Nitrogen Fixation, Assimilation and Transport During the Initial Growth Stage of Phaseolus vulgaris L

In nodulated common bean (Phaseolus vulgaris L.), there is typicallya period of N stress between 15 and 20 d after emergence (DAE),due to a lack of synchronization between the depletion of Nin the cotyledons and the beginning of N² fixation and transport.Screening trials identified some Rhizobium leguminosarum bv.phaseoli strains with which symptoms of N deficiency were notvisible (‘precocious’ strains). Cultivar Negro Argelwas then inoculated with two ‘traditional’ strains(C-05 and CIAT 727) and two ‘precocious’ strains(CNPAF 146 and CNPAF 512), and plants were harvested from 8to 30 DAE. There were no differences between the two groupsof strains in nodule dry weight or in the acetylene reductionrates between 8 and 16 DAE. However, nodules induced by the‘precocious’ strains showed earlier onset of glutaminesynthetase (GS) (EC 6.3.1.2 [EC] ) and glutamate synthase (GOGAT)(EC 1.4.1.14 [EC] ) activities, and ureide synthesis. The N concentrationin the nodules formed by ‘precocious’ strains variedfrom 4.2 to 4.5%, whereas with the ‘traditional’strains, it increased from 3.2% at 8 DAE to 65% at 18 DAE, atwhich time plants exhibited N-deficiency symptoms. By 21 DAE,GS and GOGAT activities in ‘traditional’ noduleswere increased, as well as the ureide-N-concentration in thexylem sap, nodule N content declined to 4.5% and the leavesbecame green. These results suggest that the N stress with ‘traditional’strains is not a limitation in early N² fixation activity butrather in the rates of expression of the processes of N assimilationand transport. Key words: Glutamate synthase, glutamine synthetase, nitrogen fixation, Phaseolus vulgaris, Rhizobium     

Further Observations on Fungi Inhabiting Pine Stumps

Growth-rates, both on malt agar and in stump wood, of earlystump colonizers such as Fomes annosus, Pemophora gigantea,Stereum sanguinolentum, and Leptographium lundbergii are higherthan those of later-colonizing agarics. The initial invasionof stump roots usually proceeds via the stump body by fungiwhich infect the cut surface. Although stumps may dry out appreciably shortly after felling,in later stages of decay the moisture content of the wood oftenincreases considerably. Stump decomposition is associated witha succession of decay fungi, the ‘Peniophora’, ‘Hypholoma’,and ‘Tricholoma’ stages being distinguished. Severalphycomycetes and fungi imperfecti colonize decayed, but notfresh, stump wood. P. gigantea is shown to be a vigorous competitor of F. annosusfor initial colonization of stumps: it may also replace F.annosus in stumps. Gliocladium viride and Trichoderma viridecompete with wood-rotting basidiomycetes and sometimes replacethem in very decayed wood.     

Dimorphism and Monomorphism in the Plumbaginaceae: II. Pollen and Stigmata In the Genus Limonium

A survey of pollen- and stigma-dimorphism and monomorphism inthe genus Limonium (as understood at present) reveals considerableheterogeneity which is useful for the solution of taxonomic,phylogenetic, and phytogeographic problems. Two main pollen types (A and B) and two main stigma types (coband papillate) occur in the genus. Capitate stigmata also occur. ‘Type A’ pollen has frequently been found in conjunctionwith ‘papillate’ stigmata as a secondarily monomorphic(self-compatible) combination and this must have arisen at leastfour times in the genus as well as in Armeria. ‘Type B’pollen and ‘cob’ stigmata are recorded togetherfor the first time (also as a secondarily monomorphic, self-compatiblecombination) in L. echioides. Apomixis, already discovered insubsections Densiflorae and Dissitiflorae, has been found inL. cosyrense of the subsection Steirocladae. The taxonomic and phylogenetic significance of the facts indiscussed.     

