The role of miR156 in developmental transitions in Nicotiana tabacum

Plants undergo a series of developmental transitions during their life cycle. After seed germination, plants pass through two distinct phases: the vegetative phase in which leaves are produced and the reproductive phase in which flowering occurs. Based on the reproductive competence and morphological changes, the vegetative phase can be further divided into juvenile and adult phases. Here, we demonstrate that the difference between juvenile and adult phase of Nicotiana tabacum is characterized by the changes in leaf size, leaf shape as well as the number of leaf epidermal hairs(trichomes). We further show that miR156, an age-regulated microR NA, regulates juvenile-to-adult phase transition in N. tabacum. Overexpression of miR156 results in delayed juvenile-to-adult transition and flowering. Together, our results support an evolutionarily conserved role of miR156 in plant developmental transitions.     

Invasive Plants can Inhibit Native Tree Seedlings: Testing Potential Allelopathic Mechanisms

The mechanisms by which invasive species affect native communities are not well resolved. For example, invasive plants may influence other species through competition, altered ecosystem processes, or other pathways. We investigated one potential mechanism by which invasive plants may harm native species, allelopathy. Specifically, we explored whether native tree species respond differently to potential allelopathic effects of two invasive plant species. We assessed the separate effects of Lolium arundinaceam (tall fescue) and Elaeagnus umbellata (autumn olive) on three common successional tree species: Acer saccharinum (silver maple), Populus deltoides (eastern cottonwood), and Platanus occidentalis (sycamore). Tall fescue and autumn olive are widely planted and highly invasive or persistent throughout North America where they often grow in forest edges, old fields, and other sites colonized by pioneering tree species. In an exploratory greenhouse experiment, we applied aqueous extracts derived from soil, leaf litter, or live leaves to native trees. We compared these treatments to a sterile water control and also to minced leaves leached in water, a common, but potentially less realistic method of testing for allelopathy. For all tree species, minced leaves from tall fescue reduced the probability that seedlings emerged, and minced leaves of autumn olive reduced the number of days to emergence. During other demographic stages, the three native tree species diverged in their responses to the invasive plants. Platanus occidentalis exhibited the widest range of responses, with reduced root biomass due to minced tissue from both invasive species, reduced days to emergence and marginally reduced survival from minced tall fescue, and reduced leaf biomass from tall fescue leaf litter. Populus deltoides appeared insensitive to most extracts, although survival was marginally increased with application of minced or fresh leaf extracts from autumn olive. In addition, minced tall fescue shortened the time to seedling emergence for Acer saccharinum, potentially a positive effect. Overall, results suggest that allelopathy may be one mechanism underlying the negative impacts of tall fescue and autumn olive on other plant species, but that effects can depend strongly upon the source of allelochemicals and the tree species examined.     

Shoot morphology of Aucuba japonica incurred by anisophylly: ecological implications

Anisophylly, having leaves different in size and/or shape, was quantified in adult Aucuba japonica and simulations were carried out to evaluate the effects of anisophylly on the extent of self-shading at the single-shoot level as well as at the whole-canopy level. Clear anisophylly was observed in the individual after switching from the single-stemmed juvenile stage to the multi-stemmed adult stage. In such plants, leaf area in the canopy abruptly increased. The effective display of adult foliage involved a variety of morphological changes in addition to anisophylly, most prominently reduction in leaf size compared to juveniles. The simulation results indicate that diversity of leaf size and shape is an effective means of minimizing self-shading as well as allowing the efficient exploitation of a larger canopy volume in adult plants. Anisophylly also increased the biomass use efficiency of individual plants at maturity. Taken together, having diverse leaf forms is superior to having a single leaf form for maximizing area acquisition and for efficiently filling the acquired area. We therefore conclude that the anisophylly expressed in A. japonica is adaptive.     

