Seed heteromorphy influences seed longevity in Aegilops

Abstract

The genus Aegilops belongs to the secondary gene pool of wheat and has great importance for wheat cultivar improvement. As a genus with only annual species, regeneration from seeds in Aegilops is crucial. In several species in Aegilops, spikes produce different seed morphs, both in size and germination patterns. However, little is known about the ecology of seed germination, nor about the seed longevity in this genus. Here we investigated the germination phenology of Ae. neglecta under laboratory and field conditions and assessed longevity of different seed morphs of five additional Aegilops species using controlled ageing tests. Large seeds were short-lived and germinated faster than small seeds in most of the species. Field experiments with Ae. neglecta showed that large seeds of the dimorphic pair germinated 3 months after dispersal in contrast to 14 months for smaller seeds. Differences in longevity were detected not only in dimorphic seed pairs, but also among seeds from different positions on the spike. Our results indicate that different longevities in seed morphs of Aegilops may reflect a different soil seed bank persistence, with smaller seeds able to maintain a higher viability after dispersal than larger ones, thereby spreading seedling emergence over two years. Differences of seed germination and longevities between seed morphs in Aegilops may have important implications for ex situ seed conservation and reinforce the hypothesis of a bet-hedging strategy in the germination ecology of this genus.

Seed dormancy and longevity variability of Hirschfeldia incana L. during storage

“…It is likely that deeply dormant seeds have to stay alive for longer than non-dormant seeds, hence they may show higher resistance to ageing. Consistently, studies in Aegilops neglecta showed that dormant seeds were longer lived than non-dormant seeds (Guzzon et al, 2018). Fig.…”

“…Morphological heterogeneity within a population may occur in seed size, shape or colour (Baskin and Baskin, 1998; Imbert, 2002; Matilla et al , 2005; Zaidi et al , 2010), and has been related to physiological properties, including dormancy (Duran and Retamal, 1989; Rodríguez et al , 2015), germination (Puga-Hermida et al , 2003; Mira et al , 2011b; 2017), and longevity (Kochanek et al , 2009; Niedzielski et al , 2009; Nagel and Borner, 2010). Seed characteristics may also vary within plant and even fruit (Venable, 1985; Guzzon et al , 2018).…”

Viability and vigour loss during storage of Rudbeckia mollis seeds having different mass: an intra-specific perspective

“…Loss of germination potential results from accumulated ageing damage that occurs during seed storage or applied stresses. Growing evidence indicates relationships between intra-specific seed mass variation and seed deterioration associated with high temperature and relative humidity stress (Franks et al, 2019; Genna and Pérez, 2016; Guzzon et al, 2018; Mira et al, 2019). We examined water sorption characteristics of mass-separated R. mollis seeds and then evaluated responses of each mass class to various storage and stress treatments.…”

“…Recent studies show that lower mass seeds within populations of Aegilops , Rudbeckia and Brassica expressed greater longevity than higher mass seeds following warm, humid stress (Genna and Pérez, 2016; Guzzon et al, 2018; Franks et al, 2019). To the contrary, Mira et al (2019) found greater longevity in higher mass seeds within a population of Hirschfeldia incana .…”

“…These methods are used to discern seeds with a high and low capacity for germination or seedling establishment and to generate a relative vigour index (Baalbaki et al, 2009). Vast literature exists showing how seed scientists have adapted these techniques to study seed deterioration and model potential seed longevity (Baalbaki et al, 2009 [references therein]; Probert et al, 2009; Genna and Pérez, 2016; Guzzon et al, 2018; Franks et al, 2019; Mira et al, 2019).…”