Somatic embryogenesis and peroxidase activity of desiccation tolerant mature somatic embryos of loblolly pine

Abstract

White, translucent, glossy mucilaginous callus was initiated from the matur zygotic embryos explants on callus induction medium with 2,4-D, BA, and kinetin in the 3–9th week of culture. This type of callus induction occurred at a lower frequency with either α-naphthaleneacetic acid (NAA) or IBA (both 8 mg/L). White, translucent, glossy mucilaginous callus was embryogenic and mainly developed from the cotyledons of the mature zygotic embryo. Somatic embryos were formed on differentiation medium. Desiccation tolerance can be induced by culturing somatic embryos of loblolly pine (Pinus taeda L.) on medium supplemented with 50 μm abscisic acid (ABA) and/or 8.5% polyethylene glycol (PEG₆₀₀₀). Scanning electron microscopy of desiccated somatic embryos showed that the size and external morphology of the desiccation tolerant somatic embryos recovered to the pre-desiccation state within 24–36 h, whereas the sensitive somatic embryos did not recover and remained shriveled, after the desiccated somatic embryos had been rehydrated. Peroxidase activity of desiccated somatic embryos increased sharply after 3 days of desiccation treatment, and desiccation tolerant somatic embryos had higher peroxidase activity compared to sensitive somatic embryos. Higher peroxidase activity of desiccation tolerant somatic embryos was possibly advantage of catalyzing the reduction of H₂O₂ which was produced by drought stress, and protecting somatic embryos from oxidative damage.

Keywords

Pinus taeda L / Somatic embryogenesis / Desiccation tolerance / Peroxidase activity / CLC number / Q55 / S791.255.04 / A