Abstract: The invention relates to DNA fragments encoding an Abi-type mechanism of resistance to bacteriophages, which fragments are capable of being obtained by cloning of chromosomal or plasmid DNA of a bacteriophage-resistant lactic acid bacterial strain, as well as to a polypeptide involved in an Abi-type resistance mechanism, encoded by one of the said fragments. The invention also encompasses recombinant vectors and transformed bacterial strains comprising the said DNA fragments.

Abstract: Starting from a herbaceous cutting, which may be derived from in vitro culture, of stock and of a herbaceous scion, the process consists of inserting the scion (12') having a single bud, into the stock cutting (12), by bevelling the lower end 15 of the scion 12' from two sides 17, 18, by slitting the upper end of the stock cutting in its middle, and by subsequently assembling the two parts 12, 12' by joining 20, of transferring the base of the abovementioned grafted unit into a development medium 21, of moistening the development medium 21 with a nutrient solution and of subsequently placing this unit in a container with a water-saturated atmosphere and at a temperature above 20.degree. C., while suppressing the bud 22 of the stock and growing the saplings in the greenhouse or under a polyethylene tunnel until the desired stage of growth.