Plant regeneration from embryogenic tissue of Pinus luchuensis Mayr, an endemic species in Ryukyu Island, Japan

Abstract

Somatic embryogenesis in Ryukyumatsu (Pinus luchuensis Mayr.), an endemic species in Ryukyu Island, Japan, was initiated from megagametophytes containing zygotic embryos on a medium supplemented with 10 µM 2,4-dichlorophenoxyacetic acid and 5 µM 6-benzylaminopurine. Embryogenic cultures were maintained and proliferated by subcultures at 2-to 3-week-intervals on the same fresh medium. e maturation of somatic embryos occurred on media containing maltose, activated charcoal, abscisic acid and polyethylene glycol. High frequencies of germination were obtained a er the post-maturation treatment of somatic embryos under conditions of high relative humidity, and around 90% of them were converted into plants. Growth of the somatic embryo-derived regenerated plants has been monitored in the eld.

Progress in Somatic Embryogenesis of Japanese Pines

“…ET induction of JPs was initiated from whole megagametophytes containing immature zygotic embryos (Maruyama et al, 2005a,b, 2007; Hosoi and Maruyama, 2012). Seeds were disinfected with 1–2% sodium hypochlorite solution for 15–20 min (Maruyama and Hosoi, 2014).…”

“…In general, the extrusion of ET occurred 2–6 weeks after culture, and the proliferation of ET became obvious after 4–8 weeks of culture when EM increased (Maruyama and Hosoi, 2014). The induction frequency on the medium supplemented with PGRs varied from 1.0 to 2.8%, with an overall average of 2.3% (Maruyama et al, 2005a,b, 2007; Hosoi and Maruyama, 2012), which was comparable with previous results for P. densiflora (up to 2.3%, Kim and Moon, 2014), P. nigra (3.1%, Salajová and Salaj, 2005), Pinus banksiana (up to 3.9%, Park et al, 2006), P. rigida × P. taeda (up to 1.1%, Kim and Moon, 2007b), and P. lambertiana (1–3%, Gupta, 1995). These results were inconsistent with the high induction rates reported for P. radiata (44–93%, Hargreaves et al, 2011), P. taeda (up to 79%, Gupta, 2014), P. strobus (54%, Finer et al, 1989), Pinus sylvestris (up to 30%, Aronen et al, 2009), and P. pinaster (up to 75%, Park et al, 2006).…”

“…Japanese black pine is also important for protection of the coastal areas, and Japanese red pine is the principal host species of the prized “matsutake mushroom” (Maruyama and Hosoi, 2016). Ryukyu pine is valued for construction of houses and furnishings (Hosoi and Maruyama, 2012). Yakutanegoyou, an over-harvested species, was traditionally used for construction of houses and canoes; this species is now endangered and has estimated numbers of living trees of 100 and 1000–1500 in the natural stands of Yakushima and Tanegashima Islands, respectively (Maruyama et al, 2007).…”

Somatic Embryogenesis and Plant Regeneration from Sugi (Japanese Cedar, Cryptomeria japonica D. Don, Cupressaceae) Seed Families by Marker Assisted Selection for the Male Sterility Allele ms1

“…This is in contrast to studies of somatic embryo maturation of Picea abies , in which PEG is reported to stimulate embryogenesis but inhibit the subsequent germination process [ 72 ]. Partial desiccation and/or cold treatments after maturation on medium containing PEG have been reported necessary to improve somatic embryo germination and conversion in a number of conifer species, including some pines [ 73 , 74 , 75 , 76 , 77 , 78 , 79 ], spruces [ 80 , 81 , 82 , 83 ], hybrid larch [ 84 ], Fraser fir [ 66 ], and Chinese fir [ 85 ].…”

Stimulation of somatic embryo growth and development in Picea spp. by polyethylene glycol

“…The positive effect of PEG on embryo maturation has been reported for many coniferous species, including Picea abies (Hudec et al, 2016), P. likiangensis (Chen et al, 2010), P. glauca (Stasolla et al, 2002;Stasolla & Yeung, 2003), and Cryptomeria japonica (Maruyama et al, 2007). Hosoi and Maruyama (2012) reported a 25-fold increase in the number of mature embryos produced in Pinus luchuensis, relative to the number of mature embryos produced in PEG-free medium when embryogenic tissue was incubated on a medium containing 15% PEG. Tret'yakova and Barsukova (2012) reported that somatic embryos of Larix sukaczewii only developed and matured on a medium supplemented with 10% PEG.…”