Nitrogen resorption from leaves under different growth irradiance in three deciduous woody species

Resorption of nitrogen (N) from senescing leaves is an important conservation mechanism that allows plants to use the same N repeatedly. We measured the extent of N resorption in plants co-occurring in a beech forest to examine the variability of N resorption, especially in relation to growth irradiance. Measurements were done in three deciduous woody species; one adult and several juvenile trees of Fagus crenata and several adult trees of Lindera umbellata and Magnolia salicifolia. N resorption efficiency (R_EFF; percentages of leaf N that is resorbed during leaf senescence) did not differ significantly among leaves under different growth irradiances in any species we studied. R_EFF was affected by the growth stage of the tree in F. crenata with the values being consistently lower in juvenile trees than in the adult tree. N resorption proficiency (R_PROF; N concentration of dead leaves) converged to a similar value in F. crenata juvenile trees and M. salicifolia, irrespective of the presenescent leaf N concentration that was affected by growth irradiance. Again, R_PROF was lower (i.e. absolute N concentration was higher) in juvenile trees than in the adult tree in F. crenata. These results suggest that the growth irradiance does not place a great impact on the extent of N resorption, but the growth stage of the tree is influential in some species. The difference between the adult and juvenile trees may be ascribed to the size of N sink tissues, which is likely to increase with plant age.     

Variation in mesophyll anatomy and photosynthetic capacity during leaf development in a deciduous mesophyte fruit tree (<Emphasis Type="Italic">Prunus persica</Emphasis>) and an evergreen sclerophyllous Mediterranean shrub (<Emphasis Type="Italic">Olea europaea</Emphasis>)

The relative importance that biomechanical and biochemical leaf traits have on photosynthetic capacity would depend on a complex interaction of internal architecture and physiological differences. Changes in photosynthetic capacity on a leaf area basis and anatomical properties during leaf development were studied in a deciduous tree, Prunus persica, and an evergreen shrub, Olea europaea. Photosynthetic capacity increased as leaves approached full expansion. Internal CO₂ transfer conductance (g _i) correlated with photosynthetic capacity, although, differences between species were only partially explained through structural and anatomical traits of leaves. Expanding leaves preserved a close functional balance in the allocation of resources of photosynthetic component processes. Stomata developed more rapidly in olive than in peach. Mesophyll thickness doubled from initial through final stages of development when it was twice as thick in olive as in peach. The surface area of mesophyll cells exposed to intercellular air spaces per unit leaf area tended to decrease with increasing leaf expansion, whereas, the fraction of mesophyll volume occupied by the intercellular air spaces increased strongly. In the sclerophyllous olive, structural protection of mesophyll cells had priority over efficiency of photochemical mechanisms with respect to the broad-leaved peach. The photosynthetic capacity of these woody plants during leaf development relied greatly on mesophyll properties, more than on leaf mass per area ratio (LMA) or nitrogen (N) allocation. Age-dependent changes in diffusion conductance and photosynthetic capacity affected photosynthetic relationships of peach versus olive foliage, evergreen leaves maturing functionally and structurally a bit earlier than deciduous leaves in the course of adaptation for xeromorphy.     

Cytokinin-Regulated Mesophyll Cell Division and Expansion during Development of Cucurbita pepo Leaves

The role of cytokinins in the development of mesophyll structure was studied in developing pumpkin Cucurbita pepo L. leaves. Leaves were treated with cytokinins at different stages of growth: when they reached 25 or 50% of their final size (S _max), immediately after leaf growth ceased, and during senescence. At the early stages of leaf development, treatment with exogenous benzyladenine accelerated division of mesophyll cells. At the later stages of development, BA treatment activated expansion of growing cells and those, which have just accomplished their growth. The exogenous cytokinin did not affect the senescent leaf cells. The content of endogenous cytokinins changed during mesophyll development. The juvenile leaves (25% of S _max) were characterized by low level of these phytohormones. In the expanding leaves (50% of S _max), the content of phytohormones increased and decreased when leaf growth ceased. In the senescent leaves, the cytokinin content decreased markedly. It was concluded that the response of mesophyll cells to cytokinin depended on the cell growth phase at the moment of hormone action. Furthermore, in the young leaves, lower cytokinin concentrations were required for division of mesophyll cells in vivo than for cell expansion at the final stage of leaf development.     

