Zygotic and somatic embryo morphogenesis in Pinus pinaster: comparative histological and histochemical study

Abstract

We compared morphogenesis and accumulation of storage proteins and starch in Pinus pinaster Ait. zygotic embryos with those in somatic embryos grown with different carbohydrate sources. The maturation medium for somatic embryos included 80 microM abscisic acid (ABA), 9 g l(-1) gellam gum and either glucose, sucrose or maltose at 44, 88, 175 or 263 mM in the presence or absence of 6% (w/v) polyethylene glycol (PEG) 4000 MW. Maturation medium containing 44 or 88 mM of a carbohydrate source produced only one or no cotyledonary somatic embryos per 0.6 g fresh mass of culture. The addition of PEG to the basal maturation medium resulted in a low yield of cotyledonary somatic embryos that generally showed incomplete development and anatomical abnormalities such as large intercellular spaces and large vacuoles. High concentrations of maltose also induced large intercellular spaces in the somatic embryonic cells, and 263 mM sucrose produced fewer and less developed cotyledonary somatic embryos compared with 175 mM sucrose, indicating that the effect of carbohydrate source is partially osmotic. Zygotic embryos had a lower dry mass than somatic embryos at the same stage of development. Starch granules followed a similar accumulation pattern in zygotic and somatic embryos. A low starch content was found in cotyledonary zygotic embryos and in somatic embryos developed in the presence of 175 mM maltose or 263 mM glucose. In zygotic embryos and in PEG-treated somatic embryos, protein bodies appeared later and were smaller and fewer than in well-developed somatic embryos grown without PEG. We propose that storage protein concentration might be a marker of embryo quality.

IIn Vitro Selection of Four Soybean Genotypes using PEG for Drought Tolerance

“…A low plantlet conversion is also due to abnormalities of somatic embryos produced. PEG causes the reduction in yield of somatic embryos as well as causing incomplete development and anatomical abnormalities of the somatic embryos (Tereso et al, 2007). Apparently, in our results, PEG treatment as well as genotypes influenced regeneration capacity after selection.…”

“…The increasing amount of PEG added to the selective media deteriorated somatic/callus embryo. Water stress by PEG in the media reduced the number of embryogenic callus of all genotypes in this study ( only affected callus growth but also to the ability of cells in callus masses to form embriogenic cells with somatic embryo differentiation (Tereso et al, 2007). This inhibitory effects of PEG might be due to the decreased endogenous polyamines in explant tissues under PEG stress (Hemon and Sudarsono, 2010).…”

Genes and Trans-Factors Underlying Embryogenic Transition in Plant Soma-Cells

“…In Pineapple Guava ( Myrtaceae ) 4-5 day culture of cotyledons when exposed to SE induction medium, the accumulation of starch in the plastids and the differentiation of mitochondria is the most pronounced modifi cations (Canhoto et al 1996 ). During maturation, in many cases, the embryos undergo structural development and also accumulate proteinaceous and carbohydrate compounds necessary for further development (Brownfi eld et al 2007 ;Tereso et al 2007 ).…”

Endogenous Quantification of Abscisic Acid and Indole-3-Acetic Acid in Somatic and Zigotic Embryos of Nothofagus alpina (Poepp. & Endl.) Oerst

“…There are numerous morphological and biochemical similarities observed in developing somatic and ZE N (Tereso et al, 2007). Consequently, culture sequences should include a maturation promotion phase of the somatic embryos (SE) before germination to resolve differences encountered mainly between the embryonic development and maturation processes (Palada-Nicolau and Hausman, 2001).…”