Effects of germination time on seed morph ratio in a seed-dimorphic species and possible ecological significance

Yang, Fan; Baskin, Jerry M.; Baskin, Carol C.; Yang, Xuejun; Cao, Dechang; Huang, Zhenying

doi:10.1093/aob/mcu210

Cited by 32 publications

(37 citation statements)

References 44 publications

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“…Heteromorphism in plants has often been considered a mere bet-hedging strategy, emphasizing its independence from environmental conditions (Imbert, 2002). However, our data, in accordance with several other studies, demonstrate that, in some heteromorphic plant species, morph numbers and ratio show plasticity in response to certain environmental stimuli (Mandák and Pyšek, 1999;Imbert and Ronce, 2001;Sadeh et al, 2009;Lu et al, 2013b;Yang et al, 2015). Such a blend of bet hedging and plasticity should be expected to evolve when either the cue that predicts the future environment is weak or fitness is determined by predictable and unpredictable environmental factors alike (Bradford and Roff, 1993;Simons, 2011).…”

Section: Phenotypic Plasticity Of Fruit and Seed Heteromorphismsupporting

confidence: 90%

“…Several studies suggest that at least some heteromorphic species diminish this problem by means of phenotypic plasticity, defined as the ability of a genotype to produce different phenotypes when exposed to different environmental conditions (Via et al, 1995;Sultan, 2000;Pigliucci et al, 2006;Abley et al, 2016). The fruit-morph ratio of heteromorphic species may vary in response to herbivory (Imbert and Ronce, 2001), nutrient availability and plant density (Mandák and Pyšek, 1999;Sadeh et al, 2009;Lu et al, 2013a), germination time (Yang et al, 2015), and soil moisture (Lu et al, 2013a), indicating that these plants can adjust their fruit development in response to certain environmental parameters. However, so far, very little is known about the molecular determinants of heteromorphism in general and the plastic developmental modulation of this phenotype in particular.…”

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confidence: 99%

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Developmental Control and Plasticity of Fruit and Seed Dimorphism in Aethionema arabicum

et al. 2016

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Understanding how plants cope with changing habitats is a timely and important topic in plant research. Phenotypic plasticity describes the capability of a genotype to produce different phenotypes when exposed to different environmental conditions. In contrast, the constant production of a set of distinct phenotypes by one genotype mediates bet hedging, a strategy that reduces the temporal variance in fitness at the expense of a lowered arithmetic mean fitness. Both phenomena are thought to represent important adaptation strategies to unstable environments. However, little is known about the underlying mechanisms of these phenomena, partly due to the lack of suitable model systems. We used phylogenetic and comparative analyses of fruit and seed anatomy, biomechanics, physiology, and environmental responses to study fruit and seed heteromorphism, a typical morphological basis of a bet-hedging strategy of plants, in the annual Brassicaceae species Aethionema arabicum. Our results indicate that heteromorphism evolved twice within the Aethionemeae, including once for the monophyletic annual Aethionema clade. The dimorphism of Ae. arabicum is associated with several anatomic, biomechanical, gene expression, and physiological differences between the fruit and seed morphs. However, fruit ratios and numbers change in response to different environmental conditions. Therefore, the life-history strategy of Ae. arabicum appears to be a blend of bet hedging and plasticity. Together with the available genomic resources, our results pave the way to use this species in future studies intended to unravel the molecular control of heteromorphism and plasticity.

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Section: Phenotypic Plasticity Of Fruit and Seed Heteromorphismsupporting

confidence: 90%

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confidence: 99%

Developmental Control and Plasticity of Fruit and Seed Dimorphism in Aethionema arabicum

et al. 2016

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“…The number of seeds of each morph and total number of seeds produced were not affected by whether the parent plant was raised from ray or disc seed. Interestingly, in Suaeda corniculata (Amaranthaceae), germination timing, rather than seed morph from which the parent plant originated, was a determinant of resulting seed morph ratios, so that the proportion of brown seeds produced on a plant increased if germination was delayed (Yang et al 2015). Whether germination timing influences any seed characteristics in B. ciliaris could not be determined, because all seeds were germinated at approximately the same time under laboratory conditions.…”

