Simplified and improved somatic embryogenesis of hybrid larches (Larix × eurolepis and Larix × marschlinsii). Perspectives for breeding

Abstract

• Development of clonal propagation method, such as somatic embryogenesis, has numerous applications such as mass-production of genetically improved plants and the amenability of embryogenic cultures to cryogenic storage. Since the 90’s, researchers at INRA have engaged in research on somatic embryogenesis in Larix species (Larix × eurolepis, Larix × marschlinsii). • The aim of this work was to improve and to simplify all steps of somatic embryogenesis and to apply this protocol to the new hybrid variety REVE-VERT. • The somatic embryogenesis initiation frequency from immature zygotic embryos was high (65%) on a medium with reduced plant growth regulator concentrations (2.2 µ Mo f 2.4-dichlorophenoxyacetic acid and 2.3µM of 6-benzyladenine). Simplified cryopreservation method (no need of programmable freezer) of the embryonal masses resulted in 100% recovery of cryopreserved lines. Maturation of a large number of somatic embryos was greatly improved when embryonal masses were dispersed on filter paper placed on medium containing high concentration of gellan gum (8 g·L −1 ). Under these conditions, 94% of the lines matured somatic embryos that developed into plantlets. Clearly ageing and cryopreservation did not reduce embryogenic potential of embryonal masses. • Requirements for the effective integration of somatic embryogenesis into the larch breeding programme are discussed.