1,721,008 research outputs found
L'arboricoltura nella filiera del legno pregiato
No full textL’arboricoltura realizzata con latifoglie a legname pregiato ha cominciato a diffondersi nelle campagne italiane dai primi anni “80 del secolo scorso, con le note ed alterne vicende legate al mutare dei finanziamenti pubblici e delle conoscenze tecniche disponibili. Oggi, dopo circa 25 anni dagli inizi, il ruolo di questo tipo d’arboricoltura da legno nella gestione agroambientale del territorio rurale si è certamente consolidato. D’altra parte però, il suo futuro appare sempre più legato alla capacità di soddisfare gli elevati standard qualitativi e quantitativi richiesti dall’industria utilizzatrice riducendo, nel contempo, la dipendenza dal finanziamento pubblico. Proprio questo è lo spirito che ha animato il Convegno “L’arboricoltura nella filiera del legno pregiato” organizzato dal DiProVe dell’Università di Milano nell’ottobre 2006, il quale ha perseguito due principali obiettivi: a) fare il punto sulle più recenti attività sperimentali promosse a livello internazionale, nazionale e locale per ottimizzare gli output produttivi ed ambientali di questi impianti; b) confrontarsi con le esigenze dell’industria nell’intento di individuare le sinergie di filiera più utili e costruttive per dare sbocchi di mercato al legno di pregio di produzione nazionale. In quest’ottica le presentazioni proposte al convegno e raccolte nel presente volume rendono conto sia del qualificato lavoro di studio e di ricerca compiuto in Italia su questo argomento anche nell’ambito di progetti internazionali, sia dei diversi comparti industriali ed artigianali, di ampia diffusione o di “nicchia”, interessati all’utilizzo di questa materia prima. Tra le tendenze innovative si cita la diversificazione dell’offerta produttiva con l’impiego di nuove specie e/o la valorizzazione di assortimenti non tradizionali, il che può ben corrispondere ad una domanda potenzialmente molteplice e differenziata. Si cita, ancora, l’opportunità di pervenire all’ecocertificazione del legname derivato dagli impianti di latifoglie nobili per favorirne la penetrazione sui mercati, nonché la sperimentazione di modelli colturali multifunzionali, sempre più coerenti con i principi di salvaguardia ambientale. Il quadro complessivo delineato dal presente volume è quindi assai dinamico ed in deciso progresso rispetto ad un pur recente passato. Pertanto, al fine di cogliere le opportunità che si prospettano, è oggi prioritario ed urgente proseguire le attività di ricerca e sviluppo in maniera sempre più mirata e coinvolgendo tutti gli attori della filiera
Organogenesi e aspetti della coltura in vitro di cultivar di ciliegio dolce
No full textSweet cherry cv“Hedelfinger” e “Burlat C1” showed different responses to ‘in vitro’ culture conditions. Shoot regeneration of “Hedelfinger”occurred, after several months, from wounded leaflets cultured on TDZ and IAA. Red light enhanced elongation of “Hedelfinger” and somaclon “HS” shoots and affected proliferation of somaclon “HS”
Modification of fruit tree architecture by biotechnology approaches
No full textItaly produces high quantity of fruit whose major part is exported in other countries. Other countries invest a large amount of their economical resources into the area of genetic improvement and plant development study. In many cases plant growers and farmers of our country must pay royalties to other countries for plant breeding technologies, for using improved cultivars. Nonetheless, these cultivars are not always adapt to our needs and environmental conditions. Cherries and apricots are of great economic interest both for areas of high intensity investments and for marginal ones, these have problems linked with strong apical dominance (cherry, and in some cases apricot), impeding the cultivation of modern fruit production technologies, problems linked with flowering period, with fruit ripening, with problems of self-incompatibility and cold tolerance.
The objective of this research, which involves seven Research Units from several Italian public labs, is to improve the knowledge about growth and development of fruit crops, through the studies of two important factors such as light and plant growth regulators and their interactions. In this context biotechnologies are used for two main reasons: the first one is to evaluate their possible use as a method of genetic improvement and the second is to understand how light and hormones act and integrate in order to determine the development and architecture of the plant.
