Glutathione and abscisic acid supplementation influences somatic embryo maturation and hormone endogenous levels during somatic embryogenesis in Podocarpus lambertii Klotzsch ex Endl.

Abstract

Here we propose a protocol for embryogenic cultures induction, proliferation and maturation for the Brazilian conifer Podocarpus lambertii, and investigated the effect of abscisic acid (ABA) and glutathione (GSH) supplementation on the maturation phase. ABA, zeatin (Z) and salicylic acid (SA) endogenous levels were quantified. Number of somatic embryos obtained in ABA-supplemented treatment was significant higher than in ABA-free treatment, showing the relevance of ABA supplementation during somatic embryos maturation. Histological analysis showed the stereotyped sequence of developmental stages in conifer somatic embryos, reaching the late torpedo-staged embryo. GSH supplementation in maturation culture medium improved the somatic embryos number and morphological features. GSH 0mM and GSH 0.1mM treatments correlated with a decreased ABA endogenous level during maturation, while GSH 0.5mM treatment showed constant levels. All treatments resulted in decreased Z endogenous levels, supporting the concept that cytokinins are important during the initial cell division but not for the later stages of embryo development. The lowest SA levels found in GSH 0.5mM treatment were coincident with early embryonic development, and this treatment resulted in the highest development of somatic embryos. Thus, a correlation between lower SA levels and improved somatic embryo formation can be hypothesized.

Effects of genotypes and explants on garlic callus production and endogenous hormones

“…This is supported by the results of Quiroz-Figueroa et al 46 , who suggested that a low SA concentration can induce the reprogramming of somatic cells, forcing them into the embryogenic stage, while at a high concentration this reprogramming may be inhibited. This confirmed the correlation between a lower endogenous SA concentration and improved callus induction 47 . Although most previous studies only focused on the hormone levels in the calli produced by tissue culturing, it is evident that greater levels of endogenous JA, IAA and GA hormones in explants are important for garlic callus formation and proliferation.…”

Temperature and Water Availability During Maturation Affect the Cytokinins and Auxins Profile of Radiata Pine Somatic Embryos

“…Nevertheless, in peach seeds, phosphates and ribosides of the DHZ and iP-type are the predominant CKs and functions like embryo formation and growth, division of endosperm primary nucleus, endosperm cellularization and endosperm cell division have been attributed to them (Arnau et al, 1999). So, opposite to Pacheco de Freitas et al (2016) active CK levels seem to be important during the later stages of embryo development and maturation showing large amounts of these phytohormones in treatments with high production of mature embryos.…”

Female versus male: Rumex thyrsiflorus Fingerh. under in vitro conditions. Does sex influence in vitro morphogenesis?

“…Factors, which induced somatic embryogenesis, may directly or indirectly affect the auxin balance and/ or responses within the cells (Fehér 2015 and literature therein). According to Fraga et al (2016) cytokinins are also important during the initial phase of somatic embryogenesis, but not for the later stages of embryo development and maturation. The various cell-types exhibit specific responses to the same stress factor, what can explain the striking influence of the genotype, explant source, culture, and stress condition on the embryogenic capability.…”