Ethylene Production by Fe-deficient Roots and its Involvement in the Regulation of Fe-deficiency Stress Responses by Strategy I Plants

Species that showed marked morphological and physiological responsesby their roots to Fe-deficiency (Strategy I plants) were comparedwith others that do not exhibit these responses (Strategy IIplants). Roots from Fe-deficient cucumber (Cucumis sativusL.‘Ashley’), tomato (Lycopersicon esculentumMill.T3238FER) and pea (Pisum sativumL. ‘Sparkle’) plantsproduced more ethylene than those of Fe-sufficient plants. Thehigher production of ethylene in Fe-deficient cucumber and peaplants occurred before Fe-deficient plants showed chlorosissymptoms and was parallel to the occurrence of Fe-deficiencystress responses. The addition of either the ethylene precursorACC, 1-aminocyclopropane-1-carboxylic acid, or the ethylenereleasing substance, Ethephon, to several Fe-sufficient StrategyI plants [cucumber, tomato, pea, sugar beet (Beta vulgarisL.),Arabidopsis(Arabidopsis thaliana(L.) Heynh ‘Columbia’), plantago(Plantago lanceolataL.)] promoted some of their Fe-deficiencystress responses: enhanced root ferric-reducing capacity andswollen root tips. By contrast, Fe-deficient roots from severalStrategy II plants [maize (Zea maysL. ‘Funo’), wheat(Triticum aestivumL. ‘Yécora’), barley (HordeumvulgareL. ‘Barbarrosa’)] did not produce more ethylenethan the Fe-sufficient ones. Furthermore, ACC had no effecton the reducing capacity of these Strategy II plants and, exceptin barley, did not promote swelling of root tips. In conclusion,results suggest that ethylene is involved in the regulationof Fe-deficiency stress responses by Strategy I plants.Copyright1999 Annals of Botany Company. Arabidopsis (Arabidopsis thaliana(L.) Heynch), barley (Hordeum vulgareL.), cucumber (Cucumis sativusL.), ethylene, iron deficiency, maize (Zea maysL.), pea (Pisum sativumL.), plantago (Plantago lanceolataL.), ferric-reducing capacity, sugar beet (Beta vulgarisL.), tomato (Lycopersicon esculentumMill.), wheat (Triticum aestivumL.).     

Narrow-leafed Lupins with Restricted Branching

Crop phenology is one of the most important characters influencingproductivity in a given environment. Narrow-leafed lupin (Lupinusangustifolius L.) is a major grain legume crop in southern Australiawith general phenological adaptation to this Mediterranean-typeenvironment. However, it is an indeterminate crop with severalassociated limitations to productivity, such as overlappingvegetative and reproductive growth, late grain filling and sometimesexcessive vegetative growth. Here we studied two novel typesof narrow-leafed lupin with restricted branching, which mightbe useful for overcoming these problems. These restricted branchinglupins arose spontaneously within a breeding population, inthe case of ‘Tallerack’, and within a farmer's cropin the case of ‘ Hurst’ and we compared them withthe ‘Merrit’, which is widely grown and has thenormal indeterminate branching habit. The morphology and developmentof the main shoot of these genotypes were similar. However,‘Hurst’ had much larger leaves. There were alsostriking differences in the lateral branches of the restrictedbranching types; they had fewer leaves than ‘Merrit’and flowered earlier. These differences were most marked in‘ Hurst’, where the upper main stem branches werereduced to a single floret in the axil of main stem leaves,and these flowers often exhibited abnormal morphology. Copyright2000 Annals of Botany Company Lupinus angustifolius L., narrow-leafed lupin, adaptation, development, morphology, branching, leaves, mutant, plastochron, phyllochron, floral initiation, flowering.     

