Starch Synthesis During Dormancy Breakage in Oilseed of Corylus avellana

Dormancy in seed of Corylus avellana L. (hazel) is broken bya sustained period of cold stratification. During this timeboth cytological and metabolic changes occur. Starch was presentinitially at a low level but increased by 20% in the embryonicaxes of hazel seeds during stratification at 5 °C, whileit decreased rapidly and then remained constant in the embryonicaxes from seeds held at 20 °C. Histochemical study confirmedthis analytical result. A comparison of the developmental patternof starch level with bound and soluble ADP glucose-starch synthaseactivity at 5 and 20 °C showed that the accumulation ofstarch in the embryonic axes followed an enhanced activity ofthe granule-bound ADP glucose-starch synthase. Cold stratificationresulted in an increase in starch content, which was probablyas a result of gluconeogenesis from products of reserve lipidhydrolysis. Corylus avellana L., hazel, starch, ADP glucose-starch synthase, stratification     

Lipid Mobilization During Dormancy Breakage in Oilseed of Corylus avellana

During the stratification necessary for the alleviation of dormancyin Corylus avellana L. there is a substantial reorganizationof metabolic processes. Changes in activities of some enzymesrelated to lipid mobilization were followed throughout a fruitstratification period at 5 °C and control treatment at 20°C. Significant increases in total lipase and isocitratelyase activities were found in both embryonic axes and cotyledonsof seeds from fruits stratified at 5 °C, whereas the activitiesremained consistently low in those held at 20 °C. Theseresults correlated with an earlier ultrastructural study whichshowed a reduction in storage lipid. The increased potentialfor lipolysis was concomitant with loss of dormancy as seenin germination tests. These findings suggest that lipid mobilizationduring stratification could be related to the overall patternof metabolic changes which are required for dormancy release. Corylus avellana L., hazel, lipid, catalase, isocitrate lyase, lipase, stratification     

Light-Sensitivity of Hazel Seeds with Respect to the Breaking of Dormancy

Light breaks the dormancy of hazel (Corylus avellana L.) seedswhen the testa is removed. Light, acting via phytochrome, alsopromotes the germination of hazel seeds when the embryonic axisis surgically uncovered. In such seeds with the axis uncoveredremoval of the testa is antagonistic to the light promotionof germination. (Received January 17, 1982; Accepted April 25, 1983)     

Field Measurements of the Gas Exchange of Woody Plant Species in Simulated Sunflecks

The photosynthetic responses of eight tree and shrub speciesto simulated sunflecks was measured in the field. The net carbonexchange (NCE) of Corylus avellana and Ulmus glabra increasedwith irradiance up to the maximum irradiance of 230 µmolm^–2 s^–1. The NCE of Fraxinux excelsior, Hedera helixand the sun and shade forms of Rhododendron ponticum saturatedat about 120 µmol m^–2 s^–1 whereas the NCEof Ilex aquifolium, Daphne laureola and Fagus sylvatica hadeffectively saturated at 27 µmol m^–2 s^–1. In all cases the quantum efficiency of NCE could be predictedfrom measurements of chlorophyll fluorescence and the maximumvalue for NCE from measurements of stomatal conductance. Therelationships were combined into a model for predicting NCE/irradiancecharacteristics. Corylus avellana L., Daphne laureola L., Fagus sylvatica L., Fraxinus excelsior L., Hedera helix L., Ilex aquifolium L., Prunus laurocerasus L., Rhododendron ponticum L., Ulmus glabra Huds., gas exchange, stomatal resistance, water use efficiency, chlorophyll fluorescence, quantum efficiency     

Pollen-pistil Interaction in a Non-pseudogamous Apomict,Commiphora wightii

Structural and cytochemical details of the pistil and the interactionof pollen and pistil were studied in a non-pseudogamous apomict,Commiphorawightii.The anthers in the male and bisexual flowers producefunctional pollen grains. The stigma is of the wet and papillatetype. The style is typically solid with two strands of transmittingtissue that traverse the entire length of the style. There isa marked reduction in the area occupied by the transmittingtissue from the stigma to the base of the style. The cells ofthe transmitting tissue are isodiametric in transverse as wellas longitudinal section and do not form longitudinal files ofelongated cells as reported for other taxa. Proteins could notbe localized in the intercellular matrix. Although pollen grainsgerminate on the stigma, pollen tubes do not grow beyond theproximal one third of the style. Changed orientation of thecells of the transmitting tissue and absence of proteins inthe intercellular matrix could account for the failure of thepistil to support pollen growth.Copyright 1998 Annals of BotanyCompany Guggul, pollen-pistil interaction, non-pseudogamous apomict,Commiphora wightii, transmitting tissue     

