Irregular Heartwood Formation in Maritime Pine (Pinus pinaster Ait):Consequences for Biomechanical and Hydraulic Tree Functioning

As the proportion of sapwood (SW) transformed into heartwood(HW) is irregular both radially and longitudinally in trunksof Maritime pine (Pinus pinaster Ait.), it has been suggestedthat HW formation is a developmental process, regulated internallywithin the tree. In trees where stem growth is eccentric dueto stem lean or wind action, the number of annual growth ringsof SW transformed into HW is greater on the compressed sideof the tree. To determine the contribution to bending stiffness,if any, of this prematurely formed HW, four point bending testswere carried out on fresh HW and SW samples taken from the samegrowth ring, or neighbouring growth rings, at different cross-sectionalpositions at a height of 2 m from six 52-year-old Maritime pines.The mean (±s.e.) modulus of elasticity (E) was 7.6 ±0.3 GPa (longitudinal direction) for all samples. No significantdifferences in E were found between HW and SW; thus HW doesnot play a significant mechanical role in bending stiffness.To test a second hypothesis that early HW formation on the compressedside of trees may maintain a constant, optimal volume of SWaround the tree, the Pipe Model Theory was applied to 12 52-year-oldleaning Maritime pines (angle of lean varied from 0–22°).The surface area (S) of the SW was determined at different heightsup the trunk and correlated with crown surface area (S_crown).Regressions between S_SWandS_crown were highly significant, therebysupporting the theory that HW formation and extension is controlledinternally in Maritime pine. HW formation in Maritime pine thenserves to maintain an optimal proportion of functional SW whichis an important criterion for survival in a species often subjectedto severe drought for long periods. Copyright 2001 Annals ofBotany Company Heartwood, sapwood, bending test, Pipe Model Theory, Pinus pinaster     

Stem Diameter Growth of Scots Pine Trees after Increased Mechanical Load in the Crown during Dormancy and (or) Growth

A field experiment with a 2 x2 factorial block design (W_xS_x)was conducted in northern Sweden where the mechanical loadsin the crowns of sixteen 2.5m high Scots pine (Pinus sylvestrisL.)trees were increased during one winter (W₁, dormant period)and (or) summer (S₁, growth period). Trees treated were loadedwith five 2kg bags hung over mid-crown branches close to thestem, i.e. 10kg per tree. After treatment, all trees were leftto grow untreated for one additional year. Trees were then cutat ground level and annual ring widths for the last 5 yearswere measured on stem discs taken at 1, 5, 10, 15, 20, 30 and50% of tree height. Differences between treatments were analysedwith two-way factorial ANOVA. Accumulated treatment responsewas positive for winter loading (W₁S_x) at all levels, and statisticallysignificant at 1, 15 and 20% of tree height. Summer loading(W_xS₁) had positive effects at the lowest and middle parts ofthe stem, and negative in between. No statistically significanttwo-way interaction (W xS) was observed. Results support thehypothesis that Scots pine trees can retain information aboutmechanical forces acting on their stems during winter, and respondto this during the following growth period. The results alsosuggest that stem form of trees in boreal forests may be stronglyaffected by winter conditions. Stem form; mechanical perturbation; Scots pine; Pinus sylvestris; dendrometer; diameter; growth; dormancy; thigmomorphogenesis; wind; sway     

Crown Spread Patterns for Five Deciduous Broad-leaved Woody Species: Ecological Significance of the Retention Patterns of Larger Branches

Patterns of crown spread and branch retention of two shade-intolerantspecies (Betula platyphyllaandB. maximowicziana) were comparedwith three more tolerant species (Quercus mongolica,Acer sieboldianumandMagnoliaobovata). Branching height (height of the lowest living branch)rose more rapidly with age for the twoBetulaspecies than forthe shade tolerant species. Branching heights ofA. sieboldianumandM.obovatawere similar, irrespective of tree height and age, andlarger trees tended to produce wider crowns than theBetulaspecieswhen trees of similar height were compared. In all species,the branch basal area (cross-sectional area of a branch at itsbase) and the leaf area per branch generally increased as thebranch position on a stem became lower. Therefore, retaininglarger branches contributed significantly to the support ofa larger leaf area per tree. The number of larger branches (branchbasal area >80 cm²) for bothBetulaspecies was significantlysmaller than that of the shade tolerant species. The branchretention pattern ofBetulaspecies was probably a consequenceof intolerance of the leaves to shade. The decline ofBetulaspecieswith forest succession is likely to occur through their inabilityto retain branches with a large base area in closed forests.Copyright1997 Annals of Botany Company Shade tolerance; crown spread; branch retention; branch size; broad-leaved woody species; leaf area index per tree     