ASYNCHRONOUS REPRODUCTIVE ACTIVITY IN THE BROADCAST SPAWNER CELLANA CAPENSIS (GMELIN, 1791) (GASTROPODA: PATELLIDAE)

Short-term fluctuations in the reproductive condition of thelimpet Cellana capensis are described. Gravimetric and histologicalanalyses of gonadal development were carried out on samplescollected at 4 day intervals over a 3 month period from theMkambati Nature Reserve, Transkei. The results indicate a distinctlack of reproductive synchrony within the population, whichapplied not only to gametogenic development per se but alsoto spawning activity. Some of the spawning events identifiedduring the study period were more marked than others, thesemay reflect a greater degree of synchronization in activity.Results presented suggest that C. capensis is probably a ‘partial’rather than a ‘complete’ spawner. The implicationsof asynchronous spawning activity for the reproductive successof broadcast spawners are also discussed. (Received 6 December 1988; accepted 15 February 1989)     

Determinate Floral Buds of Plantain (Musa AAB) as a Site of Adventitious Shoot Formation

Floral buds of the ‘False Horn’ plantain clonesMusa (AAB) ‘Harton Verde’, ‘Harton Negra’,and ‘Currare’ terminate in a large single floralstructure. The apices of these floral buds are here designatedas determinate since they have lost the ability to produce additionalfloral initials or buds. Terminal peduncle segments can be culturedin a modified Murashige and Skoog (1962) medium supplementedwith N⁶-benzyl-aminopurine (5 mg I^–1). Under these conditions,this apparent inability to yield buds can be overcome as vegetativeshoot clusters form in the axils of the bracts. Rooted plantletsare obtainable by treating shoots with naphthaleneacetic acid(1 mg I^–1) and activated charcoal (0.025%). The adventitiousorigin of the shoots has been established. Musa cultivars, plantains, floral bud, adventitious buds, tissue culture     

Developmental Genetics and Morphological Evolution of Flowering Plants, Especially Bladderworts (Utricularia): Fuzzy Arberian Morphology Complements Classical Morphology

This review compares new developmental models on flowering andother vascular plants with evolutionary hypotheses formulatedby Agnes Arber (1879–1960) and like-minded botanists.Special emphasis is laid on philosophical basics such as perspectivism,pluralism about evolutionary modelling, continuum way of thinking,and fuzzy logic. Arber's perspective is best labelled as F uzzyA rberian M orphology (FAM Approach). Its proponents (‘FAMmers’)treat structural categories (e.g. ‘roots’, ‘shoots’,‘stems’, ‘leaves’, ‘stipules’)in vascular plants as concepts with fuzzy borderlines allowingintermediates (including transitional forms, developmental mosaics).The FAM Approach complements Cla ssical Plant M orphology (ClaMApproach), which is the traditional approach in botany. ClaMproponents (‘ClaMmers’) postulate that the structuralcategories of vascular plants are regarded as concepts withclear-cut borderlines and without intermediates. However, duringthe evolution of vascular plants, the root-shoot distinctionand the stem-leaf distinction have become blurred several timesdue to developmental changes, resulting in organs with uniquecombinations of features. This happened, for example, in thebladderworts (Utricularia, Lentibulariaceae). When focusingon the ‘leaf’, the FAM Approach is identical toArber's ‘partial-shoot theory of the leaf’ and Sinha's‘leaf shoot continuum model’. A compound leaf canrepeat the developmental pathway of the whole shoot, at leastto some degree. For example, compound leaves of Chisocheton(Meliaceae)with indeterminate apical growth and three-dimensional branchingmay be seen as developmental mosaics sharing some growth processeswith whole shoots! We focus here on the FAM Approach becausethis perspective is especially promising for developmental geneticistsstudying flowering and other vascular plants. Copyright 2001Annals of Botany Company Review, body plan, developmental mosaics, leaf development, history of botany, homeosis, homeotic genes, Lentibulariaceae, morphological evolution, process morphology, stipules, Utricularia, flowering plants     

CORRECTIONS, VOLUME 29

Part 1, under the frontispiece portrait of Dr. N. B. Eales,the words ‘President 1948–1951’ should havebeen added. Page 103, line 49, for ‘Newton Collection’ read‘Norman Collection (Canon Norman)’. 185, line 37, for ‘capillaris’ read ‘capillacca’. 188, Table 1, for ‘bemoralis’. read ‘nemoralis’. 188, Table 2, for ‘Cochlicella acuta (Müll)? ventrosa(Fér.)’ read ‘Cochlicella ventrosa (Fér.)’. 191, line 24, for ‘araheo-’ read ‘archeo-’.     

