Stress Influences Seed Germination in Mucilage‐Producing Chia

Abstract

Chia (Salvia hispanica L.) is an oil seed crop, with a high ω‐3 fatty acid and fiber content, used for food and medicine. Upon imbibition, seeds (nutlets) exude a pectinaceous mucilage. The impact of mucilage on seed germination under different environments is unknown. The objectives of this study were to investigate the potential impact of mucilage on chia seeds germinated under conditions of biotic and abiotic stress. Chia seeds were germinated with or without mucilage under various stress conditions in lab and greenhouse studies. Germination conditions included exposure to water, cold, heat, salt stress, and fungal infection. The mucilage was removed following hydration with an acid wash without impacting germination. There was no difference in final germination percentage of seeds with or without mucilage under optimal lab conditions. However, seeds with mucilage removed germinated more slowly, with 63% germination after 26 h compared with 97% in seeds producing mucilage. Seed germination on polyethylene glycol solutions with increasingly negative water potentials was reduced in seeds without mucilage. Seeds with mucilage production that were exposed to cycles of wetting and drying germinated better and faster than non‐mucilage‐containing seeds. Greenhouse emergence showed a similar trend, with mucilage‐producing seeds having greater emergence at lower substrate moisture levels. Under saline conditions, mucilage‐producing seeds germinated 48% higher than non‐mucilage‐producing seeds at 200 mM NaCl. The data suggest that seed mucilage production may impart an ecological advantage in arid or semiarid habitats with irregular soil moisture or soils with high salt levels.

Mucilage‐bound sand reduces seed predation by ants but not by reducing apparency: a field test of 53 plant species

“…Seed mucilage is a strikingly widespread trait across plants, occurring in over 200 genera, 100 families, and 30 orders, indicating numerous independent, convergent, evolutionary gains (Grubert 1974, Yang et al 2012. The mucilage, arising from different diaspore tissues in different plants, is hypothesized to serve many ecological roles including dispersal (epizoochory, sticking to animals), non-dispersal (anti-telochory, sticking to the ground), maintenance of dormancy, facilitation or inhibition of germination (especially in stressful conditions), and defense against pathogens and granivores (reviewed in Grubert 1974, Ryding 2001, Kreitschitz 2009, Western 2012, Yang et al 2012, Phan and Burton 2018, see also Geneve et al 2017). The mucilage, arising from different diaspore tissues in different plants, is hypothesized to serve many ecological roles including dispersal (epizoochory, sticking to animals), non-dispersal (anti-telochory, sticking to the ground), maintenance of dormancy, facilitation or inhibition of germination (especially in stressful conditions), and defense against pathogens and granivores (reviewed in Grubert 1974, Ryding 2001, Kreitschitz 2009, Western 2012, Yang et al 2012, Phan and Burton 2018, see also Geneve et al 2017).…”

“…While much is known about the composition, development, location, and underlying genetic mechanisms of mucilage production in a few select systems (e.g., Arabidopsis), fewer studies have examined the role of mucilage in ecological interactions in the field (Fuller and Hay 1983, Gutterman and Shem-Tov 1997, Engelbrecht and Garc ıa-Fayos 2012, Yang et al 2013, Engelbrecht et al 2014. The mucilage, arising from different diaspore tissues in different plants, is hypothesized to serve many ecological roles including dispersal (epizoochory, sticking to animals), non-dispersal (anti-telochory, sticking to the ground), maintenance of dormancy, facilitation or inhibition of germination (especially in stressful conditions), and defense against pathogens and granivores (reviewed in Grubert 1974, Ryding 2001, Kreitschitz 2009, Western 2012, Yang et al 2012, Phan and Burton 2018, see also Geneve et al 2017). Many seeds are consumed by predators and any defensive functions of seed mucilage have only been tested in a small number of species.…”

Moisture regime during the germination of chia seeds (Salvia hispanica L.)

“…Также существует критическое значение водного потенциала, ниже которого прорастание семян не происходит [15]. Одной из особенностей семян чиа является способность производить значительное количество слизи при гидратации, которая полностью окутывает семя, что также нужно учитывать при проращивании [16].…”

Seed mucilage evolution: diverse molecular mechanisms generate versatile ecological functions for particular environments

“…ForS. hispanica , the intact myxocarpic achenes germinates clearly better than the achenes without mucilage (Geneve et al 2017). Interestingly, SM-dependent better germination phenotypes are obtained with PEG application and not with salt at equal osmotic potential (Geneve et al 2017).…”

“…Mucilage accumulates in the outer pericarp epidermal cells during seed development. After extrusion, the mucilage remains indirectly attached to the seed via the inner pericarp-seed tegument contact (Geneve, Hildebrand, Phillips, Al-Amery & Kester 2017). Finally, additional peculiarity may exist since in Medicago truncatula and M. orbicularis , the cell wall of the endosperm forms a mucilage gel between the seed coat and the embryo (Song et al 2017).…”