Metabolic profile of Brazilian pine embryos and megagametophyte of stored seeds

Abstract

Changes in availability of metabolites during seed deterioration might damage processes of synthesis and energy release for embryonic growth. This research aimed to determine which alterations occur in metabolic profile over storage of Araucaria angustifolia seeds and how these alterations are related to viability loss. Metabolic profile of samples stored at 60, 120, and 180 days, at ambient temperature, refrigerator (5°C), and freezer (-18°C), was analyzed by Fourier transform mid infrared (FTIR) spectroscopy. Additionally, soluble proteins of embryos and soluble carbohydrates and starch of megagametophytes were also quantified and related to dry matter and seed germination. Presence of primary and secondary metabolism compounds was identified in embryos (starch, proteins, lipids and phenolic). Both embryos and megagametophytes are composed principally of carbohydrate and starch. At 180 days of storage, only freezer-stored samples maintained a metabolic profile similar to freshly harvested samples, but seed viability was dramatically reduced. Storage in refrigerator can be an alternative to control the catabolism of reserve compounds in A. angustifolia seeds, retaining about 70% germination.

A new approach towards the so-called recalcitrant seeds

“…Among the groups that persist in the area, the panel that was demonstrated up to two decades ago did not change much afterward (Figure 1). The majority of the studies are basically focused on desiccation tolerance Corsato et al, 2012;Chapell et al, 2015;Amoedo and Ferraz, 2017;Gasparin et al, 2017;Subbiah et al, 2017;Chandra and Keshavkant, 2018;Plitta-Michalak et al, 2018), identification of storage behavior (Comin et al, 2014;Joshi et al, 2015;Vicente et al, 2016; 2017; Plitta-Michalak et al, 2018), analysis of deterioration and evaluation of techniques to extend the storage period (Barbedo and Cicero, 2000;Andréo et al, 2006;Bonjovani and Barbedo, 2008;Ballesteros et al, 2014;Lan et al, 2014;Parkhey et al, 2014;Garcia et al, 2015;Ming-Yue et al, 2015;Umarani et al, 2015;Araldi et al, 2016;Hossel et al, 2016;Félix et al, 2017), and rare studying other aspects such as seed maturation (Avila et al, 2009;Lamarca et al, 2013b;Mata et al, 2013;Schultz et al, 2014;Araldi and Coelho, 2015;Shibata and Coelho, 2016;Souza et al, 2018a, b), whose importance will be discussed later, and ecological (Ramlall et al, 2015;Vaz et al, 2016;Porto et al, 2018) or germinative aspects (Moothoo-Padayachie et al, 2016). An analysis, albeit superficial, of studies developed in Brazil and in the world shows small differences.…”

Reserve metabolism of stored and germinated Araucaria angustifolia seeds

“…Starch and protein have been considered the most important reserve compounds in mature seeds of A. angustifolia (Panza, Láinez, Maroder, Prego, & Maldonado, 2002;Balbuena et al, 2011;Araldi, Coelho, & Maraschin, 2016). Starch corresponds to 73% of the megagametophyte tissue, with soluble protein representing 1 to 2.5% of the embryo and 0.3 to 2% of the megagametophyte, and insoluble protein representing 0.8% of the embryo and 0.5% of the megagametophyte (Piriz Carrillo, Chaves, Fassola, & Mugridge, 2003;Astarita, Floh, & Handro, 2004, Silveira et al, 2008, Balbuena et al, 2009Garcia, Shibata, Coelho, Soares, & Guerra, 2012;Araldi et al, 2016b).…”