The Structure and Cytochemistry of the Pistil of Sternbergia lutea (Amaryllidaceae)

Studies were carried out on structural and cytochemical aspectsof the pistil of Sternbergia lutea (L.) KerGawl. The stigmais of the wet papillate type; the papillae are unicellular andare arranged densely around the rim of a funnel-shaped stigma.The stigma exudate is limited and is confined to the bases ofthe papillae and the inner lining of the stigma. The papillaeare smooth in the distal part and are covered with intact cuticle-pelliclelining. The cuticle is disrupted at places towards the baseof the papillae releasing the exudate. The exudate is rich inpectins and other polysaccharides but poor in proteins and lipids.The papillae show dense cytoplasmic profiles with extensiveendoplasmic reticulum (ER), abundant mitochondria, polyribosomesand active dictyosomes. The style is hollow. The stylar cavityis surrounded by two to four layers of glandular cells. In theyoung pistil the canal is lined with a continuous cuticle, butin the mature pistil the cuticle becomes disrupted and the canalis filled with the secretion produced by the cells of the surroundingglandular tissue. Ultrastructurally, the cells of the glandulartissue are very similar to the stigmatic papillae. The innertangential wall of the cells bordering the canal is uniformlythicker than other walls. The secretion in the stylar canal,as well as the intercellular spaces of the glandular tissue,stain intensely for pectins and polysaccharides but poorly forproteins and lipids. Pollen tubes grow through the stylar canal.Structural and cytochemical details of the pistil of Sternbergiaare compared with other hollow-styled systems. Pistil, Sternbergia lutea (L.) Ker-Gawl., stigma and style, structure and cytochemistry     

The Anatomy, Histochemistry and Ultrastructure of Stigmas and Styles in Commelinaceae

The anatomy and ultrastructure of stigmas in 37 species of 13genera of Commelinaceae are described. The stigmas are papillate,papillae forming a dense fringe of cells around the mouth ofthe stylar canal in most species. The papillar cell wall iscovered by an unstructured cuticle of variable thickness andis of variable thickness because of small wall ingrowths. Thecuticle and the external surface of the papillar cell wall arevariably disrupted, particularly in the mid and basal regionsof the cell. This was not found in species of the genus Aploleiaor Callisia. The cell cytoplasm possesses all major organellesexcept chloroplasts and each cell is vacuolate. In all species except Aploleia mulitiflora the style comprisesan epidermis, a cortex and a hollow, tripartite canal whichis continuous into the ovary cavity. The three vascular strandsare positioned at the apex of each canal lobe. The canal cellsare elongate and tabular and the wall abutting the canal hasingrowths. The style in Aploleia is solid and the transmittingtissue comprises cells whose walls are electron opaque. Thecytoplasms of both types of cell are similar in content althoughthere is a single, large vacuole in canal cells and many smallvacuoles in transmitting tissue. The morphology, position and histochemistry of stigmatic andstylar exudate was similar in all ‘wet’ stigmas.Most of the exudate originates from the stylar canal althoughsignificant contributions are made by the papillae in stigmasof Coleotrype, Dichorisandra and Thyrsanthemum. There is no apparent relationship between stigma structure andthe presence of self-incompatibility. Stigma papillae, stylar canal, transmitting tissue, Commelinaceae     

Pollination Biology in a TropicalAcaciaHybrid (A. mangiumWilld. xA. auriculiformisA. Cunn. ex Benth.)

