 18–20 cm behind the seminal root apex. The greatest activity was found with the 4–6 cm section which may be associated with high rates of cell wall lignification. The implications of these results for measurements of root respiratio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06839.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Synthesis of chlorophyll was initiated in 5‐ to 6‐day‐old dark‐grown barley (Hordeum vulgare L. cv. Clipper)seedlings by exposing them to light in the presence of 1‐14C glutamic acid supplied via the roots.The plants were then returned to darkness. At the end of light treatment (T) and after 7 or 18 h dark treatment chlorophylls a and b were extracted, quantified (μgleaf1). purified by HPLC to their magnesium‐free derivatives (pheophytin a and b) and their molar radioactivities determined. After 2 h exposure to light followed by 6 h illumination in the presence of 1‐14C glutamic acid, seedlings had accumulated 4‐7 nmol chlorophyll leaf1and had incorporated between 900‐1 350 Bq (g fresh weight)1of radioactive label into the chlorophyll pool. When seedlings were transferred to darkness, label continued to be incorporated and after 18 h the radioactivity of the chlorophyll pool had increased by 300‐700 Bq (g fresh weight)1. Net chlorophyll content, however, remained constant during dark treatment. The increase in radioactivity of the chlorophyll pool in darkness represented the difference between a net increase of label incorporated into chlorophyll a and a small loss of label from chlorophyll b. The absence of measurable radioactivity in the phytol moiety of labelled chlorophyll a, extracted at the endof dark treatment, demonstrated thatincorporation of label was into the tetrapyrrole moiely of chlorophyll and not into the phytol chain. Light‐independent incorporation of 1‐14C glutamic acid into chlorophyll of greening barley seedlings transferred to darkness indicates that chlorophyll synthesis continues when light is withheld. We interpret the net gain in radioactivity of chlorophyll in darkness, in the absence of a net gain in chlorophyll content, to chlorophyll turnover i.e. to simultaneous synthesis and breakdown of chlorophyll when etiolated greening barley seedlings are

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06840.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A microprojectile based transient expression assay was used to investigate the functional conservation of gene regulatory mechanisms in the male gametophytes of an angiosperm (Nicotiana tabacum) and two gymnospermous (Picea abiesandPinus pinaster) species. The activities of two angiosperm gene promoters, which have previously shown to be either preferentially expressed in the male gametophyte (lat52) or highly expressed in both the sporophyte and male gametophyte (ActI), were analysed. The results showed that inP. abiesandP. pinaster, activity of theAct1 promoter was significantly higher than the activity of thelat52promoter, while the converse was observed inN. tabacum. Detailed analysis oflat525’promoter deletions demonstrated that although the minimal ‐67bp lat52core promoter was active at low levels in all three species, upstream regulatory elements conserved among several pollen‐expressed genes, including the PBI element, were not functional inP. abiesandP. pinaster. These results suggest that both taxa‐specific and conserved regulatory mechanisms operate to control gene expression during pollen germination and tube

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06841.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The involvement of the seed coat in low‐temperature germination of melon seeds was examined in two accessions differing in their ability to germinate at 14°C: Noy Yizre'el (a cold‐sensitive cultivar) and Persia 202 (a cold‐tolerant breeding line). Decoating resulted in full germination of Noy Yizre'el at 14°C, but splitting the coat increased germination only partially. Thus, the inhibition of Noy Yizre'el germination at 14°C is not due to physical constraint on radicle protrusion. At 25°C, seeds of both accessions submerged in water or agar germinated fully as long as the hilum aperture remained uncovered. Submerging the whole seed, or covering the hilum with lanolin, strongly depressed germination of Noy Yizre'el but not of Persia 202. Accessions differed in germination response to decreasing O2concentration, with Noy Yizre'el showing higher sensitivity to hypoxia. These differences were correlated with differences in seed coat structure as well as in embryo sensitivity to hypoxia. Intercellular spaces in the outer layer of the seed coat were evident in the more tolerant Persia 202, while in the sensitive Noy Yizre'el this layer was completely sealed. Sensitivity to hypoxia increased at 15°C as compared with 25°C, the increase being greater in Noy Yizre'el. It is proposed that the seed coat‐imposed dormancy at low temperature in Noy Yizre'el is the combined result of more restricted oxygen diffusion through the seed coat and a greater embryo sensitivity to hypoxia, rather than to physical constraints of radicle break‐through or impairmen

