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

Abstract

One of the possible countermeasures for pollinosis caused by sugi (Cryptomeria japonica), a serious public health problem in Japan, is the use of male sterile plants (MSPs; pollen-free plants). However, the production efficiencies of MSPs raised by conventional methods are extremely poor, time consuming, and resulting in a high seedling cost. Here, we report the development of a novel technique for efficient production of MSPs, which combines marker-assisted selection (MAS) and somatic embryogenesis (SE). SE from four full sib seed families of sugi, carrying the male sterility gene MS1, was initiated using megagametophyte explants that originated from four seed collections taken at one-week intervals during the month of July 2017. Embryogenic cell lines (ECLs) were achieved in all families, with initiation rates varying from 0.6% to 59%. Somatic embryos were produced from genetic marker-selected male sterile ECLs on medium containing maltose, abscisic acid (ABA), polyethylene glycol (PEG), and activated charcoal (AC). Subsequently, high frequencies of germination and plant conversion (≥76%) were obtained on plant growth regulator-free medium. Regenerated plantlets were acclimatized successfully, and the initial growth of male sterile somatic plants was monitored in the field.

Somatic Embryogenesis Initiation in Sugi (Japanese Cedar, Cryptomeria japonica D. Don): Responses from Male-Fertile, Male-Sterile, and Polycross-Pollinated-Derived Seed Explants

“…In this context, the development of technology to produce excellent MSPs in a short period of time is one of the priority goals. At present, efficient protocols to propagate male-sterile somatic plants of sugi combine a selection of ECs with marker-assisted selection and propagation via SE has been established [ 19 ]. On the other hand, as one of the methods for labor-saving production of genetically diverse seedlings, it is conceivable to use seeds derived from polycross pollination, artificial mating using mixed pollen from multiple parents.…”

Pinus spp. Somatic Embryo Conversion under High Temperature: Effect on the Morphological and Physiological Characteristics of Plantlets

“…SE is a biotechnological tool which consists in the dedifferentiation of somatic cells and their subsequent cell re-differentiation in somatic embryos (ses), through genetic reprogramming [10]. Based on the morphogenetic response, SE is widely used to obtain large amounts of cloned material from elite material in response to an external stress stimulus [11][12][13][14][15][16][17].…”

Factors Influencing Somatic Embryo Maturation in Sugi (Japanese Cedar, Cryptomeria japonica (Thunb. ex L.f.) D. Don)

“…In this context, the application of biotechnology to produce superior male-sterile trees in a short period of time is one of our main priorities. Now, efficient protocols to propagate male-sterile somatic plants of sugi involve combining the selection of embryogenic cells (ECs) with marker-assisted selection, and propagation through SE has been established [ 9 ].…”

“…Since SE was first reported for spruce species, numerous studies on conifer trees have been reported [ 10 , 11 , 12 ]. For sugi, after the first report on plant regeneration via SE [ 13 ], more results including studies on SE initiation [ 14 , 15 , 16 , 17 , 18 ], somatic embryo maturation [ 19 , 20 , 21 , 22 ], plant conversion [ 9 , 23 ], cryopreservation [ 24 , 25 ], and plant transformation [ 26 , 27 ] were published, showing progress in optimizing SE protocols. However, detailed reports on the factors influencing somatic embryo maturation in several ECLs from different seed families of sugi have not yet been published.…”