Genotypic control of high-frequency adventitious shoot regeneration via somatic organogenesis in loblolly pine
Introduction
Organogenesis and somatic embryogenesis have the potential for eventual mass propagation of superior genotypes of forest trees, and for genetically engineering genotypes in both coniferous and hardwood species [1], [2]. Somatic embryogenesis and organogenesis have been induced from more than 30 tree species in conifers [3], [4], [5]. However, plant regeneration via somatic embryogenesis and organogenesis remains difficult with a low regeneration frequency for some of conifers, especially for Pinus species [3], [6], [7], [8].
Loblolly pine (Pinus taeda L.) is an economically important forest tree which is widely planted in tropical and subtropical regions. Since Mott and Amerson [9] first reported in vitro propagation of loblolly pine and Gupta and Durzan [10] first reported plant regeneration of loblolly pine via somatic embryogenesis, extensive studies have been conducted on somatic embryogenesis and somatic organogenesis in this species, and plant regeneration via somatic embryogenesis and organogenesis from callus induced from immature zygotic embryos and cotyledons has been reported [11], [12], [13], [14], [15]. However, work to improve regeneration frequency and establish a regeneration protocol suitable for most families of loblolly pine is still needed.
In the present study, we reported plant regeneration via somatic embroyogenesis using mature zygotic embryos of 24 genotypes as explants, and aimed at establishing a general protocol suitable for regeneration of most of genotypes of loblolly pine. Influence of medium, genotypes, and culture conditions on induction and differentiation of callus were evaluated. Compared to the previous work [15], in vitro regeneration of loblolly pine genotypes was extended from 3 to 27 and higher callus induction frequency and adventitious shoot differentiation frequency were obtained in this investigation.
Section snippets
Plant materials
Seeds of twenty genotypes were provided by the NC State Tree Improvement Program (TIP), and stored in plastic bags at 4°C. Mature cones of four genotypes of loblolly pine were collected in October 1998, from International Paper Company (IPC) (Georgia). All cones were stored in paper bags at 4°C before they were used for tissue culture. Seeds were disinfected by immersion in 70% w/w ethanol for 30 s and in Clorox for 10–20 min, followed by four rinses in sterile distilled water. Mature zygotic
Callus induction
Mature zygotic embryos were cultured on callus induction medium consisted of TE medium supplemented with 10 mg/l 2,4-D or NAA, 4 mg/l BA, and 4 mg/l kinetin in the dark. Mature zygotic embryos began to produce callus in the third week of culture. Callus induction frequencies, from 18.2% (genotype 11-1103) −77.7% (genotype 7-100) from mature zygotic embryos was obtained in the ninth week of culture (Table 1). As the calli started to proliferate, three types could be distinguished: 1)
Acknowledgements
Our thanks to Dr. Henry Amerson for his useful discussion and suggestion, to Kamal Chowdhury of IPC for cone collection, to program manager Suzan McCord and lab manager Reenah Schaffer for support and help, and to the NC State Tree Improvement Program for providing seeds. This work was supported by funding from the North Carolina State University Forest Biotechnology Industrial Associates.
References (23)
- et al.
Bud induction on isolated needles of Norway spruce (Picea abies L. Kast.) grown in vitro
Plant Sci. Lett.
(1979) - et al.
Somatic embryogenesis in loblolly pine (Pinus taeda L.)
- et al.
Loblolly pine (Pinus taeda L.)
- et al.
Embryogeny of gymnosperms: advances in synthetic seed technology of conifers
Plant Cell Tiss. Org. Cult.
(1993) - et al.
Application of somatic embryogenesis in high-value clonal forestry: deployment, genetic control, and stability of cryopreserved clones
In Vitro Cell Dev. Biol.
(1999) - et al.
Somatic embryogenesis in conifers
Can. J. Bot.
(1991) - et al.
De novo shoot organogenesis of Pinus eldarica Med. in vitro. 1: reproducible regeneration from long-term callus cultures
Plant Cell Rep.
(1987) - et al.
Growth and differentiation of callus cultures of Pinus
Plant Cell Rep.
(1985) - et al.
Sustained caulogenesis in callus cultures of Larix eurolepsis initiated from short shoot buds of a 12-year-old tree
Am. J. Bot.
(1988) - R.L. Mott, H.V. Amerson, A tissue culture process for the clonal production of loblolly pine plantlets. Agri Res Serv...
Biotechnology of somatic polyembryogenesis and plantlet regeneration in loblolly pine
Bio/Technology
Cited by (13)
Influence of seed provenance on the propagation of picea abies (L.) karst
2015, Advances in Horticultural ScienceDifferential success of somatic embryogenesis in random gene pool of Norway spruce
2007, Journal of Forest Science