The Effect of Number of Shoots on the Quantity and Distribution of Increment in Young Apple-trees: With three Figures in the Text

It is shown that the shoots of a young tree act additively ratherthan competitively, that is, each extra shoot produces a definiteextra increment in total weight, not that a constant incrementis divided among the shoots of the young tree. One-year apple-trees of 3 varieties were rigorously selectedfor size and weight, and in the spring disbudded to 1, 2, 3,or n, the natural number of shoots per plant. The treatmentswere applied in the 1st or 2nd year after planting and the incrementduring the treatment year was determined. Provided not morethan a few secondary shoots were produced on the current shoots,each additional primary shoot produced an increase in weight.In one variety plants with 1 primary shoot produced many secondariesand these plants were heavier than those with 2 primaries. The largest shoot was not greatly affected in size by the presenceof other shoots except in the variety which produced secondaryshoots readily. These were most abundant on plants with 1 primaryshoot, fewer on plants with 2, and almost negligible on plantswith 3 and n shoots. Treatment and varietal effects on the percentage distributionof increment as leaves, new stem, old-stem increment, and root,were small. The percentage of leaves in the 2nd year was abouthalf what it was in the 1st year; the percentage of root wasnearly the same in both years.     

Comparative Growth Behaviour and Leaf Nutrient Status of Native Trees Planted on Mine Spoil With and Without Nutrient Amendment

The effect of nutrient amendment on growth of nine indigenoustree species planted on coal mine spoil was studied. Greatergrowth in fertilized plots was accompanied by greater foliarN and P concentrations in all species. The response to fertilizationvaried among species and was greater in non-leguminous thanin leguminous species. Furthermore, leguminous species exhibitedhigher growth rates compared to non-leguminous species. Thelog-transformed height-diameter relationships were significantfor all tree species and treatments. Acacia catechu, Dalbergiasissoo, Gmelina arborea and Azadirachta indica fitted the elasticsimilarity model of tree growth; whereas Pongamia pinnata andPhyllanthus emblica followed the constant stress model. Tectonagrandis was the only species which fitted the geometric similaritymodel. In Albizia lebbeck and Terminalia bellirica, the b -values(the gradients of the log-transformed height to diameter relationships)were considerably lower (<0.5), and these two species didnot fit any model of tree growth. In several cases, the b -valueswere considerably influenced by nutrient amendment. The log-transformedcrown mass and trunk mass relationships were significant forall treatments and species. The slope of the crown mass:trunkmass relationship was near unity in A. indica, D. sissoo, G.arborea, P. emblica, P. pinnata, T. grandis, and T. bellirica.However, in A. catechu and A. lebbeck, this slope was well belowunity suggesting a greater allocation to non-photosynthetictissue. Fertilizer amendment resulted in a heavier crown relativeto trunk in A. indica, T. grandis and T. bellirica. Copyright2001 Annals of Botany Company Diameter increment, fertilizer application, foliar N, foliar P, height increment, tree growth, volume increment     

Growth Analysis of Perennial Plants: The Relative Production Rate and its Yield Components

A new formulation for plant growth analysis, called the relativeproduction rate, is proposed for use in the study of perennialplants. The new measure and its yield components are similarto current growth analysis, but use the annual increment ofgrowth, rather than total accumulated growth, as the basis forassessing performance. The relative production rate removesaccumulated past growth of the perennating structure, a majordeterminant of relative growth rate, and acts independentlyof tree size as a measure of the vigour of growth. The multiplicativeyield components of this relative production rate also providebetter insight into the current morphological and physiologicalfeatures of the tree than the standard growth analysis formulations.Examples are given using Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) and red pine (Pinus resinosa Ait.) plantationsto illustrate the methodology proposed. Pseudotsuga menziesii (Mirb.) Franco, Pinus resinosa Ait., Douglas-fir, red pine, growth analysis, relative production rate, tree development, competition     