The early phase change gene in maize

Recessive mutations of the early phase change (epc) gene in maize affect several aspects of plant development. These mutations were identified initially because of their striking effect on vegetative phase change. In certain genetic backgrounds, epc mutations reduce the duration of the juvenile vegetative phase of development and cause early flowering, but they have little or no effect on the number of adult leaves. Except for a transient delay in leaf production during germination, mutant plants initiate leaves at a normal rate both during and after embryogenesis. Thus, the early flowering phenotype of epc mutations is explained completely by their effect on the expression of the juvenile phase. The observation that epc mutations block the rejuvenation of leaf primordia in excised shoot apices supports the conclusion that epc is required for the expression of juvenile traits. This phenotype suggests that epc functions normally to promote the expression of the juvenile phase of shoot development and to suppress the expression of the adult phase and that floral induction is initiated by the transition to the adult phase. epc mutations are epistatic to the gibberellin-deficient mutation dwarf1 and interact additively with the dominant gain-of-function mutations Teopod1, Teopod2, and Teopod3. Genetic backgrounds that enhance the mutant phenotype of epc demonstrate that, in addition to its role in phase change, epc is required for the maintenance of the shoot apical meristem, leaf initiation, and root initiation.     

The role of abscisic acid and plant growth regulators in tissue culture-induced rejuvenation of strawberry ex vitro

Plant growth regulators applied in vitro affected strawberry plant performance ex vitro for a period of up to 4 months. Benzyl-adenine and gibberellin enhanced juvenile characteristics; in general, more runners and monofoliolate leaves were produced, net photosynthesis was reduced, leaf diffusive resistance was increased and, on occasion, flowering was delayed. In contrast, abscisic acid and a gibberellin biosynthesis inhibitor, paclobutrazol, resulted in a more adult phenotype; specifically, flowering was earlier, net photosynthesis and leaf diffusive resistance rates were equal to those of adult plants, and fewer leaves were monofoliolate. Tissue culture-produced plants reacquire the adult phenotype earlier than seedlings mature. Abscisic acid application to seedlings also resulted in earlier and increased flowering.Endogenous abscisic acid concentrations were greater in adult plants and less in tissue culture and seedling plants at 3 and 7 weeks ex vitro, after germination or after adult runner propagation. No flowering occurred at 3 weeks in any propagation type and only runner-produced plants flowered at 7 weeks. At 15 weeks, no statistical difference in abscisic acid concentrations existed among propagation treatments and all propagation types flowered. The endogenous concentrations of abscisic acid in plants propagated by all three methods were much higher at three weeks compared to concentrations at 7 or 15 weeks.Abbreviations ABA +cis, trans-abscisic acid - BA benzyl-adenine - GC-SIM-MS combined gas chromatography-selected ion monitoring mass spectrometry - GA gibberellin A₃ - RS leaf diffusive resistance in sec cm^-1 - MS Murashige & Skoog medium devoid of plant growth regulators - Pn net photosynthesis in mol CO₂ fixed m^-2 sec^-1 - paclo paclobutrazol as 50WP - TC-plants plants produced from tissue culture - Tween20 polyoxyethylene-sorbitan monolaurate - RP runner plants - SDLG selfed seedlings     

Characterization of microstructure and cell wall components of Arabidopsis thaliana overexpressing cyclin-dependent kinase inhibitor 2

Overexpression of a cyclin-dependent kinase inhibitor (KRP2) caused changes in the general morphology in the leaves of Arabidopsis thaliana. The wild type plant had obovate leaves with entire margins whereas the transgenic line had leaves with denticulate margins. The epidermal cells and stomata of the adult transgenic leaves were significantly larger than those of the wild-type plants and the number of stomata was in proportion to the number of epidermal cells. No apparent differences in thickness and structure of cell walls of the mesophyll cells between the two samples were observed. The smaller amount of cell wall material in the transgenic leaves caused by the larger cell size was also apparent in the lower dry weight of the transgenic leaves. The chemical analysis revealed the main differences to be in pectin and neutral sugar contents, and especially in the amounts of glucose, all being higher in the leaves of the KRP2 transgenic plants. p-Coumaric acid content varied more in the transgenic leaf material than in the control one reflecting possibly fewer cross-links in the cell walls of transgenic plants.     

