Influence of seed banking on seed and plant traits in rare and threatened plants

Diplôme Master Influence of seed banking on seed and plant traits in rare and threatened plants eng 2022-09-14 2022-09-14 author Logeswaran Shineka 0000-0002-2624-1385 821301 director Ensslin Andreas director Price Michelle 556219 With the current accelerating global warming, the conservation of seeds in the seed bank has become an important tool in the conservation of threatened plants and it is increasing worldwide. The objective of a seed bank is to conserve seeds of endangered species to backup populations threatened with extinction as well as to be able to reintroduce them into the wild. For that, it is also important that a seed collection represents the genetic diversity of the wild population. In the seed bank, the seeds are kept dried at 15% HR and frozen at -20°C ; conditions, which have been identified to optimise the seed longevity, i.e. the time a seed remains viable without germinating (Guerrant, 2004). Although the majority of seeds from European species generally withstand this treatment, seed aging and death during storage time is still an issue and very few studies have been carried out on the consequences of seed banking on the seeds and the traits of the plants grown out of the surviving seeds. This is however crucial to understand the long term impact of seed banking on the genetic diversity and trait composition of banked seed collection and their value for conservation and reintroduction. In my work, I seek to understand the effect of seed banking on seeds. For that, I compared seeds of ten annual species preserved in the seed bank (hereafter seed bank seeds) with the seeds of same species re-collected in the same location in the wild (hereafter wild seeds). To investigate long term storage of seeds, I also realised two accelerated aging tests (AA), which simulate the effects of long term seed storage (several decades) in a very short time (several weeks). I performed germination tests to see the effects of seed storage on germination and to compare the seed mortality between the two origins. In total, 15’565 seeds were used from ten species for the tests. Seedlings from three species who survived were transferred to pots. Once plants grew, I measured some morphological traits in three species and phenological traits in one species. Biomass was also measured from the dried aboveground part of the plants in two species. The results shows that no significant difference was observed in germination and survival between the seed from the seed bank and seed from the wild. In both origins, germination rate decreased during treatment, but mortality rate was low, which suggests that the seeds are dormant. In plant state, some morphological and phenological traits differences between plants from seed bank and wild seeds were visible. The height and the number of seeds produced per fruit of Spergularia plant after the AA test dropped in seed bank plants but not in wild plants, suggesting increased sensitivity to the aging treatment in banked seeds. Seed storage time affected germination ability but not the viability of the seeds, supporting the observation from the AA tests that reduced germination was more due to increased dormancy than to mortality. Altogether, my study shows that seeds has still the ability to germinate and so making this ungerminated seed fraction germinate would effectively reduce the invisible fraction and prevent a shift in plant characters from banked seeds. Dewey 580 45 Département des sciences végétales 163 false 1240 Laboratory of Plant Systematics and Biodiversity 56ab9cb7-aef3-4802-8856-930364f57090 Master thesis Restricted TravailDeMaster_2022-final.pdf 1972989 application/pdf restrictedAccess Faculté des sciences / Section de biologie / Département des sciences végétales

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Influence of seed banking on seed and plant traits in rare and threatened plants				2022	73	3

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Logeswaran, Shineka

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