Effects of pre‐ and post‐dispersal temperature on primary and secondary dormancy dynamics in contrasting genotypes of Arabidopsis thaliana (Brassicaceae)

Abstract

Germination is determined by the depth of primary dormancy and the dynamics of secondary dormancy induction. We assess how dark imbibition at cool temperatures influences primary dormancy breakage and secondary dormancy induction, and how the depth of primary dormancy influences secondary dormancy induction. We manipulated primary dormancy by maturing seeds at two temperatures (‘pre‐dispersal’) known to induce different levels of primary dormancy, and by employing genotypes that differ in primary dormancy. To assess primary dormancy breakage and secondary dormancy induction, seeds of each genotype and maturation treatment were imbibed in the dark at one of four temperatures (‘post‐dispersal’) for one of three durations. Germination proportions were recorded. Seed‐maturation condition and genotype influenced the degree of primary dormancy breakage in response to dark stratification and in the optimal temperature for dormancy breakage. Secondary dormancy induction was strongest in cool‐matured seeds and seeds stratified at warmer temperatures for longer durations. These effects were consistent across genotypes. Maturation temperature influenced the expression of genetic variation for primary but not secondary dormancy, which showed little genetic variation. Seed‐maturation temperature influenced primary and secondary dormancy induction by dark imbibition, and it also influenced the expression of genetic variation for temperature‐dependent dormancy breakage. Cool seed‐maturation induced primary dormancy in a genotype‐specific manner and enhanced secondary dormancy induction. Post‐dispersal temperature also influenced primary dormancy breakage and secondary dormancy induction. The observed interactions between primary and secondary dormancy, and between pre‐ and post‐dispersal temperature, are expected to influence life‐history expression in nature.

A review of the relationship between primary and secondary dormancy, with reference to the volunteer crop weed oilseed rape (Brassica napus)

“…Likewise, Coughlan et al . () and Edwards et al . () found a positive relationship between depth of primary dormancy and depth of secondary dormancy induction among genotypes of A. thaliana and showed that temperature during seed development impacted secondary dormancy induction in A. thaliana .…”

“…Coughlan et al . () also showed that temperature during seed development had a big impact on primary dormancy and on secondary dormancy induction in A. thaliana . Environmental conditions during seed development can also change the degree of primary dormancy and secondary dormancy induction in B. napus (Finkelstein et al ., ; Haile & Shirtliffe, ; Huang et al ., ).…”

“…There are many reports that seeds of B. napus have little or no dormancy and that water stress and darkness make them light‐requiring, that is induce them into secondary dormancy (Schlink, ; Pekrun et al ., ,b; Lutman et al ., ; Weber et al ., ; Soltani et al ., , ). However, the capacity for induction of nondormant seeds into secondary dormancy is contrary to what has been shown for some other species (Symons et al ., ; Girard, ; Simpson, ; Auge et al ., ; Coughlan et al ., ; Edwards et al ., ). In this review, we (i) argue that fresh seeds of B. napus have not been shown convincingly to be completely nondormant, (ii) present a reanalysis of published and unpublished data by E. Soltani and others (Soltani et al ., ) that strongly suggests that fresh seeds of this species have some degree of primary dormancy and (iii) discuss the relevancy of our review to the management of weedy volunteer plants of B. napus .…”

Dormancy cycling: translation‐related transcripts are the main difference between dormant and non‐dormant seeds in the field

“…Seeds that do not germinate can enter the soil seed bank where secondary dormancy can be induced if seeds experience long periods of unfavourable conditions (Barazani et al , ). In seeds of genotypes with high primary dormancy levels, secondary dormancy is induced more rapidly (Coughlan et al , ). The extent to which the mechanisms underlying primary dormancy also regulate secondary dormancy is unclear, although some of the mechanisms do overlap.…”

Maternal vernalization and vernalization‐pathway genes influence progeny seed germination

“…Such 'maternal environmental effects' are well documented in plants (Gutterman, 1982;Donohue & Schmitt, 1998;Donohue, 2009). For instance, in Arabidopsis thaliana, low temperatures experienced before or during seed maturation reduce germination propensity, alter seed responses to chilling and water availability during imbibition, and reduce seed longevity, demonstrating that environmental conditions experienced at one life stage can influence subsequent developmental transitions (Kendall & Penfield, 2012;Penfield & Springthorpe, 2012;Chen et al, 2014;He et al, 2014;Auge et al, 2015;Burghardt et al, 2015;MacGregor et al, 2015;Coughlan et al, 2016;Edwards et al, 2016). These effects of temperature also persist as seeds after-ripen (lose primary dormancy over time) and undergo dormancy cycling (Auge et al, 2015;Burghardt et al, 2015;Edwards et al, 2016).…”