Stylet penetration and survival of three psyllid species on adult leaves and `waxy'' and `de-waxed'' juvenile leaves of Eucalyptus globulus

The stylet probing behavior and survival of Ctenarytaina eucalypti Maskell, C. spatulata Taylor and Glycaspis brimblecombei Moore (Homoptera, Psyllidae) on adult leaves and `waxy' (untreated) and `de-waxed' (rubbed) juvenile leaves of the heteroblastic plant Eucalyptus globulus Labillardiere were compared. Psyllids were confined within clip-on cages and after 15 days the leaf tissue under each cage was sectioned and stained to characterize and quantify stylet tracks. Across all leaf treatments and psyllid species 1438 stylet tracks were observed in 7239 leaf sections and 571 of these stylet tracks reached the vascular tissue. Survival and the number of stylet tracks of C. eucalypti on the different leaf types did not differ. In contrast, C. spatulata survived significantly longer and produced significantly more stylet tracks on adult leaves and `de-waxed' juvenile leaves than on `waxy' juvenile leaves. Although G. brimblecombei survived equally on all treatments, it produced more stylet tracks on adult leaves and `de-waxed' juvenile leaves than on `waxy' juvenile leaves. For all three psyllid species, there was a positive correlation between survival and number of stylet tracks reaching the vascular tissue. Stylet tracks of all species were generally intercellular from the leaf epidermis to the vascular tissue. Oil glands were avoided by all species, as indicated by the repeated branching and formation of stylet tracks at the periphery of the glands. In `de-waxed' juvenile leaves, C. spatulata and G. brimblecombei produced stylet tracks that entered the leaf at the adaxial surface and exited at the abaxial surface. This pattern was rarely observed on adult leaves, and never occurred with C. eucalypti in any leaf type. We conclude that (1) the epicuticular wax on juvenile leaves reduced stylet probing by C. spatulata and G. brimblecombei, (2) there were apparently no internal physical barriers in either juvenile or adult leaves to prevent the stylets of any of the psyllid species from reaching the vascular tissue, (3) the psyllids avoided oil glands in both leaf types, and (4) C. spatulata and G. brimblecombei may lack cues to orient their stylets towards the vascular tissue in the juvenile leaves.     

Precocious flowering of juvenile citrus induced by a viral vector based on Citrus leaf blotch virus: a new tool for genetics and breeding

The long juvenile period of citrus trees (often more than 6 years) has hindered genetic improvement by traditional breeding methods and genetic studies. In this work, we have developed a biotechnology tool to promote transition from the vegetative to the reproductive phase in juvenile citrus plants by expression of the Arabidopsis thaliana or citrus FLOWERING LOCUS T (FT) genes using a Citrus leaf blotch virus‐based vector (clbvINpr‐AtFT and clbvINpr‐CiFT, respectively). Citrus plants of different genotypes graft inoculated with either of these vectors started flowering within 4–6 months, with no alteration of the plant architecture, leaf, flower or fruit morphology in comparison with noninoculated adult plants. The vector did not integrate in or recombine with the plant genome nor was it pollen or vector transmissible, albeit seed transmission at low rate was detected. The clbvINpr‐AtFT is very stable, and flowering was observed over a period of at least 5 years. Precocious flowering of juvenile citrus plants after vector infection provides a helpful and safe tool to dramatically speed up genetic studies and breeding programmes.     

Cytology of induced systemic resistance of tomato to Phytophthora infestans

The infection of tomato leaves by Phytophthora infestans was followed using cytological methods. Fungal ingress and plant reactions in untreated and induced resistant plants were studied. Systemic disease resistance was induced by a local pre-infection with the same fungus. Induction retarded fungal progress at the leaf surface, epidermis and in the mesophyll. The reduced numbers of germinated cysts indicate the presence of fungitoxic substances on the leaf surface of induced plants. Frequency of fungal penetration through the outer epidermal cell wall was reduced, but only in plants exhibiting a high level of induced resistance. Autofluor-escent material, indicating the presence of lignin-like substances, accumulated rapidly beneath some of the appressoria, but this plant response was similar in induced and non-induced plants. Staining with aniline blue indicated that callose deposition was not involved in induced resistance. Thus, none of the cytologically investigated plant reactions correlated with the reduced penetration frequency observed. In the mesophyll, however, the cytological picture corresponding to a hypersensitive reaction occurred more often in induced plants. It is concluded that reduction of disease severity by induction is the result of the combined action of several successive defence reactions.Dedicated to the memory of Professor H. Grisebach     

Developmental anatomy of cotyledons and leaves in has mutant of Arabidopsis thaliana