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06842.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Four cell wall proteins of seedling cotyledons ofProsopis chilensiswere characterized by SDS‐polyacrylamide gel electrophoresis. The molecular masses of these proteins were 180, 126, 107 and 63 kDa. All of them immuno‐crossreacted with polyclonal antibodies raised against extensin from soybean seed coats. Immuno‐dot blot analysis demonstrated that the minimum expression of cotyledonary cell wall proteins was 48 h after seed imbibition, while 24 h after wound stress the expression of these wall proteins increased four‐fold. Tissue immuno‐prints and immuno‐histochemistry showed that the proteins are expressed in the cell wall of all tissues. However, the epidermis and vascular bundles of cotyledons, hypocotyls and roots, and the living cells surrounding the wounded areas highly expressed the wall proteins. When the primary roots of the seedlings were injured by performing cuts with razor blades, the seedlings achieved a growth three times faster than control seedlings and secondary roots developed in sites close to the injuries. Immuno‐histochemistry of secondary roots revealed that the root tips and the area of the cortical tissue of the primary roots being pressed by the the emerging root tip, highly expressed the cell

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06843.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Growth of willow‐leaf mandarin (Citrus deliciosaTen.) nucellar callus cultures without embryo formation was supported on sucrose as the sole carbon source. Somatic embryogenesis was obtained by substituting galactose for sucrose at the same concentration (0.15M). A histocytological study revealed proliferation of young globular embryos during the first half of the 18‐day culture cycle, irrespective of the carbon source. However, during the second half of the cycle, further embryo development failed in cell cultures on sucrose‐containing medium. The rate of cell growth and the carbohydrate depletion of the medium were 3‐fold higher on sucrose than on galactose‐containing medium. Cell suspensions on sucrose differed by an increase in calcium, phosphorus, magnesium and potassium utilization soon after subculturing, followed by a sharp decrease. Finally, the phosphorus utilization rate per g dry weight formed was 2‐fold higher in cell cultures on galactose during the second half of the culture cycle, coinciding with further embryo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06844.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

An increase in phosphatidylcholine (PC), phosphatidyl‐ethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI) occurred during bud break induced by decapitation. Inositol‐1‐phosphate [Ins(l)P1], inositol‐1,4‐bisphosphate [Ins(1,4)P2], and inositol‐1,4,5‐triphosphate [Ins(1,4,5)P3] were found in apple buds and increased progressively following decapitation. Ins(1)P1and Ins(1,4)P2peaked 48 h after decapitation and Ins(1,4,5)P3peaked 72 h after decapitation during the metabolic transition when buds emerged from dormancy. Ins(1,4)P2and Ins(1,4,5)P3levels declined there after. The lateral buds on shoots with intact terminals and decapitated shoots treated with indole‐3‐acetic acid (IAA) in the terminals tip remained dormant and there were no significant changes in phospholipid and inositol p

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06845.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The photosynthetic contribution of a fruit to its carbon requirement throughout ontogeny and under different growing conditions was quantified in cucumber (Cucumis sativusL. cv. Corona). In addition, the effects of shading on fruit dry matter accumulation and the diurnal course of the elongation rate were studied. Fruit darkening had no photomorphogenic effect on fruit growth, while the cumulative photosynthetic contribution of a fruit to its own carbon requirement ranged from 1 to 5%. During the day there was always a net CO2efflux. The photosynthetic rate per fruit, calculated as the difference between rates of CO2exchange in light and dark, increased during fruit ontogeny, while the photosynthetic rate per unit fruit surface area declined. The latter was not dependent on fruit size. The photosynthetic activity per unit surface area of fruits was estimated to be about 20–30% as efficient as that of leaves. The rate of calculated photosynthesis was reduced by 60–65% when the photosynthetically active radiation incident on the fruit decreased from 200 to 50 μmol m−2s−1. Temperature (20–30°C) had no pronounced effect on the rate of calculated fruit photosynthesis when fruits of the same developmental stage (temperature sum) were compared. However, the relative photosynthetic contribution of a fruit to its carbon requirement increased when temperature decreased. Moreover, this contribution increased when irradiance increased or fruit growth was reduced by competing fruits. During fruit ontogeny the daily photosynthetic contribution was highest (up to 15%) in young and old fruits, with a small

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1995.tb06846.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY