Biochemical changes in Araucaria angustifolia (Araucariaceae) zygotic embryos during the storage

Abstract

Abstract:Reactive oxygen species (ROS) are present in all aerobic organisms, but the seed deterioration processes can increase its production. Oxidative stress caused by higher endogenous ROS may cause irreparable damage to cells, leading to the loss of seed viability. Considering that the enzyme superoxide dismutase (SOD) composes the first enzymatic antioxidant defense mechanism, this study aimed to evaluate zygotic embryos of Araucaria angustifolia recalcitrant seeds during storage regarding changes in SOD activity. Besides, some of the major alterations resulting from oxidative stress, e.g., lipid peroxidation and changes in proteins and DNA integrity were also measured. Approximately, 7 000 seeds were harvested from a population in Southern Brazil and stored for 180 days under laboratory (L, laboratory temperature), refrigeration (R, 5 ± 1 °C) and freezing (F, -18 ± 1 °C) conditions. The analysis of lipid peroxidation through TBARS levels, SOD activity, protein profile by electrophoretic separation, and integrity of genomic DNA were performed at 0, 60, 120, and 180 days of storage. The results revealed an increase in lipid peroxidation and SOD activity, especially during the L storage, a condition in which there was an extensive degradation of proteins. Some proteins (i.e., 45, 32, and 31 kDa) were expressed only in embryos stored under R and F conditions. No damage was observed in the nuclear DNA integrity for the evaluated period of seed storage at R and F conditions. The F samples maintained the biochemical traits of interest throughout the storage period, with the exception of the protein profile. However, such changes are limiting for the maintenance of seed viability. In conclusion, R storage can be indicated to delay the metabolic feature alterations that occur when seeds are exposed to conditions of natural ambient after harvest, extending the conservation period of A. angustifolia seeds. Rev. Biol. Trop. 63 (4): 1185-1196. Epub 2015 December 01.Key words: Brazilian pine, recalcitrant seeds, seed deterioration, oxidative stress, superoxide dismutase.Araucaria angustifolia (Bert.) O. Ktze is a native conifer species from the Atlantic Rain Forest (Veloso, Rangel Filho, & Lima, 1991) in South Brazil. In its area of natural occurrence this species is one of the most important trees in ecological, economic, and social aspects (Auler, Reis, Guerra, & Nodari, 2002;Vibrans et al., 2011; Rosenfield & Souza, 2013). Among the trees of tropical origin, many species produce recalcitrant seeds, such as some of the Araucariaceae family (Song, Berjak, Pammenter, Ntuli, & Fu, 2003), including A. angustifolia (Balbuena et al., 2011 FariasSoares, Burrieza, Steiner, & Guerra, 2013), which rapidly germinate after dispersion (Löwe & Dillenburg, 2011).Seeds reach their maximum physiological quality after the completion of reserve substances allocation at physiological maturity time. From this point, the deterioration process begins, when several metabolic changes are apparent. But in recalcitrant seeds there is a patter...

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.…”

“…The first important characteristic of seeds of these species of Eugenia, apparently rare in nature, is the ability to germinate and produce seedlings even when more than half of their reserve tissue is removed (Silva et al, 2003;Delgado et al, 2010;Prataviera et al, 2015). This ability may be related to a co-evolution with predatory insects since seeds with more than half of the cotyledons consumed by insect larvae are frequently found (Côrtes et al, 2009;Silva and Pinheiro, 2009;Teixeira and Barbedo, 2012;Gaggeti et al, 2016). Therefore, reserves are produced in quantities much higher than those required for producing new plantlets.…”

Proteomic analysis of black poplar (Populus nigra L.) seed storability

“…For Araucaria angustifolia (Bertol.) Kuntze, SOD activity was low in seeds exposed to 5 and − 18°C, although at unfavourable room temperatures SOD activity initially increased but afterwards fell (Garcia et al 2015). Initial increasing in SOD activity in the ageing seeds was associated with the accumulation of H 2 O 2 (Sahu et al 2017a), which was not sufficient for the recovery, and probably with seed deterioration progress SOD was degraded, as is also suggested for black poplar seed Cu-Zn SOD.…”

LIPID, PROTEIN AND CARBOHYDRATE DURING SEED DEVELOPMENT IN Araucaria angustifólia

“…Protein was extracted following Garcia et al (2015). Extraction buffer composed of 20 mM dibasic sodium phosphate (pH 7.5), 1 mM EDTA, 50 mM NaCl, 10% glycerol (v/v), 1 mM PMSF and 1.5% β-mercaptoethanol (v/v) was added to 100 mg samples of dry matter.…”

“…Zygotic embryo development of A. angustifolia has been extensively studied (ASTARITA et al, 2003;BALBUENA et al, 2009BALBUENA et al, , 2011ELBL et al, 2015ELBL et al, , 2015FARIAS-SOARES et al, 2013;GARCIA et al, 2015;NAVARRO et al, 2017;OLIVEIRA et al, 2017;ROGGE-RENNER et al, 2013;SILVEIRA et al, 2008). These studies focused on the morphological characteristics of the embryo, which mature in April in southern Brazil.…”