Summary. In this work, we analyzed the developmental anatomy of cotyledons and leaves in the has mutant of Arabidopsis thaliana. It is a recessive T-DNA insertion mutation that causes changes in the size, shape, and tissue organization of the cotyledons and leaves of has plants. Analysis of has cotyledons revealed a prominent decrease in the cell number and an increase in the area of cotyledon cells and intercellular spaces of has plants. At early stages of development, has leaves are fingerlike structures, but later they develop small, lobed blades with rare trichomes. An important characteristic of the mutant leaf anatomy is the absence of mesophyll tissue differentiation. In addition, both cotyledons and leaves display a disrupted pattern of vascular bundles. Furthermore, mutant plants are defective in root and shoot morphology, indicating that the has mutation affects a number of aspects in plant development. Correspondence and reprints: Institute of Botany and “Jevremovac” Botanical Garden, Faculty of Biology, Belgrade University, Takovska 43, 11 000 Belgrade, Serbia.     

Microarray analysis of vegetative phase change in maize

Vegetative phase change is the developmental transition from the juvenile phase to the adult phase in which a plant becomes competent for sexual reproduction. The gain of ability to flower is often accompanied by changes in patterns of differentiation in newly forming vegetative organs. In maize, juvenile leaves differ from adult leaves in morphology, anatomy and cell wall composition. Whereas the normal sequence of juvenile followed by adult is repeated with every sexual generation, this sequence can be altered in maize by the isolation and culture of the shoot apex from an adult phase plant: an 'adult' meristem so treated reverts to forming juvenile vegetative organs. To begin to unravel the as-yet poorly understood molecular mechanisms underlying phase change in maize, we compared gene expression in two juvenile sample types, leaf 4 and culture-derived leaves 3 or 4, with an adult sample type (leaf 9) using cDNA microarrays. All samples were leaf primordia at plastochron 6. A gene was scored as 'phase induced' if it was up- or downregulated in both juvenile sample types, compared with the adult sample type, with at least a twofold change in gene expression at a P-value of < or =0.005. Some 221 expressed sequence tags (ESTs) were upregulated in juveniles, and 28 ESTs were upregulated in adults. The largest class of juvenile-induced genes was comprised of those involved in photosynthesis, suggesting that maize plants are primed for energy production early in vegetative growth by the developmental induction of photosynthetic genes.     

Pleiotropic effects of flowering time genes in the annual crucifer Arabidopsis thaliana (Brassicaceae)

Variation in flowering time of Arabidopsis thaliana was studied in an experiment with mutant lines. The pleiotropic effects of flowering time genes on morphology and reproductive yield were assessed under three levels of nutrient supply. At all nutrient levels flowering time and number of rosette leaves at flowering varied among mutant lines. The relationship between these two traits depended strongly on nutrient supply. A lower nutrient supply first led to an extension of the vegetative phase, while the mean number of leaves at flowering was hardly affected. A further reduction resulted in no further extension of the vegetative phase and, on average, plants started flowering with a lower leaf number. At low nutrients, early flowering affected the timing of production of siliques rather than the total output, whereas late flowering was favorable at high nutrients. This may explain the fact that many plant species flower at a relatively small size under poor conditions. Flowering time genes had pleiotropic effects on the leaf length, number of rosette and cauline leaves, and number of axillary flowering shoots of the main inflorescence. Silique production was positively correlated with the number of axillary shoots of the main inflorescence; the number of axillary primordia appeared to have a large impact on reproductive yield.     

Light acclimation in leaves of the juvenile and adult life phases of ivy (Hedera helix)

Hoflacher, H. and Bauer, H. 1982. Light acclimation in leaves of the juvenile and adult life phases of ivy (Hedera helix). – Physiol. Plant. 56: 177–182. Light acclimation was investigated during the juvenile and adult life phases of the whole-plant-development in Hedera helix L. For this purpose, cuttings of the juvenile and adult parts of one single parent plant were grown under low-light (PAR 30–50 μmol photons m^?2 s^?1) and high-light (PAR 300–500 μmol m^?2 s^?1) conditions: CO₂ exchange, chloroplast functions, and specific anatomy of fully developed leaves differentiated under these conditions were determined. In juvenile plants the leaves formed under low and high light had light-saturated rates of net photosynthesis of 6.5 and 11.1 mg CO₂ (dm leaf area)^?2 h^?1, respectively. In adult plants the rates were 9.4 and 22.2 mg dm^?2 h^?1, indicating a more pronounced capacity for acclimation to strong light in the adult life phase. Higher photosynthetic capacities were accompanied by higher conductances for the CO₂ transfer through the stomata, leading to almost the same CO₂ concentration in the intercellular spaces. Thus, stomatal conductances were not primarily responsible for the different photo-synthetic capacities. The higher rates in adult and high-light grown leaves were mainly the result of formation of thicker leaves with more chloroplasts per unit leaf area. Expressed per chloroplast, the photosynthetic capacity, the Hill reaction, and the activity of ribulose bisphosphate carboxylase were almost identical in plants grown in low-light and high-light. Measurements of photosynthetic capacity and thickness of leaves of Hedera sampled from field habitats with contrasting light regimes confirm the results of growth chamber studies. It is, therefore, concluded that both life phases of Hedera are capable of acclimating to strong light, but that during the juvenile phase this capacity is not fully developed.     