Two Geometrical Models of Branching of Botanical Trees

A botanical tree may be regarded as a system of axes which developby repeated bifurcation. A complicated tree can be describedby a few parameters of bifurcation which determine the geometryof the bifurcation process. A bifurcation model (H-model) haspreviously been proposed and shown to be useful for comparisonwith trees which have branch complexes which approach a horizontalplane (e.g. Terminalia). Another bifurcation model (P-model)is now proposed which is appropriate to branching systems inwhich successive branch planes are perpendicular to each other(e.g. Cameraria and Tabernaemontana of the Apocynaceae). Bymodification of the P-model to take into account a geotropiceffect, a more realistic branching model for one kind of treespecies is produced. The relationship among these geometricalmodels of branching is discussed and illustrated with computersimulations. computer simulations, tree crown geometry, branching patterns, bifurcation models, Terminalia, Cameraria latifolia, Tabernaemontana, sp     

Stem Growth and Epicormic Branch Formation in Understorey Beech Trees (Fagus sylvatica L.)

A study of the formation of epicormic branches on suppressedbeech trees revealed developmental sequences that had not hithertobeen studied in depth. By combining architectural analysis andanatomy, it was possible to trace the history of the plant andthus fully understand the ontogenesis of the individuals studied.The main sequences observed were: (1) the formation of moribundtrees that were gradually covered in epicormic branches fromthe base of the stem to the crown following gradual forest closure;(2) the formation of this new crown of epicormic branches wascombined with a very sharp reduction in stem cambial activity(partial rings, if any) and modifications to the ligneous sections;and (3) resumed girth increment following the establishmentof epicormic branches. After describing in detail the methodsand individual variation, we highlight the spatial and temporalpatterns of the phenomena observed. Lastly, we put forward functionalhypotheses with a view to setting these results against a backgroundof forest tree ontogenesis in general. Copyright 2001 Annalsof Botany Company Fagus sylvatica L., beech, architecture, epicormic shoot, anatomy, growth, annual wood ring, missing ring     

Stem hydraulic capacitance decreases with drought stress: implications for modelling tree hydraulics in the Mediterranean oak Quercus ilex

Hydraulic modelling is a primary tool to predict plant performance in future drier scenarios. However, as most tree models are validated under non‐stress conditions, they may fail when water becomes limiting. To simulate tree hydraulic functioning under moist and dry conditions, the current version of a water flow and storage mechanistic model was further developed by implementing equations that describe variation in xylem hydraulic resistance (R_X) and stem hydraulic capacitance (C_S) with predawn water potential (Ψ_PD). The model was applied in a Mediterranean forest experiencing intense summer drought, where six Quercus ilex trees were instrumented to monitor stem diameter variations and sap flow, concurrently with measurements of predawn and midday leaf water potential. Best model performance was observed when C_S was allowed to decrease with decreasing Ψ_PD. Hydraulic capacitance decreased from 62 to 25 kg m^?3 MPa^?1 across the growing season. In parallel, tree transpiration decreased to a greater extent than the capacitive water release and the contribution of stored water to transpiration increased from 2.0 to 5.1%. Our results demonstrate the importance of stored water and seasonality in C_S for tree hydraulic functioning, and they suggest that C_S should be considered to predict the drought response of trees with models.     