Section: Seed Dimorphism and Provenance Of Brachyscome Ciliaris Austrmentioning

confidence: 99%

Influence of seed dimorphism and provenance on seed morphology, dispersal, germination and seedling growth of Brachyscome ciliaris (Asteraceae)

et al. 2015

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Abstract. Brachyscome ciliaris is a floriferous Australian native daisy, with potential for use as a horticultural species. The species is hardy and seeds are relatively easy to germinate, but it is unique within the Brachyscome genus in that seeds are distinctly dimorphic. Within a fruiting capitulum, ray seeds are smooth and narrow with a minute pappus, whereas disc seeds have broad flat wings with curled hairs and a longer pappus than that of ray seeds. Both seed morphs, collected from five populations of the species, were tested to determine differences in their morphology, germination speed and percentage, seedling growth and wind-dispersal characteristics. Ray seeds were generally lighter and smaller than disc seeds and their length varied significantly with provenance. Dormancy levels of the two seed morphs and growth of rayand disc-derived seedlings did not differ significantly, but differences were significant among the five populations tested. Seeds germinated readily, and germination was optimal under winter or summer conditions and lower in spring or autumn. Seed production by plants raised from ray or disc seeds was identical, but Noora-sourced plants yielded more seed than did plants sourced from the other provenances tested. Seed size, germination and plant growth of B. ciliaris varied significantly among populations. Winged disc seeds were dispersed slightly further by wind than were wingless ray seeds. We concluded that dormancy, germination and seed-yield characteristics of B. ciliaris were all influenced more by seed provenance than by seed morph (ray or disc).

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“…, Yang et al. ). However, the riskier strategy for brown seeds, which emerge earlier when moisture availability is less certain during spring, is offset by their seedlings' ability to grow larger than those of black seeds, and produce correspondingly higher numbers of seeds by the end of the growing season.…”

Section: Introductionmentioning

confidence: 99%

“…, Gutterman , Yang et al. ). Despite the importance of the fire regime as a driver of population dynamics across the world, only a few studies have investigated seed heteromorphism in fire‐prone habitats (e.g., Hanley and Fenner , Hanley et al.…”

Section: Introductionmentioning

confidence: 99%

Seedling performance covaries with dormancy thresholds: maintaining cryptic seed heteromorphism in a fire‐prone system

Liyanage

Ayre

Ooi

2016

Ecology

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Abstract. The production of morphologically different seeds or fruits by the same individual plant is known as seed heteromorphism. Such variation is expected to be selected for in disturbance-prone environments to allow germination into inherently variable regeneration niches. However, there are few demonstrations that heteromorphic seed characteristics should be favored by selection or how they may be maintained. In fire-prone ecosystems, seed heteromorphism is found in the temperatures needed to break physical dormancy, with seeds responding to high or low temperatures, ensuring emergence under variable fire-regime-related soil heating. Because of the relationship between dormancy-breaking temperature thresholds and fire severity, we hypothesize that different post-fire resource conditions have selected for covarying seedling traits, which contribute to maintenance of such heteromorphism. Seeds with low thresholds emerge into competitive conditions, either after low-severity fire or in vegetation gaps, and are therefore likely to experience selection for seedling characteristics that make them good competitors. On the other hand, high-temperature-threshold seeds would emerge into less competitive environments, indicative of stand-clearing high-severity fires, and would not experience the same selective forces. We identified high and low-threshold seed morphs via dormancy-breaking heat treatments and germination trials for two study species and compared seed mass and other morphological characteristics between morphs. We then grew seedlings from the two different morphs, with and without competition, and measured growth and biomass allocation as indicators of seedling performance. Seedlings from lowthreshold seeds of both species performed better than their high-threshold counterparts, growing more quickly under competitive conditions, confirming that different performance can result from this seed characteristic. Seed mass or appearance did not differ between morphs, indicating that dormancy-breaking temperature threshold variation is a form of cryptic heteromorphism. The potential shown for the selective influence of different post-fire environmental conditions on seedling performance provides evidence of a mechanism for the maintenance of heteromorphic variation in dormancy-breaking temperature thresholds.

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Effects of germination time on seed morph ratio in a seed-dimorphic species and possible ecological significance

Cited by 32 publications

References 44 publications

Developmental Control and Plasticity of Fruit and Seed Dimorphism in Aethionema arabicum

Developmental Control and Plasticity of Fruit and Seed Dimorphism in Aethionema arabicum

Influence of seed dimorphism and provenance on seed morphology, dispersal, germination and seedling growth of Brachyscome ciliaris (Asteraceae)

Seedling performance covaries with dormancy thresholds: maintaining cryptic seed heteromorphism in a fire‐prone system

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