Partner und Internationale Organisationen
(Englisch)
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A, B, BG, CY, CZ, FIN, F, D, GR, H, IRL, I, IL, L, NL, N, PL, P, RO, SK, E, S, CH, GB
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Abstract
(Englisch)
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One of the problems that has affected tissue culture over the years is the rejuvenation one. The term rejuvenation can be defined as the partial reappearance of juvenile characteristics as opposed to reinvigoration which refers to the increase in growth rate after tissue culture (Joyce 2002). Adult tissues can become morphologically rejuvenated in vitro, that is, vitro plants develop some juvenile characters such as smaller leaf size or increased capacity for adventitious root formation (George 1993). Shoot explants from mature woody plants may undergo progressive rejuvenation with serial subculturing (Durzan 1990). In manipulating the carbon nutrition during the in vitro culture of vitis vinifera microplants by sucrose addition and/or CO2 enrichement we have obtained a variety of morphologies. Some of these vitromorphs have definite adilt characters (stem sturdiness, tendrils) whilst others show more juvenile traits (small plants, absence of tendrils). In general, the adult looking morphologies were generated by treatments that included sucrose in the medium and/or where the environment was enriched with 1200 ppm CO2. The juvenile morphologies on the other hand were produced in treatments with no sucrose and/or in confined atmospheres (where the tubes were sealed with three rounds of parafilm). These results implicate the need to focus research on the quality of micropropagation produced plants. Research in this field is usually focused on the occurrence of genetic variation in tissue cultured plants (somaclonal variation), however nodal culture, which is considered to be a stable cloning strategy, gives rise here to another type of variation (epigenetic, phenotypic or physiological) which also needs to be researched and understood. The objectives of this work are firstly to characterise the in vitro morphologies and asses microplant ontogenic state using physical criteria such as plant height, internode and tendril number. Secondly we evaluated the ABA content of the different morphologies using gc-ms, and defined if this could be a good physiological marker of juvenility for in vitro plants. Finally we evaluated the level of methylation (% methylated cytosine) in the same plant material and analysed the correlation with the other criteria.
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