Internodal Extension in the First Trifoliate Leaf Axillary Bud of Phaseolus vulgaris L. following Shoot Decapitation

Phaseolus vulgaris L. decapitated at the third internode showedaccelerated growth of the uppermost axillary bud remaining onthe stem (the first trifoliate axillary bud) after a lag periodof 3–5 h Much of the initial growth increment could beattributed to cell expansion Phaseolus vulgaris L, dwarf bean, correlative inhibition, cell expansion     

Molecular Cloning of Plant Spermidine Synthases

Four cDNAs for spermidine synthase (SPDS), which converts thediamine putrescine to the higher polyamine spermidine usingdecarboxylated S-adenosylmethionine as the co-factor, were isolatedfrom Nicotiana sylvestris, Hyoscyamus niger, and Arabidopsisthaliana. When the N. sylvestris SPDS cDNA was expressed ina SPDS-deficient E. coli mutant, the recombinant protein showedhigh SPDS activity, but did not have any spermine synthase activity.The plant SPDSs have molecular masses of about 34 kDa, possessthe co-factor binding motifs which have been proposed for S-adenosylmethionine,and are more homologous in amino acid sequence to tobacco putrescineN-methyltransferase (PMT) than to SPDSs from mammals and E.coli. The SPDS gene is expressed in root, stem, and leaf inN. sylvestris, whereas the PMT gene is expressed only in root.The potential evolution of plant SPDS and PMT, and their evolutionaryrelationships with animal SPDS are discussed. (Received September 3, 1997; Accepted November 5, 1997)     

A Mechanistic Analysis of Self-thinning in Terms of the Carbon Balance of Trees

The self-thinning behavior of a monoculture forest is examinedfrom a mechanistic viewpoint, in terms of the carbon balanceof trees at the stand level. Two approaches are described: thefirst is based on simple assumptions concerning the balancebetween growth, photosynthesis and respiration; the second usesthe process-based I.T.E. EDINBURGH FOREST model, extended toinclude tree birth and death, to examined the assumptions ofthe first approach at a more mechanistic level and to interpretthe observed variation in the responses to shading and soilfertility in terms of a single model. The first approach leads to a power law relation m n ^-1/y betweenmean biomass per tree (m) and the number of trees per unit groundarea (n), where y is the exponent characterising the rate atwhich respiration (r) scales with biomass (i.e. r m^y). Forvalues of y less than 1, m and n are predicted to increase anddecrease, respectively, as powers of time (t) such that thebiomass per unit ground area (M) increases linearly with t forany value of y. When y equals 1, m and n vary exponentiallywith t and M remains constant. When r is assumed to be proportional to stem cambium surfacearea, the value of y is shown to lie in the range 0·5to 1 depending on the rate of stem taper. This leads to slopeson a log m vs. log n self-thinning plot in range -1 to -2 andtypically around -1·5 for rates of taper based on mechanicalrequirements. For the second approach, the I.T.E. EDINBURGH FOREST model,a previously published mechanistic model of plantation growthat the stand level (Thornley, 1991), is extended to naturalstands by introducing average stem birth and death rates thatare functions of the carbon and nitrogen substrate status oftrees. Growth of even-aged and mixed-age forest over about 500years is simulated under a variety of environmental and physiologicalconditions. In general, the forest model predicts a curved log m vs. logn thinning line, but has a reasonably well-defined linear sectionunder most conditions. The slope of the linear portion flattensas the rate at which cambium surface area scales with structuralbiomass increases, in qualitative agreement with the analyticalprediction of the first approach. Quantitative differences betweenthe two approaches are interpreted in terms of the process representedin the forest model. In general, the height of the thinningline increases with irradiance, but is relatively insensitiveto soil nitrogen, with no change in slope in either case. However,at very low irradiance or soil nitrogen levels, the slope flattenscontinuously and the entire thinning line becomes markedly non-linear.Even-aged stands and mixed-age stands have different thinningslopes.Copyright 1993, 1999 Academic Press Self-thinning, carbon balance, mechanistic model, forest growth, respiration     

Persistent Effects of Short-term, High Exposure to Chlorine Gas on Physiology and Growth of Pinus ponderosa andPseudotsuga menziesii

