AOBPreview originally published online on April 28, 2009
Annals of Botany 2009 104(1):115-124; doi:10.1093/aob/mcp100
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Ageing effects in an iteroparous plant species with a variable life span
Laboratoire Génétique et Evolution des Populations Végétales, UMR 8016, CNRS, Université Lille 1, F-59655 Villeneuve d'Ascq, France
* For correspondence. E-mail henk.van-dijk{at}univ-lille1.fr
Received: 10 December 2008 Returned for revision: 10 February 2009 Accepted: 24 March 2009 Published electronically: 28 April 2009
Background and Aims: Ageing effects may be due to dysfunction leading to decreasing reproduction and survival with age. In plants, however, other (physiological) causes, associated with size for example, may also play a role. Iteroparous plants with genetically variable life spans can be helpful in unravelling these two aspects of changes associated with growing older.
Methods: In a long-term experiment, Beta vulgaris ssp. maritima (sea beet) plants from the same set of populations but with different ages were compared for flowering date over several years. Flowering date, root growth and seed production were measured in a synthetic population and in progenies derived from reciprocal crosses over three consecutive years and analysed with respect to the number of years yet to live. Heritabilities of these three characters and of life span were estimated.
Key Results: Flowering occurred on average 1·3 d later each year over a plant's whole lifetime. In the year before dying, plants flowered on average 3·3 d later and both root investment and seed production decreased significantly compared with plants that remained alive for at least 1 further year. The negative relationship (trade-off) between reproduction and root investment in early life became positive near the end of life, and the positive relationship between flowering date and root growth became negative.
Conclusions: Effects of ageing – in the sense of a decline in reproduction and root storage – combined with later flowering were particularly pronounced in the year before death. The gradual change in flowering phenology, observed over the whole lifetime, could have a physiological basis unrelated to dysfunction.
Key words: Ageing, Beta vulgaris ssp. maritima (sea beet), flowering phenology, longevity, perennial, root investment, seed production, trade-offs, whole-plant senescence
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