IN VITRO OF ALNOS, CUPRESSUS AND CASTANEA SPP.
It is more difficult still to obtain plants from callus by regeneration process. This goal would be very useful to have new plants from the genetic point of view taking advantage of the somaclonal variation which is a general characteristic of every type of cells, tissues and organs grown in vitro. It follows, therefore, that the genetic status of the regenerated plants via callus can be different from that of the parent type. Then, it is important to use the apical meristem culture which allows to maintain the genetic stability in all the plants (clone) obtained by this technique (micropropagation).
Moreover, the application of the in vitro methods offers to day an enormous potential for the use of the new techniques of the genetic engineering to establish improved transgenic plants.
In view of these objectives a research program has been undertaken to study the in vitro behaviour of Alnus glutinosa, Cupressus sempervirens and Castanea sativa.
In Alnus glutinosa callus has been obatained from young leaves excised from sterile buds previously cultured in the Murashige and Skoog's (MS) medium containing GA3 alone or GA3 plus BAP. The leaves were put in the same medium added of NAA plud BAP or IBA plus BAP with glucose or sucrose. In these media about the 50 % of the explants formed callus. Instead, it has not been still possible to induce callus formation from hypocoptyl or cotyledon explants.
as fa Cupressus sempervirens the culture of cotyledone, hypocotyl segments and shoot tips in presence of IBA plus BAP (MS medium) stimulated the devlopment of lateral buds or the formation of new adventitious shoots. Positive results have been obtained from seedling explants and also from young shoots excised from adult plants in regard to callus induction when placed in MS (or Schenk and Hildebrandt) medium containing 2,4-D or NAA plus BAP or Zeatin.
In Castanea sativa embryo tissues produced abundant green callus when in the culture medium (MS) was included polyvinypyrrolidone (PVP) to overcome the problem of tissue browning. Moreiver, by in vitro culture of shoot tips derived from seedlingd in MS medium with NAA plus BAP a great number of new vegetative shoots have been produced; the transfer of these shoots in the same medium containing a lower BAP concentration allowed their normal development.