Influenza Dei Tegumenti Dell'Embrione Sull'Azione Dei Raggi X In Semi Di Triticum Durum Desf

Abstract

Influence of seed coats on the effect of X-rays on the embryo of «Triticum durum» Desf. – Seeds of «durum» wheat «Cappelli», presoaked in distilled water at 20° C. for 24 h in the dark, were treated with X-rays 0.5, 1, 2, 4 and 6 KR. Before irradiation, seeds were distributed among the following three groups: 1) normal seeds with covered embryos; 2) seeds to irradiate and afterwards to submit to the removal of seed coats (pericarp and spermoderm) on the embryo; 3) seeds to irradiate after having removed seed coats on the embryos. Of course, for every group, the respective unirradiated controls were prepared. The material was sown in sterilized sound and kept in termostatic chamber at 20°C in the dark, for 7 days. After 4 and 6 days the seedling emergence was registered, after 7 days seedling were measured. Of particular interest is the remarkable depressing effect on the growth of seedlings coming from bared and irradiated embryos: this effect is induced – for significant differences, as compared with the behaviour of materials of groups 1 and 2 – especially on the root, by X-rays 2, 4 and 6 KR. No difference there is, on the contrary, among the seedlings coming from irradiated and bared embryos and those coming from irradiated controls.     

Comportamento Alla Germinazione e Mutabilità Cromosomica Spontanea in Triticum Durum Desf. Durante I Primi Due Anni di Vita del Seme

Abstract

Germination and spontaneous chromosome mutations in Triticum durum Desf. during the first two years of storage of the seed. — Spontaneous chromosome aberrations were recently observed in the meristem of radicles of seedlings raised from seeds (caryopses) of Triticum durum cv. Cappelli erop 1966. Germination and frequency of chromosomal aberrations, starting from the ripening of the caryopses to the end of the second year of their storage at room temperature were investigated. Cytological analysis and germination tests were accomplished at monthly intervals. It was shown that: 1) soon after ripening, the germination process was very slow, but chromosomal damage was high; 2) at the end of the dormancy period the percentage of aberrant anaphases and of chromatid breaks fell to a «minimum». This low chromosomal damage lasted for almost the whole of the two years of storage; 3) the nuclear damage was esclusively of chromatide type. This result and fact that the cytological damage is decreasing with time, are interpreted as evidence that the mutagenic agent(s) responsible is (are) more active during the germination period than during the quiescence of the embryo.     

Nuove Prospettive Nello Studio dei Fattori che Controllano la Germinazione Dei Semi

Abstract

New perspectives in the study of factors which control seed germination. — Seedlings of Triticum durum, cv. « Cappelli », coming from unirradiated embryos grafted on to irradiated endosperms (EM(u)/EN(i) of presoaked seeds (in distilled water for 24 h. at 20[ddot]C.) (treatment: X-rays, doses, 2,4,6,8,10 and 20 Kr), grow more than seedlings of control EM(u)/EN(u) (dose 0) (fig. 1). To have this reaction, it is necessary that the used seeds be after-ripe; at the various stages of seed ripening, be ginning from the milk stage, the phenomenon is not present.

On this basis, the author has thought that a natural inhibitor occurs in the after-ripe endosperm of « Cappelli », which is neutralized or destroyed by X-rays.

As an experimental demonstration, some trials have been made of growing wheat seedlings in Petri dish, on moistened (distilled water) filter paper, together with excised embryos or isolated endosperms (fig. 2): the after-ripe endosperm is able to depress the seedling growth (fig. 3). In the same experimental conditions, X-rays, dose 6 Kr, neutralize the inhibition effect given by the endosperm. (fig. 4).

A completely different situation occurs in wheat seed, during its ripening: endosperm is inactive, embryo produces inhibition effects on the seedling growth, which, also in this case, are reduced by X-rays.

These phenomena, put in relation with dormancy in Triticum durum, cv. « Cappelli », which is a relative dormancy, having its maximum at the milk stage, have led the author to the general conclusion that, during dormancy, a germination inhibitor occurs in the embryo of wheat seed; when dormancy is finished, the inhibitor appears in the endosperm, in a situation which becomes stable and definitive.     

