ROOTING OF CASTANEA-SATIVA MILL SHOOTS - EFFECT OF AGROBACTERIUM-RHIZOGENES T-DNA GENES

Two Agrobacterium strains, Agrobacterium tumefaciens-ORF11 and Agrobac terium rhizogenes wild type 1855, were inoculated at the base of shoot s of Castanea sativa Mill. in an attempt to improve the rooting (numbe r and quality) of the shoots, or, later, of the cuttings. The inoculum was administered in June or in July, with or without a growth regulat or mixture (indolebutyric acid, polyvinylpyrolidone, alpha naphthol an d certain vitamins), and with or without basal etiolation. A rhizogene s 1855 was always ineffective (except for callus production); but when A. tumefaciens-ORF11 was inoculated in June and in combination with g rowth regulator and etiolation, rapid and viable rhizogenesis was indu ced on the shoots within a month. If these rooted shoots were then air layered for four months (until October) a good root system developed that allowed the plantlets to be potted immediately (rather than in th e following March after four months in a mist propagation bed, as woul d otherwise be the case) with high survival after potting. With this m ethod, the clonal propagation of adult chestnut trees becomes a practi cal possibility.