Production of Polyploids and Unreduced Gametes in Lilium auratum × L. henryi Hybrid

Abstract

Intergenomic F1 hybrids between L. auratum x L. henryi and their BC1 progeny were investigated through genomic in situ hybridization technique (GISH) to determine their potential value in lily breeding. We confirmed that F1 intergenomic hybrids possessed a set of chromosomes (x=12) from both parents and that flowers of the F1 auratum × henryi hybrid showed an intermediate morphological phenotype. Pollen size, viability and germination ability were measured through microscopic observations. F1 intergenomic hybrids produced a relevant frequency of 2n-gametes, which were successfully used to perform crosses with Oriental hybrids, resulting in the triploid Oriental Auratum Henryi (OAuH) hybrid. Twenty BC1 plants were generated by crossing between four different Oriental hybrid cultivars and F1 AuH hybrids using an in vitro embryo rescue technique, after which the genome constitution and chromosome composition were analyzed by GISH. All plants were triploid, showing 12 from female parents (diploid Oriental hybrid) and 24 from male parents (diploid F1 AuH hybrid). Overall, 16 out of 20 BC1 progeny possessed recombinant chromosomes with 1-5 crossover sites per plant. Cytological analysis of 20 BC1 plants by GISH verified that the occurrence of 2n pollen formation in all F1 AuH hybrids was derived from the FDR (first division restitution) mechanism, in which the genome composition of all BC1 plants possess 12 Oriental + 12 L. auratum + 12 L. henryi chromosomes. Allotriploids derived from the AuH hybrid were used as female for crossing with the diploid Oriental hybrid cultivar 'Sorbonne' and considerable numbers of plants (0-6.5 plants per ovary) were only obtained when female OAuH (BC1) triploids were used. Taken together, the results of this study indicate that production and analysis of F1 AuH hybrids and their progeny through sexual polyploidization can be useful for efficient creation of important horticultural traits.

Breeding of lilies and tulips—Interspecific hybridization and genetic background—

“…2014 ). Additionally, Chung et al . (2013) reported that when the BC 1 plants (OOT) derived from the cross of the Oriental × Auratum Henryi hybrids were used as the female, subsequent BC 2 progeny was obtained, whereas no BC 2 plants were obtained in the reciprocal cross.…”

“…Many intersectional hybrids producing 2 n pollen were selected and used extensively to produce BC 1 progeny in different backcross combinations to diploid cultivars (AA × OA; OA × AA; OO × OA; LA × AA; OO × LA; AA × LA; OO × OT; OT × OO and Martagon × Asiatic (MA) hybrid × AA) and to tetraploid cultivars in the combination OAOA × OA ( Barba-Gonzalez et al . 2005a , 2005b , 2006b , Chung et al . 2013 , Lim et al .…”

“…After the identification of IMR, GISH analyses more clearly identified mechanisms leading to 2 n gamete formation in the subsequent progenies of F 1 hybrids. FDR and IMR have been identified in Longiflorum × Asiatic (LA), Auratum × Henryi (AuH) and Longiflorurm × Henryi (LHe) hybrids ( Chung et al . 2013 , Lim et al .…”

“…On the other hand, meiotic polyploidization occurring in hybrid lilies highly induced intergenomic recombination, which is favorable for introgression breeding (Barba-Gonzalez et al . 2004, 2006a , 2006c , Chung et al 2013 , Khan et al 2009a , 2009b , 2010 , Lim et al 2003a , Luo et al 2012 , Xi et al 2015 , Xie et al 2010 , Zhou et al . 2008a , 2008c ).…”

Special Behavior of Homo(eo)logous Chromosomes at Meiosis and the Mechanism of Partial Female Fertility of Allotriploid Lilium ‘triumphator’ (LLO)  

“…Allotriploid lilies are a main trend of modern lily breeding. They are obtained from BC 1 progeny of distant interspeci c F1 hybrids, because such F1 hybrids can produce small amount of functional 2n gametes and nonfunctional aueploid or n gametes due to abnormal meiosis [11][12][13][14][15][16][17][18][19][20][21]. In some cases, the sterile F1 hybrids were induced to become allotetraploid using oryzalin and colchicine to restore their fertility [22], then allotriploids are obtained through 4x × 2x or 2x × 4x [19].…”