Early stages of leaf development in <Emphasis Type="Italic">has</Emphasis> mutant of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

The elucidation of molecular mechanisms underlying the leaf development can be facilitated by the detailed anatomical study of leaf development mutants. We present an analysis of leaf anatomy and morphogenesis during early developmental stages in has mutant of Arabidopsis thaliana. The recessive has mutation affects a number of aspects in plant development, including the shape and size of both cotyledons and leaves. The earliest developmental observations suggest almost synchronous growth of the first two leaf primordia of has mutant. No significant disruption of the cell division pattern in the internal tissue is observed at the earliest stages of development, with the major anatomical difference compared to wild type primordia being the untimely maturation of mesophyll tissue cells in has mutant. At the stage of leaf blade formation, structure disruption becomes clearly evident, by irregular arrangement of the cell layers and the lack of polarity in juvenile has leaves. One distinguishing feature of the mutant leaf anatomy is the absence of mesophyll tissue differentiation. Altered has mutant leaf morphology could be at least partially accounted for by the ectopic STM activity that was found at the base of leaf primordia during early stages of leaf development in has plants.     

Endogenous cytokinins in the vegetative and reproductive phases of development in the dioecious plant Rumex acetosella L.

The content of endogenous cytokinins has been analysed in leaf and inflorescence extracts of male and female R. acetosella plants, using gas chromatography. Plant parts were extracted at four stages of development: leaves of juvenile plants, leaves of adult plants at the time of flower initiation and in full bloom, and upper internodes of the inflorescence stalks. Cytokinins with characteristics similar to isopentenyl adenine and adenosin, zeatin, zeatin riboside, and a bound form of zeatin, were all found in the extracts. The total amount of cytokinins was higher in female than in male plants during all these stages.Reprint requests     

Ontogenetic differences in mesophyll structure and chlorophyll distribution in Eucalyptus globulus ssp. globulus

Mesophyll structure has been associated with the photosynthetic performance of leaves via the regulation of internal light and CO(2) profiles. Differences in mesophyll structure and chlorophyll distribution within three ontogenetically different leaf types of Eucalyptus globulus ssp. globulus were investigated. Juvenile leaves are blue-grey in color, dorsiventral (adaxial palisade layer only), hypostomatous, and approximately horizontal in orientation. In contrast, adult leaves are dark green in color, isobilateral (adaxial and abaxial palisade), amphistomatous, and nearly vertical in orientation. The transitional leaf type has structural features that appear intermediate between the juvenile and adult leaves. The ratio of mesophyll cell surface area per unit leaf surface area (A(mes)/A) of juvenile leaves was maximum at the base of a single, adaxial palisade layer and declined through the spongy mesophyll. Chlorophyll a + b content showed a coincident pattern, while the chlorophyll a:b ratio declined linearly from the adaxial to abaxial epidermis. In comparison, the mesophyll of adult leaves had a bimodal distribution of A(mes)/A, with maxima occurring beneath both the adaxial and abaxial surfaces within the first layer of multiple palisade layers. The distribution of chlorophyll a + b content had a similar pattern, although the maximum ratio of chlorophyll a:b occurred immediately beneath the adaxial and abaxial epidermis. The matching distributions of A(mes)/A and chlorophyll provide further evidence that mesophyll structure may act to influence photosynthetic performance. These changes in internal leaf structure at different life stages of E. globulus may be an adaptation for increased xeromorphy under increasing light exposure experienced from the seedling to adult tree, similar to the characteristics reported for different species according to sunlight exposure and water availability within their native habitats.