Plant photoreceptors are involved in light dependent responses. Overexpression of phytocrome a and b (belonging to the multigene family encoding phytocrome) has been demonstrated to induce phenotipic consequences such as short hypocotyl in transgenic Arabidopsis seedlings (Wagner, 1991) and reduction of apical dominance in transgenic fruit trees (Muleo e Iacona,1998). The genes that we are going to use for plant transformation are phytochrome A (phyA) of rice, phytochrome B (phyB) of Arabidopsis thaliana and the rol genes of A. rhizogenes. Both, phyA and phyB, control the biochemical signal regulating the expression of the strategy of plants development (avoidance shade syndrome), the proteins of the rol genes interact with the signal chain of the hormones which have a preponderant role in the plant development. We expect that the over expression of phytochrome genes will induce phenotypic modifications affecting apical dominance, reduced canopy development, functional and dimensional development of root system, flowering time, reduction of juvenile period. Nevertheless the use of genetic transformation requires a suitable regeneration systems. Plant regeneration from fruit tree is in most cases difficult to achieve. In spite of several reports on Prunus spp only a few literature referring to regeneration from mature tissues of Prunus avium cultivars is available (Yang et al. 1991, Hammat and Grant 1998, Negri et al. 1998). In our lab we are testing regeneration ability from mature explants of several Prunus avium cultivars and a regeneration protocol for cultivar Hedelfinger has been set up. Nevertheless Hedelfinger is demonstrated to be a recalcitrant genotype as indicated by the very poor regeneration frequencies obtained and by the fact shoot regeneration has quite a discontinuous trend. At the present time other commercially relevant cultivars, such as Lapins and Burlat C1, are now under testing to determine the conditions to induce regeneration.
Regenerated plantlets from cultured tissues can undergo somatic stable variation and meiotically heritable variation caused by the in vitro process. So, random and frequent genetic variability occurring in cell cultures is preserved among the population of regenerants. Despite this, very little is understood about how somaclonal variation can occur and be regulated, the event is particularly intriguing because it is presumably under the control of many factors. Transgenic plants are expected to integrate and express one or more foreign gene in an otherwise unmodified genomic environment. Indeed, less attention has been given for the occurrence of somaclonal variation in transgenic plants also if in some case it has been documented at the morphological and agronomic level or in other cases molecular evidence has also been given (Sala et al, 2000).
We have performed an early screening method for selection of putative somaclones based on morphological and physiological traits regulated by the light quality (Piagnani et al 2001, a) Regenerated and micropropagated shoots, were incubated for four weeks under continuous light supplied by different types of lamps, filtered through photoselective layers in order to obtain several spectral outputs. When grown under different light spectral quality one somaclone, named HS, shows a different pattern of growth and development compared to the wild type with the main modifications related to apical dominance and chlorophyll production: somaclone HS shows reduced apical dominance compared to the wild type and a different pattern of chlorophyll a and b production. Light quality has played a different role on chlorophylls content in somaclone HS in respect of cultivar H. In particular blue light significantly promoted Chl a + Chl b content only in somaclone HS both in vitro and in ex vitro (glasshouse) conditions (Piagnani et al 2001, b). Darkness affects Chl a + Chl b at a greater extent in HS than in H which has shown to be able to accumulate higher amounts of chlorophylls than somaclone, also in this case both in vitro and in ex vitro.
DNA analyses of HS, conducted using Inter Simple Sequence Repeat (ISSR), has revealed polymorphism between the somaclone HS and wild type propagated by microcuttings. As regarding DNA analysis of non-coding region of chloroplast DNA (trn) and mitochondrial DNA, NADreductase gene region, no differences between H and HS have been detected.
A total of 15 ISSR primers have been screened for the amplification of genomic DNA. ISSR5 primer did not amplify any DNA fragment, while amplifications profiles obtained through ISSR6 and ISSR8 primers were able to reveal polymorphism between H and HS, in which, respectively, 2 fragments of about 830 and 760 bp are present in HS, and 2 fragments of about 1430 and 1080 bp are present in H. Out of a total number of 80 analysed fragments 4 were polymorphic.
References
Hammatt, N., Blake, P.S., Hand, P., 1998. Characterisation and use of apparent rejuvenation achieved during micropropagation of mature Prunus avium L. In : Davey MR, Alderon PG, Lowe KC and Power JB (eds) Tree Biotechnology: towards the millennium. Pp 45-63. Nottingham University Press, Nottingham.
Muleo e Iacona,1998. [regolazione dell’habitus vegetativo da parte del citocromo, evidenze fenotipiche in piante di ciliegio sovraesponenti il citocromo A di riso]. Atti AGRO-BIO-FRUT, incontro tecnico su “La trasformazione genetica delle piante da frutto: stato d’avanzamento delle ricerche in atto”. Cesena, 8 maggio, pp 14-15. [In Ital.]
Negri, P., Magnanini, E., Cantoni, L., Berardi, G., Sansavini, S. [Piante arboree transgeniche: prime esperienze sul trasferimento di geni per il controllo dell’habitus vegetativo]. Rivista di Frutticoltura 5: 91-97, 1998.[In Ital.]
Piagnani C., 1998. [Organogenesi e aspetti della la coltura in vitro di cultivar di ciliegio dolce. Atti AGRO-BIO-FRUT, incontro tecnico su “La trasformazione genetica delle piante da frutto: stato d’avanzamento delle ricerche in atto”]. Cesena, 8 maggio, 1998, 12-13. [In Ital.]
