Early-flowering Scots pines through tissue culture for accelerating tree breeding

Area of Science:

• Plant Biotechnology
• Forestry Science
• Plant Physiology

Background:

• Scots pine (Pinus sylvestris) is a commercially important timber species.
• Efficient micropropagation techniques are crucial for mass propagation and breeding programs.

Purpose of the Study:

• To establish an efficient tissue culture protocol for Scots pine plantlet production.
• To investigate the influence of plant growth regulators on shoot induction and rooting.
• To assess the potential for accelerated breeding through early flowering of micropropagated plants.

Main Methods:

• Cotyledons from germinated Scots pine embryos were used as explants.
• Optimized basal medium (1/2GD) with specific plant growth regulators (BAP, NAA) was employed.
• Shoot induction and rooting phases were optimized using varying hormone concentrations and durations.
• Micropropagated plantlets were evaluated for growth habit and reproductive maturity.

Main Results:

• Optimal shoot induction was achieved with 5.0μM benzylaminopurine (BAP) and 0.05 μM naphthaleneacetic acid (NAA).
• Rooting proved challenging, with repeated NAA pulses improving success.
• Micropropagation success rates were genotype-dependent, ranging from 3 to 15 shoots per embryo.
• Some plantlets exhibited plagiotropic growth, while others flowered early (3-4 years), producing viable pollen.

Conclusions:

• A genotype-dependent tissue culture protocol for Scots pine was developed.
• Early flowering in micropropagated individuals offers potential for accelerated breeding.
• Further research is needed to overcome rooting difficulties and optimize growth habit.