Dynamics of biochemical and morphophysiological changes during zygotic embryogenesis in Acca sellowiana (Berg.) Burr.

Abstract

Acca sellowiana (Berg.) Burr. is a native Myrtaceae from southern Brazil and Uruguay, now the subject of a domestication and breeding program. Biotechnological tools have been used to assist in this program. The establishment of a reliable protocol of somatic embryogenesis has been pursued, with a view to capturing and fixing genetic gains. The rationale behind this work relies on the fact that deepening comprehension of the general metabolism of zygotic embryogenesis may certainly improve the protocol for somatic embryogenesis. Thus, in the present work we studied the accumulation of protein, total sugars, starch, amino acids, polyamines (PAs), IAA and ABA, in different stages of A. sellowiana zygotic embryogenesis. Starch is the predominant storage compound during zygotic embryo development. Increased synthesis of amino acids in the cotyledonary stage, mainly of asparagine, was observed throughout development. Total free PAs showed increased synthesis, whereas total conjugated PAs were mainly observed in the early developmental stages. IAA decreased and ABA increased with the progression from early to late embryogenesis. Besides providing basic information on the morphophysiological and biochemical changes of zygotic embryogenesis, the results here obtained may provide adequate strategies towards the modulation of somatic embryogenesis in this species as well as in other woody angiosperms.

Dynamics of physiological and biochemical changes during somatic embryogenesis of Acca sellowiana

“…Amino acid levels, as determined in the present study, are coincident with patterns observed in zygotic embryos at the same developmental stages (Cangahuala-Inocente et al 2009a), but at relatively lower levels. However, it should be stressed that in the case of zygotic embryos the presence of teguments and endosperm tissues may have affected the accumulation patterns of these compounds.…”

“…During A. sellowiana zygotic embryogenesis, in the collecting times corresponding to the evaluated developmental stages, the predominant amino acids were asparagine and glutamine (Cangahuala-Inocente et al 2009a). However, in the present work, the predominant amino acids in A. sellowiana somatic embryos were arginine and asparagine.…”

“…4). In the same species, cotyledonary-staged zygotic embryos collected 90 d after pollination showed the highest starch content (Pescador et al 2008;Cangahuala-Inocente et al 2009a). In somatic embryos of Medicago sativa , the high content of sugar was ascribed to the carbon source in the culture medium (Horbowicz et al 1995).…”

“…Feijoa sellowiana Berg, commonly known as Feijoa or pineapple guava, is a fruit species native to southern Brazil and northern Uruguay. It has often been employed as a model system for comparative studies of zygotic and somatic embryo development (Cangahuala-Inocente et al 2009a;. According to Vasil (2008), this model system of somatic embryogenesis can improve our understanding of cellular totipotency in higher plants.…”

“…sellowiana is considered to be a model system of SE in woody angiosperms, which are recalcitrant to this in vitro morphogenetic route (Guerra et al 2013). Comparative studies among zygotic (Cangahuala-Inocente et al 2009a) and somatic embryogenesis (Cangahuala-Inocente et al 2009b) in this species provide a better understanding on the bottlenecks underlying developmental pathways. Thus, the present work aimed to evaluate the dynamic changes in the endogenous protein content, total sugars, starch, amino acids, and PAs during somatic embryogenesis of A. sellowiana.…”