The Polarity of the Cell-wall of Valonia

Further evidence is presented to show that the systems of orientationof cellulose fibrils in the cell-walls of Valonia and Dictyosphaeriamay be described by reference to two ‘poles’ uponwhich these orientation systems converge. The ‘poles’are real structural features of the wall.     

The Nitrogen Content of Plants and the Self-thinning Rule of Plant Ecology: A Test of the Core-skin Hypothesis

The ‘core-skin’ hypothesis postulates that secondarilythickened plants behave energetically as an inert ‘core’covered by an active ‘skin’, the ‘skin’being two-imensional, the ‘core’ three-dimensional.This would explain the ‘self-thinning ‘or‘–3/2’ rule of plant ecology, that is, the tendencyfor log (dry weight per plant) and log (number of plants perunit area) to progress along a straight line relationship, withslope = – 3/2’. The hypothesis was tested as follows. Plant nitrogen contentwas used as an estimate of the mass of ‘skin’ perplant, and dry weight as an estimate of the mass of the ‘core’.As plants mature the slope of the relationship between y = log(mass of nitrogen per plant) and x = log (mass of dry matterper plant) is expected to decline from an initial value of 1.0towards a final value of 0.66. The intercept of the relationshipis expected to reflect the intrinsic content of ‘skin’per unit of ‘core’. Genotypic variation in thisparameter should cause genotypic differences in the maximumattainable yield of biomass per unit area. The expectations were investigated by fitting the function y= p+qx+r exp – x to 30 sets of data on plant nitrogencontent, plant weight and time in 18 different vegetables. Simplelinear regressions of y on x were fitted to more limited setsof data on weights and nitrogen contents of mature trees. Theexpectations were, with some minor exceptions, confirmed. Nitrogen, yield, plant competition, self-thinning     

REPRODUCTIVE CYCLES OF CERASTODERMA GLAUCUM(BRUGUIERE) AND C. EDULE (L.) WITH SPECIAL REFERENCE TO THE EFFECTS OF THE 1981-82 SEVERE WINTER

Gonadal changes in two species of Cerastoderma occurring indiscrete populations in South Wales were monitored by stereologicalanalysis during the breeding seasons of 1981 and 1982. Fecundityand spawning efficiencies were determined quantitatively. Therelationship between reproductive activity and changes in meatcondition are discussed. Both species are opportunistic breeders. Their normal patternsof reproduction are similar, consisting of minimum activityin winter and peak activity during spring/early summer. Thetwo species were affected differently by the severe winter of1981–82—C. glau-cum exhibited a single, ‘epidemic’spawning and resumed gametogenesis after a 4-month resting period.C. edule adopted a ‘polycyclic’ pattern withouta resting period. Both of these unusual reproductive strategies,augmented by reduced predation resulted in heavy spatfalls. (Received 20 March 1985; revised 20 March 1985;     

Evolution of parental care in Phodopus: Conflict between adaptations for survival and adaptations for rapid reproduction