Following a single acute exposure to chlorine gas, persistenteffects on epicuticular waxes, cuticular transpiration, treegrowth and mortality were studied in foliage of Pinus ponderosaand Pseudotsuga menziesii for three growing seasons. Chlorinegas exposure caused foliar injury to both exposed foliage andfoliage that flushed after exposure (P < 0.05). The tendencyto form films of water rather than droplets was greater in directlyexposed foliage (P < 0.001). Rates of cuticular transpirationwere higher for directly and indirectly exposed foliage of Pinusponderosa up to 1 year after exposure and up to 6 months afterexposure for directly exposed Pseudotsuga menziesii(P < 0.001),after which P. menziesii needles defoliated. Total water content(TWC) and relative water content were significantly correlatedwith foliar injury (P < 0.05). TWC was lower for directlyexposed foliage up to 1 year after exposure (P < 0.001).There was no persistent negative effect on F_v/F_m ratios after1 year. Exposure to chlorine gas did not affect needle lengthor annual shoot increment growth, but exposure was correlatedwith increased bud production. Needle longevity of foliage thatflushed 2 months after exposure was reduced significantly (P< 0.001). Annual stem increment growth for both species decreasedover at least three growing seasons following chlorine gas exposure(P < 0.001), and depended on distance from the spill site.Cone production was lower for exposed Pinus ponderosa treescompared to controls (P < 0.05), and tree mortality was higherwithin approx. 50 m of the release site forPseudotsuga menziesii. Growth responses for both conifers agreed well with predictedpatterns of carbon allocation after defoliation caused by chlorinegas exposure. Copyright 2001 Annals of Botany Company Pinus ponderosa, Pseudotsuga menziesii, conifers, chlorine gas, leaf wettability, cuticular transpiration, water relations, growth, mortality     

Size-dependent Allometry of Tree Height, Diameter and Trunk-taper

The allometry of tree height with respect to trunk diameterand the allometry of trunk diameter with respect to distancefrom the top of the tree (i.e. trunk taper) were determinedfor 27 Robinia pseudoacacia trees differing in age and sizegrowing in an open field. The allometric (scaling) exponentfor height was > 1 for small and young trees and decreasedto 2/3 and then 1/2 as tree size and age increased. Similarly,the exponent for taper was > 1 near the tips of young andold trunks and converged onto values of 2/3 and 1/2 toward thebase of mature tree trunks. These observations indicate thata single 'optimal mechanical design principle' (i.e. elastic,stress or geometric self-similarity) neither holds true throughoutthe lifetime of R. pseudoacacia trees, nor does a single designprinciple govern the taper of a trunk throughout its entirelength. Rather, over the course of growth and development, theallometry of R. pseudoacacia tree height and trunk taper progressivelychanges, complying with geometric self-similarity for youngplants (and young portions of old plants) and subsequently givingthe appearance of elastic or stress self-similarity as plants(or portions of plants) get older and therefore larger. Analysesof published (and new) data suggest that the conclusions drawnfor R. pseudoacacia trees are likely to hold true for othertree species because stem growth in diameter is 'indeterminate'whereas growth in overall tree height is asymptotic and thereforeessentially 'determinate'.Copyright 1995, 1999 Academic Press Scaling, woody plants, Robinia pseudoacacia     

Ultrastructural Investigation of Tension Wood Fibre in Fraxinus mandshurica Rupr. var. japonica Maxim.

The ultrastructure of the fibre wall in Fraxinus mandshuricaRupr. var. japonica Maxim. was investigated by electron microscopy.The trees had been inclined artificially at an angle of 30°to the vertical at the beginning of the initiation of cambialgrowth in early spring. The secondary walls of tension woodfibres were of the outer (S₁) layer and gelatinous (G) layertype. The microfibrils in the gelatinous (G) layer were orientedas a steep Z-helix relative to the fibre axis with a deviationthat ranged from 0° to 25° but was mainly between 5°and 10°. The cross-sectional surface of tension wood fibresrevealed the relatively strong attachment of the G-layer tothe S₁ layer. The G-layer stained weakly with potassium permanganate.The S₁ layer of tension wood fibres stained less strongly thanthat of the normal and opposite wood fibres. These results indicatethat the tension wood in F. mandshurica var. japonica is nottypical and is somewhat anomalous. The secondary walls of normaland opposite wood fibres were composed of two layers, S₁ andS₂, and lacked an S₃ layer. Microfibrils in the S₃ layer ofjuvenile stems were extremely variable in orientation and weresparsely distributed without forming a layer. By contrast, avery thin S₃ layer was present in the wood fibres of maturestems. The variations in the formation of the S₃ layer in thefibre walls were probably due to the differences in the cambialage of the stems of F. mandshurica Rupr. var. japonica.Copyright1995, 1999 Academic Press Fraxinus mandshurica Rupr. var. japonica Maxim., Japanese ash, tension wood, fibre wall, G-layer, microfibrillar orientation, normal and opposite wood, juvenile stem, field-emission scanning electron microscopy, low accelerating voltage     

