Somatic embryogenesis in slash pine (Pinus elliottii Engelm): improving initiation of embryogenic tissues and maturation of somatic embryos

Abstract

Slash pine (Pinus elliottii Engelm.) has strong adaptability, early growth and high turpentine yield, and it is widely planted in southern China. Breeding of disease-resistant varieties is an effective way to prevent and control development of pine needle brown spot on slash pine in China. Plant regeneration by somatic embryogenesis has been achieved for slash pine, but large-scale production of somatic embryos remains restricted by several factors. We tested different embryogenesis conditions from time of initiation to maturation and studied genetic stability at simple sequence repeat (SSR) loci of regenerated plants in slash pine. Immature zygotic embryos of four open-pollinated mother trees were used for initiation of somatic embryogenesis. Seed sources (families) had a significant impact on initiation of embryonal suspensor mass (ESM, p < 0.05); however, the addition of abscisic acid ABA (1–2 mg/L) and phytosulfokine PSK (0.5 mg/L) could effectively improve initiation rate by up to 36%. Seed family 27 was the most favorable female parent for ESM initiation. The production (number of somatic embryos) was significantly increased by adding ABA (5 mg/L) during suspension culture before transferring to maturation media (p < 0.05). We tested the genetic stability of 14 regenerated plants at SSR loci, and 88.9% plants with normal phenotypes were found not to have genetic variation. We clarified the somatic embryogenesis conditions suitable for slash pine and established somatic embryo maturation technology. We clarified the somatic embryogenesis conditions suitable for slash pine and established somatic embryo maturation technology by studying several related influencing factors.