Prime indagini sul comportamento di embrioni isolati di Triticum Durum Cv. « Cappelli », provenienti da cariossidi normali e bianconate allevati artificialmente

Abstract

SOME INVESTIGATIONS ON THE BEHAVIOUR OF EXCISED EMBRYOS OF TRITICUM DURUM CV. « CAPPELLI », COMING FROM NORMAL GRAINS AND YELLOW BERRIES. — Excised embryos of Triticum durum cv. « Cappelli », coming from normal grains and yellow berries, soaking in distilled water for 24 hours, were brought up for 6 days in petri dishes, on a 1% solution of agar + glucose, at the constant temperature of 23°C, at the light of a common germicidal lamp. As controls, normal grains and yellow berries were utilized, placed in petri dishes each containing a piece of filter paper moistened with distilled water. After 6 days, the seedlings (measured the shoot and the longest root) were transferred to a greenhouse in sand, at daylight (average temperature: 16°-18°G.). After 14 days, the shoot and the longest root of each seedling coming from the sand cultures were measured.

The following results were obtained:

1. control seedlings: after 7 (1 + 6) days, the normal seedlings grow more than those coming from yellow berries and the shoots grow as the roots (see MELETTI e ONNIS 1961 a, b e c); after 21 days, the situation of the control seedlings is again completely regular (normal shoots are longer);

2. seedlings coming from excised embryos: differences of growth are not here, neither after 7 nor after 21 days, among seedlings coming from normal grains and yellow berries.

These data should allow to conclude that the embryos, coming from normal grains and yellow berries, grow in the same way. But the limits of the utilized technique (want of balance in the relations between shoot and root, low survival of the seedlings coming from the excised em bryos, which grow too little in respect of the controls) suggest to carry into other investigations on the same subject.     

Sugli Effetti Provocati Dallo Scambio Degli Embrioni Fra Cariossidi Normali E Bianconate Del Grano “Cappelli”

Abstract

Effects induced by the exchange of embryos between normal grains and yellow-berries of « Cappelli » (Triticum durum Desf.). — Normal grains of « Cappelli » give seedlings, the shoots of which are longer than those coming from yellow-berries (Meletti e Onnis, 1961, a). The exchange of embryos between the two grain types shows the influence of endosperm on the seedling growth: the normal endosperm stimulates, while the yellow-berries endosperm depresses. The causes of this phenomenon are to research probably within the limits of the relationship, at biochemical level, between embryo end endosperm, with special regard to a likely different hormonic situation in normal grains and yellow-berries.     

Conseguenze e Significato del Prolungamento Nella Durata della Dormienza in Triticum Durum Desf

Abstract

Consequences and significance of dormancy Prolongation in «Triticum durum» Desf. — Different environment conditions have effect on the dormancy duration: this has been ascertained also for durum wheat Cappelli. Starting from this acquisition, the author does the embryo exchange between seeds of Cappelli different for dormancy degree. It is demonstrated that there is a direct relation between dormancy degree and inhibition power of endosperm.     

The effect of potassium on germinating wheat embryos at different viability levels

The effect of potassium administration in early germination of wheat (Triticum durum L., cv. Appulo) was studied by incubating isolated embryos at different viability levels with 1 mM KC1. The stimulation of germination and growth in aged embryos by K⁺ was accompanied by a significant increase in (³H) leucine incorporation into protein and in phospholipid synthesis as evidenced by TLC analysis of embryo phospholipids extracted after 24 h of imbibition. The metabolic improvement mediated by the cation would in turn repair aging damage occurring at subcellular sites including membranes.     