Maximum Vegetative Growth Potential and Seasonal Patterns of Resource Dynamics during Peach Growth

The maximum vegetative growth potential of two peach [Prunuspersica (L.) Batsch] cultivars that differ in the timing ofresource demand for reproductive growth was determined in termsof stem extension, stem and leaf dry weight accumulation, andtrunk radial increment on defruited trees. The maximum vegetativegrowth potentials were similar on the two cultivars indicatingthat the greater partitioning of dry weight to vegetative growthfrequently observed on early maturing cultivars compared tolate maturing cultivars is the result of a shorter period ofcompetition between reproductive and vegetative growth, ratherthan a genetic difference in vegetative growth potential. Onboth cultivars, stem extension and leaf dry weight accumulationceased in mid-summer, however stem dry weight accumulation andtrunk radial increment increase continued through the autumn. The presence of fruit did not have a detectable effect on thefinal stem length, stem dry weight or leaf dry weight on theearly maturing cultivar, but it reduced final stem length anddry weight by 43 and 56%, respectively on the late maturingcultivar. The presence of fruit did decrease stem length, stemdry weight and leaf dry weight on the early maturing cultivarfor 1 month prior to and 1 month after fruit harvest. Fruitdecreased final trunk radial increment by 42 and 77% on theearly and late maturing cultivars, respectively. These reductionsin vegetative growth indicate that resource partitioning tovegetative growth was reduced by competition with fruit growth. Comparison of stem relative extension rates and stem and leafrelative growth rates on fruited and defruited trees indicatedthat vegetative growth was resource-limited shortly after vegetativebud break on fruited trees of both cultivars. This period ofresource-limited vegetative growth corresponded to a periodof resource-limited fruit growth identified in an earlier study.During the period of resource-limited vegetative growth, assimilatesupply was low due to low leaf area index, and carbohydratedemand was relatively high due to high vegetative and reproductivegrowth potentials, creating resource-limited growth conditions.Copyright1995, 1999 Academic Press Maximum vegetative growth potential, carbon economy, partitioning, resource availability, resource limitation, source-limited growth, growth analysis, relative growth rate, peach, Prunus persica (L.) Batsch     

Simulation and Prediction of Plant Phenology for Five Crops Based on PhotoperiodxTemperature Interaction

This paper presents a plant phenological model based on genotypextemperaturexphotoperiodinteraction (GPTmodel). In the model, rate of development towardsa specified stage (e.g. flowering) for a given genotype is composedof three components: the genotype's maximum rate of development;any delay due to a non-optimal temperature; and any delay dueto a photoperiod response. It is assumed that development tothe specified stage is an autonomous process established bymost, if not all, genes other than the vernalization genes andthe photoperiod genes; and that this autonomous process is delayedby any activity of the photoperiod genes. Since all physiologicalprocesses are modulated by temperature, any photoperiod responseis inevitably a photoperiodxtemperature interaction. This interactionis simulated by assuming that the photoperiod gene activityoccurs only beyond a critical photoperiod (P_c) and is enlargedby temperature above a base temperature (T_bp) that allows thephotoperiod gene activity. The model is written asR=1/D_b-S_t(T-T_opt)²-S_p(T-T_bp)|P-P_c|, whereRis the expected rate of development to the specifiedstage under any combination of temperature (T) and photoperiod(P). The other model parameters are:S_p, the sensitivity to adelaying photoperiod;T_opt, the optimum temperature for developmentin the absence of the photoperiod response;S_t, the sensitivityto a non-optimum temperature; andD_b, the basic duration to thespecified stage (or intrinsic earliness), the inverse of whichis the maximum rate of development.D_bis observable only ifT=T_optandsimultaneouslyP     