Floral biology and pollination mechanism of theAcaciahybrid(A. mangiumWilld. xA. auriculiformisA. Cunn. ex Benth.) growingin Thailand are investigated using light and electron microscopy.The hybrid is andromonoecious. A floral spike consists of about150 loosely arranged flowers. Flowers are cream coloured, fragrantand have no floral nectaries. The pistil has a solid style witha smooth, wet stigma and amphitropous ovules with immature integuments.The anther consists of eight loculi, each bearing only one 16-grainpolyad. The flowers are weakly protogynous. Anthesis is completeat 0500–0600 h but peak female receptivity begins at 0200–0300h and is completed that day. The stigmatic exudate is of thelipophilic type and is secreted from the stigmatic cells bya holocrine mechanism. Pollen is the main floral reward forthe insect pollinators. There are several floral characteristicswhich facilitate pollen transfer from anthers and depositionon stigmas.Apis melliferaandCeratinasp. are the most effectivepollinators because they are the most common visitors and carrya heavy load of hybrid polyads. However, their behaviour inforaging for pollen in the same tree and weak protogynous dichogamymay promote self-pollination in the hybrid. The hybrid has lowpollination success due to low pollinator number. An increasein exposure time of flowers to pollinators or pollinator numbermay increase pollination success but may not affect the rateof pollen deposition on stigmas due to the relatively smallsize of the stigma in relation to the polyad.Copyright 1998Annals of Botany Company Acaciahybrid,Acacia mangium, Acacia auriculiformis, pollination, pistil receptivity, anthesis, pollinators.     

Characterization and Estimation of Newly Synthesized DNA in Higher Plant Protoplasts During the Initial Period of Culture

A double-labelling technique is described for the quantitativeestimation of DNA synthesized by protoplasts of Corylus avellanaL. The quantity of new DNA, labelled with [³²P]orthophosphate,is expressed with respect to that of pre-existing DNA, labelledwith [³H]thymidine supplied to the callus from which the protoplastswere prepared. The estimation of DNA, isolated by agarose gelchromatography instead of acid-precipitation, is more reliableand precise. DNA synthesis by protoplasts increases steadilyfor the duration of the experiment (120 h) and no synchronyis apparent. Endolytic degradation of DNA has been shown inprotoplasts of poor quality.     

Flora Palinologica Italiana. Schede diCorylus avellana L. cv. Tonda Gentile delle Langhe (TGL) eCorylus maxima Miller e valutazioni statistiche

Riassunto Si sono allestite le schede morfopalinologiche compilate secondo le norme della ?Flora Palinologica Italiana?, perCorylus avellana L. cv. TGL eCorylus maxima Miller per polline acetolizzato e fresco. Le due specie rivestono interesse agronomico anche per l'ottenimento di ibridi interspecifici. La differenza del rapporto P/E fra le due entità risulta altamente significativa Tuttavia non è possibile un riconoscimento dei due tipi pollinici direttamente in analisi aerosporologiche.

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Summary Palynological cards ofCorylus avellana cv. TGL andCorylus maxima Miller are presented for fresh and acetolyzed pollens, according to the project ?Flora Palinologica Italiana?. Both species are interesting from the agricultural point of view, also for the possibility to obtain interspecific hybrids. The difference of the P/E ratio between the two entities is highly significant. In sprite of this fact, is not possible to discriminate the two pollen types in aerosporological analysis for their extreme similarity.

     

Hormonal Regulation of Seed Dormancy in Hazel (Corylus avellana L.) and Beech (Fagus sylvatica L.)

Dormancy in seeds of hazel (Corylus avellana L.) and beech (Fagussylvatica L.) has been studied with special reference to changesin growth-promoting and inhibiting substances during after-ripening.About 12 weeks at low temperature and under moist conditionsis necessary for complete after-ripening. Gibberellic acid,kinetin, and thiourea stimulate germination in dormant seedsbut have no effect on nuts with the pericarp intact. Gibberellin‘D’ is ten times more active than gibberellic acid.Bio-assays, following chromatographic fractionation of seedextracts, have revealed no significant changes in the concentrationsof auxins and inhibitors during after-ripening. Dwarf maize-leafsection assays have revealed low concentrations of gibberellin-likesubstances in purified extracts of chilled, dormant hazel seedbut no gibberellin activity in extracts of dormant seed. Gibberellinsare present in both dormant and germinating beech seeds butthere appear to be differences in the chromatographic patternof activity. The possible role of endogenous gibberellins inthe after-ripening process is discussed.     