SYNOPSIS. Two species of dwarf hamsters are used to developa model of the proximate and ultimate selective forces leadingto the evolution of parental care strategies. One species, Phodopuscampbelli, has been studied extensively as a socially monogamous,biparental species; the other, P. sungorus, rears its youngwithoutmale assistance. The cold, arid habitat occupied by both species has selectedfor shape, insulation, and physiology that provide toleranceof extremely cold ambient temperatures and enhance survivalwhen water availability is limited. At the same time, the smallbody size and highly seasonal environment have selected forrapid maturation and the most compressed reproductive cycleknown in a mammal. Rapid reproduction increases water demandsfor milk production and further stresses water balance becausematernal hyperthermia demands increased evaporative heat loss.Thus, in Phodopus habitat, rapid reproduction requires heattolerance and water availability, which conflict with adaptationsfor survival. In the habitat of P. sungorus, predictable rains allow a breedingseason and females rear litters alone. In P. campbelli, wateravailability is insufficient for solitary reproduction. Instead,male presence alleviates thermoregulatory, and thus water balance,stresses on the female. The result is improved pup survivaland growth. Therefore, an ‘ultimate’ reason forbiparental care in P. campbelli is its harsh environment, anda ‘proximate’ reason is a need to reduce maternalwater demand. Results confirm that independent physiologicalconstraints, in addition to constraints on energy or time investment,can be essential selective pressures in the evolution of mammaliansocial organization and behavior.     

Predator-prey interactions between Isochrysis galbana and Oxyrrhis marina. II. Release of non-protein amines and faeces during predation of Isochrysis

During the growth of Isochrysis galbana, several non-proteinamines may be detected in the growth medium. Of these, one (termed‘TTl’) accumulates in proportion to the numbersof cells present. The concentrations of ‘TTl’, andof another (termed ‘TA’), are 3–5 times higherin cultures in which Isochrysis is predated by Oxyrrhis marina.The lowest estimates of the concentration of extracellular ‘TTl’are an order of magnitude higher than those of any protein aminoacid. Of the protein amino acids, some like glycine are utilizedduring predation while others, like histidine, accumulate inthe medium Because of the unknown N-content and reactivity ofthe non-protein amines during HPLC, it is not possible to sayif these compounds (together with other components of dissolvedorganic N) form a significant proportion of the unaccountedfor N in the system after predatory activity. During predationin the absence of detectable free ammonium (when Isochrysismay be expected to be N-deprived), particles accumulate in themedium. Most of these are <2.5 µ.m in diameter andare suggested to be remains of digested prey. There is evidenceof a reassimilation of these particles by prey-deplete Oxyrrhis.     

Fruit Position and Fruit Set Sequence in a Truss as Factors Determining Final Size of Tomato Fruits

The position of fruits in a truss and the induction sequenceof fruit set has been examined for the effects on the finalsize of parthenocarpic fruits in tomato. Fruits at two developmentalstages were examined to measure the change of d. wt and theimport of ¹⁴C leaf assimilates. The sequence of induction largely determined the import rateinto fruits of the same truss and first-induced fruits are thereforelarger within the same truss. The position of fruits in thetruss modifies the extent of this ‘primigen dominance’effect. Possible mechanisms for this dominance phenomenon arediscussed. Position, set sequence, size, fruit, Lycopersicon esculentum Mill     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

Relative Sensitivity and Tolerance of some Gladiolus Cultivars to Sulphur Dioxide

Five Gladiolus cultivars, namely ‘Aldebaran’, ‘BrightEye’, ‘Illusion’, ‘Manisha’ and‘Manmohan’, were exposed to 1 and 2 µg l^–1sulphur dioxide to test their relative-sensitivity toleranceto the pollutant Plants were fumigated experimentally for 2h daily Foliar injury symptoms were observed first in ‘Manisha’followed by ‘Aldebaran’ and ‘Illusion’at the higher dose Photosynthetic pigments and leaf extractpH were significantly decreased, particularly in ‘Manisha’and ‘Illusion’ Overall disturbances in the plantmetabolism due to SO₂ treatment led to retarded growth of plants,as evident from decreased shoot length and phytomass valuesThe order of sensitivity of the five Gladiolus cultivars toSO₂ was as follows, with the greatest first Manisha, Illusion,Aldebaran, Bright Eye, Manmohan Cultivars, Gladiolus, sensitivity, sulphur dioxide, tolerance     

A Cytochrome P450 Mediated Naringenin 3'-Hydroxylase from Sweet Orange Cell Cultures

