In Vitro Tetraploid Induction from Leaf and Petiole Explants of Hybrid Sweetgum (Liquidambar styraciflua × Liquidambar formosana)

Abstract

Abstract:Liquidambar is an important forestry species used to generate many commercial wood products, such as plywood. Inducing artificial polyploidy is an effective method to encourage genetic enhancements in forestry breeding. This report presents the first in vitro protocol for the induction of genus Liquidambar tetraploids based on the established in vitro regeneration system of hybrid sweetgum (Liquidambar styraciflua × Liquidambar formosana). The leaves and petioles from three genotypes were pre-cultured in woody plant medium (WPM) supplemented with 0.1 mg/L thidiazuron (TDZ), 0.8 mg/L benzyladenine (BA), and 0.1 mg/L α-naphthalene acetic acid (NAA) for a variable number of days (4, 6 or 8 days), and exposed to varying concentrations of colchicine (120, 160, 200 mg/L) for 3, 4 or 5 days; the four factors were investigated using an orthogonal experimental design. Adventitious shoots were rooted in 1/2 WPM medium supplemented with 2.0 mg/L indole butyric acid (IBA) and 0.1 mg/L NAA. The ploidy level was assessed using flow cytometry and chromosome counting. Four tetraploids and nine mixoploids were obtained from the leaves. Pre-treatment of the leaves for 8 days and exposure to 200 mg/L colchicine for 3 days led to the most efficient tetraploid induction. Producing 11 tetraploids and five mixoploids from petioles, the best tetraploid induction treatment for petioles was almost the same as that with the leaves, except that pre-culturing was required for only 6 days. In total, 15 tetraploids were obtained with these treatments. This study described a technique for the induction of tetraploid sweetgum from the leaves or petioles of parental material. Based on the success of polyploid breeding in other tree species, the production of hybrid sweetgum allotetraploids constitutes a promising strategy for the promotion of future forestry breeding.

In vitro induction and characterisation of tetraploid drumstick tree (Moringa oleifera Lam.)

“…The leaves of drumstick tree proved to be very sensitive to colchicine exposure, and prominent cytotoxic effects were observed after the treatment. The survival and regeneration rates decreased substantially with increasing concentration and exposure time ( Tables 1 and 2 ), similar to the results of Hannweg et al [ 25 ] and Zhang et al [ 10 ]. Moreover, the survival and regeneration rates were affected more by exposure time than by colchicine concentration ( Tables 1 and 2 ).…”

“…Exposure time had the greatest effect on the tetraploid induction rate, possibly due to the lower survival rate of explants after overexposure to colchicine. Chimera induction always accompanies tetraploid induction and has been reported in many species, such as Echinacea purpurea [ 21 ], Liquidambar styraciflua [ 10 ], Dendrobium officinale [ 26 ], and so on.…”

“…Therefore, induction of polyploidy is a useful strategy for crop improvement. Among many available induction methods, colchicine application has been adopted successfully to double the chromosome number in many species [ 8 , 9 , 10 ].…”

Development and Characterization of Simple Sequence Repeat Markers for, and Genetic Diversity Analysis of Liquidambar formosana

“…During primer screening, two individuals of L. formosana were randomly selected to detect amplification, and eight were used to detect EST-SSR polymorphisms. To test cross-species transferability, six L. styraciflua were collected from Shanghai Chenshan Botanical Garden (Songjiang District, Shanghai, China, 31 • 03 N, 121 • 22 E); 13 hybrid sweetgum (L. styraciflua × L. formosana) obtained via hybridization [28] were used to test SSR transferability. The L. formosana and L. styraciflua were native population while hybrid sweetgum was from cultivated population.…”

Comparative Transcriptomic, Anatomical and Phytohormone Analyses Provide New Insights Into Hormone-Mediated Tetraploid Dwarfing in Hybrid Sweetgum (Liquidambar styraciflua × L. formosana)

“…For allotetraploid species, the advantages of some traits have been linked to heterosis ( Fuentes et al, 2014 ). Tetraploid hybrid sweetgum ( L. styraciflua × L. formosana ; Zhang et al, 2017 ) has been reported to show dwarf traits (Unpublished). Some new varieties of sweetgum, such as the dwarfing cultivar ‘Gumball’, have a shrubby appearance (maximum height of 4.5 m) ( Sommer et al, 1999 ).…”