Natural Ageing: Poly(A) Polymerase in Germinating Embryos of Triticum durum Wheat

The viability of seeds is associated with ageing and storageconditions. A loss of viability is accompanied by slow germination,reduced growth, and a decline in protein and poly(A)⁺RNA synthesis.This paper reports on the activity of poly(A) polymerase indry and germinating embryos of Triticum durum Desf. cv. Cappellicaryopses of different ages and viability. The enzyme was presentas a single form during ageing and germination. The poly(A)polymerase was active at decreasing levels in all aged dry embryos,in parallel with loss of viability. Its activity strongly increasedduring the germination only in viable embryos. The observedincrease was due to de novo synthesis of the enzyme. Poly(A)polymerase synthesis was low during germination of less viableembryos and absent in older ones. Reduced poly(A) polymeraseactivity in dry or germinated wheat embryos may cause a shorteningof poly(A) chains in vitro and a decline in poly(A)⁺RNA synthesis.Copyright1995, 1999 Academic Press Triticum durum Desf. cv. Cappelli, wheat, embryo, natural ageing, poly(A) polymerase     

Azione della luce sulla crescita allo stadio di plantula di un mutante clorofilliano di Triticum durum Desf

Abstract

ACTION OF LIGHT ON SEEDLING GROWTH IN A YELLOW-GREEN MUTANT OF TRITICUM DURUM DESF. — Dry grains of Triticum durum cv. « Cappelli » and its radiation-induced yellow-green mutant were sown in sand in four environment, different for light conditions (daylight, artificial light, ultraviolet rays, darkness), having all the same temperature (23°C.). Seven days after sowing, the following data were registered: a) growth (in cm.) of the shoot and of the longest root; b) fresh weight (in gr.) of shoots and roots; c) water content of shoots and roots.

The following main results were obtained:

1. the yellow-green mutant always shows less growth and less weight increase than normal « Cappelli », with the exception of the seedlings grown at daylight, which have shorter shoots and longer roots than the normal « Cappelli » but the same weight:

2. artificial light, besides depressing the growth of the roots of the yellow-green mutant, which becomes green under these conditions, induces a remarkable decrease in the water content of the roots of the two wheats.

     

Significance of achene characteristics and within-achene resource allocation in the germination strategy of tetraploid Aster pilosus var. pilosus (Asteraceae)

The interrelationships among achene weight, allocation to embryo and pericarp, and germination time were determined for 500 stratified achenes of tetraploid Aster pilosus Willd. var. pilosus. Only 52.6% of the achenes germinated. Germinated achenes were significantly heavier than ungerminated achenes. Germination time was independent of achene weight and embryo weight, but varied inversely with pericarp weight. Variable achene weight is evolutionarily advantageous. Heavy achenes are at an advantage in that their proportionately larger embryos and thinner pericarps facilitate germination, promoting competitive establishment of seedlings. Lighter achenes are also at an advantage through increased dispersibility, and their relatively thick pericarp provides a persistent seed bank. Evolutionary pressures presumably maintain the variability in achene weight of var. pilosus. These results are discussed in the context of the early midsuccessional ecology of var. pilosus.     

Polyamine metabolism during early germination of Triticum durum Desf. cv. Cappelli

Abstract

Changes in polyamine metabolism have been studied during early germination of Triticum durum Desf. cv. Cappelli. In the embryos of dry seeds, the adequate polyamine content decreases with a minimum at 36 h of water imbibition. A great need for polyamines during germination is expressed by reactivation of their biosynthetic enzymes. Putrescine biosynthesis mostly occurs via the ornithine–decar–boxylase pathway until 42 hours of hydration. Arginine–decarboxylase activity, almost absent in the first stages of imbibition, reaches its maximal level around 36–42 hours, when ornithine–decarboxylase falls. These changes suggest that the polyamine metabolism could be differently activated depending on the growth process related to the germination phases.     

Note Sui Grani a Spighe Ramificate

Resumé

Chez les Blés branchus de l'espèce «turgidum» (Triticum turgidum compositum), il existe des sortes à thermostade plutôt froid (Blés d'hiver ou de semi-hiver) et des sortes à thermostade chaud, tièe ou «indifférent» (Blés de printemps).

Les Blés branchus de l'espèce «turgidum» apparaissent comme étant des plantes à photostade de jour long.

La plus ou moins grande rapidité de l'accomplissement du photostade, par rapport à la rapidité de l'assimilation des matières plastiques, détermine la structure, — non ramifiée ou ramifiée — de l'épi.     