Piagnani C., Iacona C., Intrieri M. C., Muleo R., 2001, a . A new somaclone of Prunus avium shows diverse growth pattern under different spectral quality of radiation. Biologia Plantarum, accepted May 10 2001
Piagnani C.,. Iacona C,. Intrieri M. C, and Muleo R. 2001. b A Somaclonal variant in 'Hedelfinger' sweet cherry. Proc. ISHS IV Int. Cherry Symp, Oregon-Washington USA, in press
Sala F., Arencibia A., Castiglione S., Yifan H., Labra M., Savini C., Bracale M. and Pelucchi N., 2000. Somaclonal variation in transgenic plants. Proc. of the ISHS Int. Symp.on Methods and Markers for Quality assurance in Micropropagation. Acta Hortic 530, 411- 419
Taiz and Zeiger, 1996. Fitocromo e fotomorfogenesi. In: Fisiologia vegetale, Piccin S.p.a, Padova.
Tucker,1976. Effects of far-red light on the hormonal control of side shoot growth in the tomato. Ann. Bot. 40:1033-1042
Wanger D. Tepperman J.M. and Quail H.P., 1991 Overexpression of Phytochrome B induces a short hypocotil phenotype in transgenic Arabidopsis. The Plant Cell, 3: 1275-1288
Yang H. Y., Schmidt H., Kett U. 1991. Adventitious shoot regeneration in vitro in cherries. I. Adventitious shoot formation from in vitro-cultured leaves of the cherry rootstock '209/1'. - Gartenbauwissenschaft. 56: 5, 210-213,.
Assessment of regeneration and transformation in sweet cherry cultivars
Full text linkThe sheer size of the tree is still one of the most relevant cherry-growing related problems. Genetic transformation with phytochrome genes could contribute to the reduction of tree size in cherry. The responses to morphogenesis and genetic transformation were compared in two sweet cherry commercial cultivars and the characterised somaclone HS. Axenic shoot cultures of ‘Hedelfinger’, ‘Lapins’ and somaclone HS were grown on BA (6-benzylaminopurine) containing medium. The apical portion of each shoot was cultured in the presence of BA and NAA (naphthalene acetic acid) in the dark. After two weeks the callus formed at the base of each shoot, a 3-4 mm upper stem portion deprived of axillary shoots/buds and intact leaves were subcultured on regeneration medium, in the light. A. tumefaciens (C58C1 pGV3850), carrying the p35SGUSIntron binary vector was used to infect shoots deprived of unfolded leaves and lateral buds by either full immersion or basal dipping in the bacterium suspension. After 21 days under light, all tested explants, except ‘Lapins’ stems, showed regeneration ability. All reached their maximum regenerative expression within 56 days and ‘Lapins’ basal callus scored the highest regeneration percentage (50.1%). Basal dipping was chosen as the optimal system to infect the two cultivars and the somaclone which showed a different attitude to produce morphogenic callus. The morphogenic masses kept growing on 50 mg L-1 kanamicine for 40 weeks and the first shoots started to elongate when the BA was reduced by one-fourth. GUS activity was found in the shoot basal cuts and surrounding tissues and this evidence let us deduce that hypothetically transformed cells had chances to take part in either direct or indirect morphogenesis
Shoot Regeneration, in Vitro Performances of Regenerated Shoots and Transient Expression in Morphogenic Explants in Prunus avium cultivar 'Burlat C1'
Full text linkBiotechnology may represent alternative ways to
genetic improvement of sweet cherry exploiting somaclonal
variation and genetic transformation. In this
paper a method to induce efficient shoot regeneration
from somatic explants of ‘Burlat C1’ is reported:
52.0 % caulogenesis was obtained from basal callus
formed after culturing shoot apical portions in the
dark. Considering the significant onset of adventitious
shoots showing variegated leaves their in vitro performances
have been evaluated as compared to green
(normal) shoots. The influence of cefotaxime, cefotaxime
plus vancomycin and timentin was assessed both
for decontamination and regeneration efficiency prior
transforming morphogenic masses with A. tumefaciens
(C58C1 pDN3514), carrying the rolABC genes from A.
rhizogenes, p35GUS-intron visible marker and nptII
antibiotic resistance gene. GUS test indicated the presence
of transient expression in shoot primordia nevertheless
it was not possible to recover transgenic shoots
probably due to the formation of chimeric meristem
La micropropagazione di Photinia x fraseri ’red robin’
No full textA successful methodology to micropropagate Photinia x fraseri 'Red Robin' has been set u
An in vitro approach to study ripening phenomena of fruits
No full textHuge fruit variability, long lasting times and big amounts of needed fruits are some drawbacks in studies of ripening physiology. The in vitro approach to this kind of problems helps to bypass many of them. This work presents two in vitro systems on tomato and apple pericarps useful to study the effects of divalent ions and heat treatments on enzyme activities and cell wall metabolism during fruit ripening. The effectiveness of both systems is compared with whole fruit response
Morfologia e fenologia
No full textLa reale provenienza geografica del pesco [Prunus persica (L.)Batsch.] e cioè l’ovest della Cina, è stata accertata in epoca relativamente recente.L’inquadramento sistematico del pesco è stata un’operazione piuttosto complessa che, nel tempo, ha visto questa specie elencata sotto generi e specie diverse
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