Elucidation of the polyamine biosynthesis pathway during Brazilian pine (Araucaria angustifolia) seed development

Abstract

Polyamines (PAs), such as spermidine and spermine, as well as amino acids that are substrates for their biosynthesis, are known to be essential for plant development. However, little is known about the gene expression and metabolic switches associated with the ornithine/arginine and PA biosynthetic pathway during seed development in conifers. To understand these metabolic switches, the enzyme activity of arginine decarboxylase and ornithine decarboxylase, as well as the contents of PAs and amino acids were evaluated in three Araucaria angustifolia (Bertol. Kuntze) seed developmental stages in combination with expression profile analyses of genes associated with the ornithine/arginine and PA biosynthetic pathway. Twelve genes were selected for further analysis and it was shown that the expression profiles of AaADC and AaSAMDC were up-regulated during zygotic embryo development. Polyamines and amino acids were found to accumulate differently in embryos and megagametophytes, and the transition from the globular to the cotyledonary stage was marked by an increase in free and conjugated spermidine and spermine contents. Putrescine is made from arginine, which was present at low content at the late embryogenesis stage, when high content of citrulline was observed. Differences in amino acids, PAs and gene expression profiles of biosynthetic genes at specific seed stages and at each seed transition stage were investigated, providing insights into molecular and physiological aspects of conifer embryogenesis for use in future both basic and applied studies.

Carbohydrate-mediated responses during zygotic and early somatic embryogenesis in the endangered conifer, Araucaria angustifolia

“…angustifolia embryogenesis [23,24,25,26]. A notable exception is the role of carbohydrates, which has not been studied in detail, although transcriptome and proteome analyses suggest that several genes and proteins involved in carbohydrate metabolism are highly expressed during both zygotic and somatic embryo development [15,22].…”

Seed germination and early seedling survival of the invasive speciesProsopis juliflora(Fabaceae) depend on habitat and seed dispersal mode in the Caatinga dry forest

“…Successful invasions only occur when alien species can overcome external forces (Dalmazzone & Giaccaria, 2014;Li et al, 2014;Svenning et al, 2014). These factors explain why a small fraction of stands, particularly across former agricultural lands along river banks and flooding plains (Nascimento et al, 2014;Almeida et al, 2015;Santos & Diodato, 2015;Oliveira et al, 2017). Prosopis juliflora forms dense stands, apparently excluding or impelling the reestablishment of species-rich assemblages of tree and shrub species, particularly on river banks degraded by shifting cultivation and livestock overgrazing (Pegado et al, 2006;Oliveira et al, 2012;Nascimento et al, 2014).…”

Thermospermine Synthase (ACL5) and Diamine Oxidase (DAO) Expression Is Needed for Zygotic Embryogenesis and Vascular Development in Scots Pine

“…In contrast, the Arabidopsis acl5-1 spms-1 double mutant, which contains neither Spm nor T-Spm, is viable and shows no phenotypic change except for the reduced stem growth due to acl5-1 (Imai et al, 2004). In conifers PA contents and ratios followed developmental stage dependent profiles during zygotic embryogenesis (Minocha et al, 1999;Astarita et al, 2003;Vuosku et al, 2006;de Oliveira et al, 2017). Likewise, the triggering of somatic embryogenesis pathway modulated the PA metabolism at gene expression, enzyme activity, and metabolite levels (Minocha et al, 1999;Gemperlová et al, 2009;Jo et al, 2014;Salo et al, 2016).…”