Osservazioni Sull'Assunzione Dell'Acqua Durante le Prime Fasi Di Germinazione Di Semi Di Pinus Pinea L

Abstract

Water assumption during the early germination stages in «Pinus pinea» L. seeds. – Germination of «Pinus pinea» L. seeds in several conditions has been studied. The main results attained are the following: 1) The micropyle appears to be the only water way into the seed, to start root growth. When this route is prevented and water is absorbed only by the seed surface, the embryo grows into a big cotyledon-hypocotyl complex, where the radicle is still blocked in the embryonic stage; 2) The micropyle appears to be involved also in gas exchange processes during germination.     

Sulla Presenza di Ificellarioli e di Conidi in Mieobionti Lichenici Coltivati in « Vitro ». Riassunto

Abstract

On the presence of « hyphycellariola » (swollen celles) and conidia in three lichenized fungi cultivated « in vitro ». — The Authors refer to the presence of « cellariola » (and « hyphycellariola ») found in pure cultures « in vitro » of the mycobiont of Xanthoria parietina and describe the morphology of conidia in the fungus isolated from Sarcogyne similis and Acarospora fuscata.

As far as the « cellariola » and « hyphycellariola » are concerned, it is the first note relative to the mycobionts of Lichens.

The Authors report the data of the utilized medium and the morphological observations.

This previous studies will be intensified by further research.     

Poly(A) polymerase in Dormant Embryos of Triticum durum

Triticum durum‘Cappelli’ has a ‘relative’dormancy which can be broken by dry after-ripening at room temperature.The breakage of dormancy in the embryos of T. durum , is accompaniedby a decline in content and a different degree of synthesisof poly(A)⁺RNA. This work studies the activity of poly(A) polymerase(E.C. 2.7.7.19), the enzyme which permits polyadenylation. Anincrease in the activity of this enzyme in parallel with theenhanced rate of germination is revealed. Since poly(A) polymeraseactivity is the same in dormant and non-dormant dry embryos,it seems that the activity of the enzyme is not involved inthe breakage of dormancy. The use of cycloheximide and cordycepinshows the presence of enzymes with different origins: a storedenzyme and one bound to a long lived mRNA, present in dormantand non-dormant embryos, plus an enzyme bound to newly synthesizedmRNA which is mainly active in non-dormant embryos. Since dormancycould be the result of an interaction between hormones, thiswork analyses the effects of GA₃and ABA on poly(A) polymerase.GA₃enhanced poly(A) polymerase activity only in dormant embryoswhile ABA inhibited this activity only in non-dormant embryos.Cycloheximide applied to excised wheat embryos represses thestimulatory and inhibitory effects of GA₃and ABA, respectively.The hormone action on poly(A) polymerase activity is thus dependenton de novo protein synthesis. Results using cordycepin suggestthe presence of a stored mRNA for poly(A) polymerase, togetherwith hormonal regulation of enzyme activity at a translationallevel. Copyright 1999 Annals of Botany Company Triticum durum , wheat, dormancy breakage, poly(A) polymerase, GA₃, ABA, germination.     

Sulla Terminologia dei Processi Apomittici

Summary

The Author observing the great disagreement of the terminology usually adopted for the apomictic phenomena, examines the whole series of the phenomena noted both in regards of the formation of the gametophyte and of the embryo. The forming of the gametophyte is fixed on the base of nature of its original cell, normally a haploid spore or »haplospore« (phenomenon of the »haplospory« following the regular meiosis), rarely a diploid spore or »diplospore« (phenomenon of the »diplospory« following the irregular meiosis, as for instance in the case of restitution nucleus, etc.). The original cell can be at least represented by the same cell that usually is the spore mother cell, whether for the outward causes, or for inward causes is lacking the usual reductional process. For the failure of the meiotic process, such a cell cannot be called »spore«.

A cell of the somatic tissue of the sporophyte can even become the original cell of the gametophyte always in case of the absence of the meiosis. These two last cases of apospory are respectively called: »somatic apospory« and »gonial apospory« (= germinal apospory) (Chiarugi 1926).

The formation of the embryo is fixed on the base of the nature of the fecundation. The principal phenomena of the fecundation are represented by the following cases: »amphigamy« (or eugamy, or gamy), »semigamy, »pseudogamy«, »apogamy« »parthenogenesis«. The A. uses the term »apogamy« both for the diploid eggs and for the haploid eggs in which the stimulation of the division is produced by the pollen-tube or by male nuclei, in absence of the gamy.