A Comparison of Petiolar Growth of Isolated Hazel Cotyledons in Response to Stratification and Exogenous GA3

Following stratification seeds of Corylus avellana exhibitedtheir characteristic ability to germinate at 20 °C undermoist conditions. Stratification of the intact fruit also stimulatedelongation of the cotyledonary petiole when isolated cotyledonswere transferred to moist conditions at 20 °C. GA₃ inducedboth of these effects in non-stratified material. ABA substantiallydecreased seed germination and the response of cotyledonarypetioles to stratification and GA₃. CCC² applied to stratifiedor GA₃-pretreated cotyledons did not depress the final percentageof growing petioles. Cotyledons can clearly regulate the development of their petiolesin the absence of the embryonic axis. It is concluded that thereis at least one gibberellin-sensitive site in the cotyledonscapable of initiating petiole development independent of axiscontrol.     

The Proteaceous Pistil: Morphological and Anatomical Aspects of the Pollen Presenter and Style of Eight Species Across Five Genera

The morphology and anatomy of pollen presenters, styles andpollen of species ofBanksia, Dryandra, Hakea, IsopogonandMacadamiawerestudied. Serial sections of pistils and SEM images of pollenwere quantified to determine whether the low fertility observedin the Proteaceae has a structural basis. Pollen access to thestigma was investigated. There were three types of stigmaticcavity. A groove in which the stigmatic papillae were enclosedwas present inDryandra, BanksiaandHakea. Macadamiahad a groovewith protruding papillae, andIsopogonhad a tube which enclosedthe papillae. Anatomical studies showed the pollen presenterto be structurally complex but overall to have similar internalanatomy across the species studied. The species could be groupedaccording to presence or absence of transfer tissue and presenceor absence of sclerenchyma, but these groups were not mutuallyexclusive. In the pistil there were three structural filtersto pollen tube passage. The first was at the stigma, where pollengrain access could be limited by the diameter or length of thestigmatic groove or the capacity of the pollination chamberin relation to pollen volume. The second and third related toa narrowing of the transmitting tissue tract within the pollenpresenter and in the lower style which could influence pollentube passage to the ovule.Copyright 1999 Annals of Botany Company Proteaceae,Banksia coccinea, Banksia ericifolia, Dryandra formosa, Dryandra nana, Dryandra quercifolia, Hakea bucculenta, Isopogon cuneatus, Macadamia integrifolia,stigmatic cavity, fertility, pollen presenter, structural limitation, stigma, pollen grain, image analysis, transfer tissue.     

Structural and Cytochemical Characteristics of the Stigma and Style in Vitis vinifera L. var. Sangiovese (Vitaceae)

Studies were carried out on structural and cytochemical aspectsof the stigma and style ofVitis vinifera . The stigma is ofthe wet papillate type with a continuous cuticle and pellicle.During the development of the papillae, the cell walls increasein thickness and produce a secretion product constituted oflipids that pass through the wall forming the exudate. The styleis solid with a central core of transmitting tissue which hasconspicuous intercellular spaces that increase remarkably fromthe periphery to the centre where the cuticle is present. Theintercellular spaces, where the pollen tubes grow, contain amatrix that includes polysaccharides, pectic substances andscattered areas of lipidic nature. Cytochemistry; stigma; style; ultrastructure; Vitis vinifera     

Tissue Development in the Stigma of Prunus avium L.

The tissue inside the stigma of Prunus avium L, through whichpollen tubes grow, undergoes a specific pattern of developmentwhich is different from that of the papillae on the stigmaticsurface or the transmitting tissue of the style in several importantaspects An elaborate system of intercellular spaces developsconsisting of small lacunae and aerenchymatous tissue The majorityof spaces contain no intercellular substances and appear tobe air canals, although the small lacunae may participate insecretion Aerenchymatous tissue on the peripheral regions ofthe stigma is characterized by several cytological featureswhich change during ontogeny, such as nuclear inclusions, amyloplastinclusions, dumbbell-shaped mitochondria, cytoplasmic sequestrationand isolated segments of endoplasmic reticulum Occasional clustersof amyloplasts were also observed Prunus avium L, sweet cherry, stigma, cytology, ultrastructure     

The role of air temperature in determining dormancy release and flowering ofCorylus avellana L.