The Mechanisms of Apple Bud Morphogenesis: Analysis and a Model

Information in the literature suggests that the process of applebud morphogenesis is controlled by the level of growth substances,notably gibberellins in the bud, and by the availability ofgrowth substrate (S). The spur buds of apples must contain acertain minimum number of nodes (N_m) before flower primordiacan be formed, and the process of bud morphogenesis can be describedby a rate of node production with time, t by the equation It is postulated that the parameter k_G is a function of thebalance between the enzymes systems in the bud, the rate ofsynthesis of the enzymes associated with the development offloral bud parts (floral enzymes) being inversely related tothe level of gibberellins (G) in the bud. The parameter k_G isa function of the nutritional state of the bud; a is a rateparameter, and i is a conversion factor. Node production rateis asymptotic with increase in S, but switches from high tolow values as G varies about a critical concentration. The implicationsof the model, which appears to describe most observations, arediscussed, and some suggestions for testing it are put forward.     

Identification of Stylar RNases Associated with Gametophytic Self-Incompatibility in Almond (Prunus dulcis)

Stylar proteins of 13 almond (Prunus dulcis) cultivars withknown S-genotypes were surveyed by IEF and 2D-PAGE combinedwith immunoblot and N-terminal amino acid sequence analysesto identify S-RNases associated with gametophytic self-incompatibility(SI) in this plant species. RNase activities corresponding toS_a and S_b, two of the four S-alleles tested, were identifiedby IEF and RNase activity staining. The S_a-RNase band reactedwith the anti-S₄serum prepared from Japanese pear (Pyrus serotina);no reaction with the antiserum was observed with the s_bRNaseband. When the s_a-RNase band was excised from an IEF gel stainedfor RNase activity, subjected to SDS-PAGE, and detected by immunoblotting,it appeared that this band consisted of a single protein thatreacted with the anti-s₄serum with M_r of about 28 kDa. With2D-PAGE and silver staining of the stylar extracts, all fourS-proteins could be successfully distinguished from each otherin the highly basic zone of the gel. Although S_b-, S_c-, andS_dproteins had roughly the same M_r of about 30 kDa, the S_c-proteinseemed to be slightly smaller than the S_b-protein and slightlylarger than the S_aprotein. In 2D-PAGE profiles as well, theS_a-protein had M_r of about 28 kDa, apparently smaller than theother three proteins. A bud sport, in which one of the two S-allelesof the original cultivar is impaired, was visualized as a lossof S_cprotein, which is consistent with the previous pollinationstudy. All four S-proteins reacted with the anti-S₄serum, probablybecause of the differing conformations of these S-proteins inthe IEF and 2D-PAGE gels. The S_a-protein in 2D-PAGE appearedto be identical to S_a-RNase in IEF; both bad the same M_r andwere reactive with the anti-S₄-serum. N-terminal amino acidsequence analysis of the four 5-proteins revealed that theywere highly homologous to each other and similar to the 5-RNasesof Malus, Pyrus, Scrophulariaceae, and Solanaceae. Taken together,RNases in the style are strongly suggested to be associatedwith the gametophytic SI of al- mond. This is the first reportidentofiying and characterizing S-RNase in almond. (Received July 11, 1996; Accepted December 26, 1996)     

Existence of a Common Glycoprotein Homologous to S-Glycoproteins in Two Self-incompatible Homozygotes of Brassica campestris

S-Glycoproteins (S-locus-specific glycoproteins) in Brassicaspecies are present only in stigmas and thought to play an importantrole in self-incompatibility system. The stigma extract containsalso several other glycoproteins reacting with the antiserumto S-glycoproteins, among which some glycoproteins from S₈S₈-and S₉S₉-homozygotes have the same pI value. Both of the glycoproteinswhich were tentatively termed NS₈- and NS₈S₉-glycoproteins,respectively, were isolated and analyzed. Those were revealedto be identical. Its amino acid sequence was homologous withthe S-glycoproteins in Brassica species. The NS-glycoproteinswere expressed at the same time and only in stigma as S-glycoproteins. (Received July 19, 1988; Accepted September 7, 1988)