TY - JOUR
T1 - Evaluation of BC2 progenies derived from 3x-2x and 3x-4x crosses of Lilium hybrids
T2 - A GISH analysis
AU - Lim, Ki Byung
AU - Ramanna, M. S.
AU - Jacobsen, E.
AU - Van Tuyl, J. M.
PY - 2003/2/1
Y1 - 2003/2/1
N2 - An allotriploid (ALA, 2n=3x=36) BC1 plant was obtained by backcrossing a diploid F1 interspecific hybrid (LA, 2n=2x=24), derived from a Lilium longiflorum (L genome) and an Asiatic hybrid (A genome), to the latter parent. This allotriploid was backcrossed to a diploid Asiatic hybrid (2n=2x=24) and to an allotetraploid (LLAA, 2n=4x=48) LA hybrid. A total of 25 plants of these crosses were examined for ploidy level, and 12 individuals were analyzed for their genome constitution through genomic in situ hybridization (GISH). In most cases the progenies from the triploid-diploid (3x-2x) crosses consisted of aneuploids. Further more, there was evidence for the formation of near-haploid (x=12+2) to triploid (3x=36) gametes in the allotriploid BC1 plant. The progenies of triploid-tetraploid (3x-4x) cross also consisted of mostly aneuploids but in this case the triploid female parent had contributed predominantly near-triploid (2n) gametes for the origin of BC2 progenies. The different ploidy levels observed between 3x-2x and 3x-4x crosses are possibly caused by preferential fertilization or survival resulting in a different ratio of chromosome numbers between the embryo and endosperm. Though Lilium has a tetrasporic, eight-nucleate type of embryo sac formation (Fritillaria type), the observed difference between the progeny types in 3x-2x and 3x-4x crosses is comparable to that of observed in monosporic eight nucleate types (Polygonum type) that predominate in most genera of Angiosperms. An important feature of the genome constitution of the progenies was that the homoeologous recombinant chromosomes were transmitted intact from BC1 to BC2 progenies in variable numbers. In addition, there was evidence for the occurrence of new homoeologous recombinations in the triploid BC1. Of the two euploid BC2 plants one had originated through the parthenogenetic development of a 2n egg and the other had originated through indeterminate meiotic restitution (IMR).
AB - An allotriploid (ALA, 2n=3x=36) BC1 plant was obtained by backcrossing a diploid F1 interspecific hybrid (LA, 2n=2x=24), derived from a Lilium longiflorum (L genome) and an Asiatic hybrid (A genome), to the latter parent. This allotriploid was backcrossed to a diploid Asiatic hybrid (2n=2x=24) and to an allotetraploid (LLAA, 2n=4x=48) LA hybrid. A total of 25 plants of these crosses were examined for ploidy level, and 12 individuals were analyzed for their genome constitution through genomic in situ hybridization (GISH). In most cases the progenies from the triploid-diploid (3x-2x) crosses consisted of aneuploids. Further more, there was evidence for the formation of near-haploid (x=12+2) to triploid (3x=36) gametes in the allotriploid BC1 plant. The progenies of triploid-tetraploid (3x-4x) cross also consisted of mostly aneuploids but in this case the triploid female parent had contributed predominantly near-triploid (2n) gametes for the origin of BC2 progenies. The different ploidy levels observed between 3x-2x and 3x-4x crosses are possibly caused by preferential fertilization or survival resulting in a different ratio of chromosome numbers between the embryo and endosperm. Though Lilium has a tetrasporic, eight-nucleate type of embryo sac formation (Fritillaria type), the observed difference between the progeny types in 3x-2x and 3x-4x crosses is comparable to that of observed in monosporic eight nucleate types (Polygonum type) that predominate in most genera of Angiosperms. An important feature of the genome constitution of the progenies was that the homoeologous recombinant chromosomes were transmitted intact from BC1 to BC2 progenies in variable numbers. In addition, there was evidence for the occurrence of new homoeologous recombinations in the triploid BC1. Of the two euploid BC2 plants one had originated through the parthenogenetic development of a 2n egg and the other had originated through indeterminate meiotic restitution (IMR).
KW - Asiatic hybrids
KW - Embryo-endosperm ratio
KW - Indeterminate meiotic restitution (IMR)
KW - Interploidy cross
KW - Introgression breeding
KW - L. longiflorum
UR - http://www.scopus.com/inward/record.url?scp=0038192197&partnerID=8YFLogxK
U2 - 10.1007/s00122-002-1070-6
DO - 10.1007/s00122-002-1070-6
M3 - Article
C2 - 12589558
AN - SCOPUS:0038192197
SN - 0040-5752
VL - 106
SP - 568
EP - 574
JO - Theoretical And Applied Genetics
JF - Theoretical And Applied Genetics
IS - 3
ER -