Summary 7 years of airborne pollen monitoring in Perugia (central Italy) were used to determine the temperature requirements to break dormancy and to resume growth and bloom ofCorylus avellana L.,Corylus needs 1000 chill-units to complete its dormancy and this value, in the Perugian area, is met by the end of December or the first days of January. MoreoverCorylus trees require 220 growth degree hours before they are able to flower. If air temperature is high, this value can be achieved in only 10 days, but if the temperature remains too low, the heat accumulation can require up to 35 days. With these parameters it is possible to build a model to predict the date of the beginning ofCorylus avellana pollen season.     

AirborneCorylus pollen monitoring: Preliminary data

Summary In 1984–5 and 1985–6 aerosporological data were collected in an experimental hazel-nut orchard in Cravanzana (High Langa) whereCorylus maxima andCorylus avellana cv. Tonda Gentile delle Langhe (TGL) were present with a prevalence of the latter. Inter variety crosses withC. avellana and interspecific hybridsC. avellana xC. maxima were also present. CultivatedCorylus flowering diagrams are known, while more evidence is needed on the spread and concentration of airborne pollens, especially during female anthesis which spans over a month on average. Pollen release periods were identified including onset of accessory periods. Aerosporological data helped identify TGL association in relation to spread of plants and quality of nut. Cultivars and hybrids, which have already been studied in terms of genetic compatibility, have been considered in terms of airborne pollen periods. Thanks to adequate pollinators we can rationalize orchards, increase productivity while maintaining nut quality. This work has been supported by “Ministero della Pubblica Istruzione” found 60%.      

The Mechanical Properties of Xylem Tissue from Tobacco Plants (Nicotiana tabacum'Samsun')

Tobacco plants (Nicotiana tabacum‘Samsun’) havebeen grown with an antisense CAD (cinnamyl alcohol dehydrogenase)gene. This modifies lignin production, resulting in lignin witha greater aldehyde content which is easier to extract chemically.This lignin probably has a reduced crosslink density. The changedproperties of the lignin affect the longitudinal tensile modulusof the xylem tissue (wood), reducing it by one third, from 2.8GPa to 1.9 GPa. Tobacco xylem tissue cell walls are more sensitiveto changes in the properties of the matrix than can be predictedusing current cell wall mechanical models.Copyright 1998 Annalsof Botany Company Tobacco,Nicotiana tabacum, xylem tissue, Young's modulus, matrix polymer connectivity, plant biomechanics.     

Mechanism of Pollination in Gladiolus: Roles of the Stigma and Pollen-tube Guide

Gladiolus has a dry type of stigma. Compatible pollen grainsalight and germinate on the receptive surface of the papillae,penetrate the cuticle and grow towards the style through a sub-cuticularpollen-tube guide of mucilage. This is secreted from epidermalcells of the stylodium and style canal. The cuticle, which coversthe pollen tube guide mucilage, is continuous through the stylecanal to the ovary. The wet stigma of Lilium also has cuticulartissue running through the style canal, covering the mucilage.     

平欧杂种榛叶片解剖结构的抗旱性研究

为研究平欧杂种榛在新疆干旱地区的生态适应性,以新疆伊犁察布查尔县种质资源汇集圃内的38个品种(系)平欧杂种榛为试验材料,采用石蜡制片法,应用光学显微技术测定了叶片上表皮厚度、下表皮厚度、叶片厚度、主脉厚度、栅栏组织厚度、海绵组织厚度、栅栏组织厚度/海绵组织厚度(栅海比)、栅栏组织结构紧密度和海绵组织结构疏松度等9个抗旱相关的解剖结构特征参数,并进行统计分析和抗旱性综合评价。结果表明:(1)不同品种(系)主脉厚度、上下表皮厚度、叶片厚度、栅栏组织厚度和海绵组织厚度均表现出极显著水平差异,叶片上表皮厚度、下表皮厚度、叶片厚度、栅栏组织厚度和海绵组织厚度之间呈极显著相关和显著相关关系。(2)主成分分析表明,第1、2、3主成分的特征值分别为3.109、2.614和1.884,前3个主成分的累计贡献率达84.52%,基本能概括所有指标的主要信息。(3)采用聚类分析法将38个材料分成5大类;隶属函数法综合评价抗旱能力显示,材料84-48、81-21、84-310、F-03、B-11、85-162的抗旱性较强,材料85-127、85-88、B-21、80-4的抗旱性较差。