A microsomal flavonoid 3'-hydroxylase (F3'H) catalyzing themetabolism of naringenin to eriodictyol in Citrus sinensis (L.)Osbeck cv. ‘Hamlin’ cell suspension cultures wasshown to be a cytochrome P450 enzyme. This reaction requiredO₂ and NADPH and was inhibited by CO, with partial reversalof CO-inhibition by light at 450 nm. Cytochrome P450 contentranged from 10–20 pmol (mg microsomal protein)^–1.The F3'H reaction was shown to be linear in regard to proteinconcentration between 2.5 and 25 µg of microsomal protein.The optimum pH for the reaction was 7.4–7.6 and the temperatureoptimum was between 30 and 37°C. The apparent K_m and V_maxfor naringenin were 24 µM±3.2 and 81.4±7.9pmol eriodictyol min^–1 (mg protein)^–1, respectively.The microsomal F3'H was also capable of forming dihydroquercetinfrom dihydrokaempferol (40 pmol min^–1 (mg protein)^–1)and of quercetin from kaempferol (3.25 pmol min^–1 (mgprotein^–1). Cytochrome c and ketoconazole were the bestinhibitors of WH activity followed by piperonyl butoxide anda-naphthoflavone. Light was shown to be an inducer of the F3'Halmost doubling the specific activity and increasing the microsomalcytochrome P450 content by 30% over that of dark grown cells.F3'H activity was also confirmed in microsomal preparationsof young (new flush) leaves from ‘Hamlin’ treesand flavedo of ‘Hamlin’ oranges, ‘Marsh’grapefruit, and ‘Lisbon’ lemon. No activity wasobserved in older, hardened leaves and albedo of all the fruittested. Initiation of embryogenesis in the ‘Hamlin’cell suspension cultures by switching from a sucrose mediumto a glycerol-based medium resulted in the down-regulation ofF3'H. ¹Mention of a trademark, warranty, proprietary product, or vendordoes not constitute a guarantee by the U.S. Department of Agricultureand does not imply its approval to the exclusion of other productsor vendors that may also be suitable.     

ERRATA

Effects of coupled solute and water flow in plant roots withspecial reference to Brouwer's experiment. Edwin L. Fiscus. p. 71 Abstract: Line 3 delete ‘interval’ insert‘internal’. p. 73 Materials and Methods: line 6: delete ‘diversion’ insert ‘division’ line 9 equation should read J_v=L_p P–RT(C⁰–C¹). 74 Last line of figure legend: 10^–1 should read 10^–11. 75 Line 11: delete ‘seems’ insert ‘seem’. le 1 column heading—10⁶ should read 10¹¹. 77 delete ‘...membrane in series of...’ insert ‘membranein series or...’ Delete final paragraph.     

The Effects of Salinity upon Galactosyl-Glycerol Content and Concentration of the Marine Red Alga Porphyra purpurea (Roth) C.Ag.

Changes in the major alcohol-soluble, low molecular weight carbohydratesof P. purpurea, O--D-galactopyranosyl-(1-2)-glycerol (‘floridoside’)and O--D-galactopyranosyl-(1-1)-glycerol (‘isofloridoside’),have been examined in response to salinity variation. ‘Floridoside’is shown to vary in absolute amount, increasing in hypersalineand decreasing in hyposaline media. ‘Isofloridoside’content per cell does not change in a similar manner. Responsesare almost identical under light or dark conditions, ‘floridoside’changes being complete within 24 h. Decreasing the externalwater potential using ionic and non-ionic solutes has the sameeffect upon galactosyl-glycerol content. The amount of ‘floridoside’synthesized, and degraded under hypersaline and hyposaline conditionsrespectively is shown to be insufficient to restore cell volumeto its original value. It is therefore suggested that the primaryfunction of ‘floridoside’ increases in concentratedsea-waters is that of a compatible solute, serving to protectthe cell during periods when the external salt content is increaseddramatically.