The term »parthenogenesis« is restricted to the division of the haploid or diploid eggs in which the stimulation is not caused by pollen-tube nor even for the great reason, by the male nuclei existing in it.     

Comportamento Alla Germinazione Delle Cariossidi Delle Linee Primaverile e Invernale del Triticum Esaploide «Denti de Cani»

Abstract

The germination of spring and winter wheat lines of exaploid Triticum « Denti de Cani ». — The dormancy in the seeds of two lines of Triticum « Denti de Cani » (which is spontaneous in Sardinia), one with solid stem (CP line), a spring line, the other with hollow stem (CV line), an winter line, has been studied. Germination was carried out in the dark, in Petri dishes at the constant temperatures of 5°, 10°, 20°, 23°, 26°, 30° and 35°C, using full ripe seeds, and seeds in different stages of after-ripening up to one year of age. The increase in % germination, for increasing temperatures above 5°C, is clearly conditioned by the progress of after-ripening in the seeds. In fact it was seen that, in general for the two lines, percentages over 50% of seeds germinated at 3 days were reached: at 10° and 20° after 15 days from the full ripening; at 23°C after 30 days; at 26°C after 50 days; at 30°C after about 100 days and at 35°C only after about 4–5 months from the harvest. During the experiment at 5°C it was observed that, during the first year of life of seeds and especially in the CP line, this temperature produces a clear slowing down in germinations after first year from the ripening, only the CV seeds — not the CP which remain very much inhibited — reach germination values over 50% at 3 days. It has also been demonstrated that the CV are more sensitive than the CP, in the first initial period of after-ripening (15 and 30 days), to the non-inhibiting activity of low temperatures (5° and 10°C) and that, between these, the 10°C temperature promotes the germination more clearly than the 5°C temperature. The results obtained have shown that the dormancy wears off in the spring CP-line much more slowly than in the winter CV-line. The CP-seeds remain in a relative dormancy condition for a long time, which causes a significative delay in germination, up to 100 days from the full ripening stage.     

Phytotoxic, clastogenic and bioaccumulation effects of the environmental endocrine disruptor bisphenol A in various crops grown hydroponically

The effects of the endocrine disruptor bisphenol A (BPA) at concentrations of 10 and 50 mg l⁻¹ were evaluated on the germination and morphology, micronuclei (MN) content in root tip cells and BPA bioaccumulation of hydroponic seedlings of broad bean (Vicia faba L.), tomato (Lycopersicon esculentum Mill.), durum wheat (Triticum durum Desf.) and lettuce (Lactuca sativa L.) after 6 and 21 days of growth. In general, BPA at any dose used did not inhibit germination and early growth (6 days) of seedlings of the species examined, with the exception of primary root length of tomato which decreased at the higher BPA dose. In contrast, an evident phytotoxicity was induced by BPA in all species after 21 days of growth with evident morphological anomalies and significant reductions of the lengths and fresh and dry weights of shoots and roots of seedlings. With respect to the nutrient medium without seedlings, BPA concentration decreased markedly during the growth period in the presence of broad bean and tomato seedlings, and limitedly in the presence of durum wheat and, especially, lettuce. Further, the presence of BPA measured in roots and shoots of broad bean and tomato after 21-day growth indicated that bioaccumulation of BPA had occurred. The number of MN in broad bean and durum wheat root tip cells increased markedly by treatment with BPA at both concentrations, thus suggesting a potential clastogenic activity of BPA in these species.     

Seed germination and growth in Triticum I. Biological activity of extracts from T. durum endosperms

The nature of germination inhibitors in seeds of Triticum durumwas investigated. From a methanol extract of isolated endospermsof "Cappelli" wheat, two fractionations were carried out andfractions were tested for their influence on mitotic processesand growth of Triticum "Cappelli" plantlets. One of the sub-fractionsdepressed root growth, caused accumulation of metaphases, andinduced chromosome aberrations. The biological activity of thissub-fraction closely resembles that of the germinations inhibitorsof wheat seeds. ¹ This work was supported by a grant from the Consiglio Nazionaledelle Ricerche. (Received October 19, 1971; )