Line design

A method for genetically modifying the genome of a hybrid plant by replacing one or more of its chromosomes or chromosome fragments with the corresponding chromosome or chromosome fragment of one or more donor parents, comprising:

• a) crossing one of the parents of the hybrid plant with one of the donor parents, to obtain a first F1 population, allowing the F1 to produce spores while suppressing recombination, producing doubled haploids of the spores, to obtain a first population of chromosome substitution lines,
• b) optionally crossing the other parent of the hybrid plant with the same or another donor parent, to obtain a second F1 population, allowing the F1 to produce spores while suppressing recombination, producing doubled haploids of the spores, to obtain a second population of chromosome substitution lines, and
• either:
• c1) producing a modified hybrid plant that has acquired one or more intact chromosomes of the donor parent(s), by selecting one individual of the first or the second population and crossing this individual with an individual of the other population or with a parent of the hybrid plant;
• or
• c2) producing a population of modified hybrids by:
• i. selecting one individual of the first or the second population and crossing this individual with the corresponding parent of the hybrid plant, and
• ii. allowing the progeny plant(s) resulting from this cross to produce spores, while allowing recombination to take place, to obtain a population of spores that have received one or more chromosome fragments of the donor parent, and making doubled haploids thereof, and
• iii. crossing the doubled haploid plants thus obtained with the other parent of the hybrid that is optionally modified, or with another homozygous line.