Seminar "Reproductive Synchronization/de-synchronization in Plants in a Seasonal Environment: Flowering and Senescence timing in Arabidopsis thaliana" by Dr. Matin Miryeganeh, Kyoto University

Dear All,

Plant Epigenetics Unit (Saze unit) would like to invite you to a seminar by Dr. Matin Miryeganeh.

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Date: Tuesday, October 27^th  2015
Time:10:00-11:00
Venue: C015, Lab 1
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Speaker: Dr. Matin Miryeganeh, Center for Ecological Research, Kyoto University

Title: "Reproductive Synchronization/de-synchronization in Plants in a Seasonal Environment: Flowering and Senescence timing in Arabidopsis thaliana and Phylogeography of a pantropical plant with sea-drifted seeds, Ipomoea pes-caprae (Evidence from nuclear genes) "

Abstract:

Synchronous reproduction has long been noticed in plant populations since it is very important for successful mating and also seed maturation and dispersion. But there are no empirical studies focusing on the role of germination timing and the effect of age difference on reproductive synchronization. In order to distinguish between age-dependent and environment-dependent synchrony, plants of different age and experiencing the same environment, are needed. We conducted an experimental manipulation of germination timing by sequential seeding experiment using selected Arabidopsis thaliana accessions in outside environment to test whether the timing of post-germination life-history characteristics is influenced by germination timing and/or by seasonal condition. Strong senescence synchronization among cohorts was found regardless of their ages. As the growing season progressed, the older cohorts showed an increase in flowering period and delay in senescence, and younger cohorts did the opposite by decreasing in flowering period and an advance in senescence, suggesting that it was environmental conditions changes rather than age which were causing these senescence synchronization. To identify a genetic system that is regulating reproductive synchronization, time-series RNA sampling was done periodically during SSE experiment time. Gene expression comparison among different cohorts and different developmental stage of plant life span using q-RTPCR of selected flowering and senescence genes showed consistency between gene expression and phenological results. Synchronous flowering at the same time each year has long been noticed but this is the first study that proposes synchronous timing for floral senescence in plants with certain and known germination time.

   The second study intended to examine the importance of long distance seed dispersal in the integration of a Pantropical plant with sea-drifted seeds; Ipomoea pes-caprae (Convolvulaceae), which exhibits extraordinary wide distribution throughout tropical and subtropical regions. Unusual long-distance seed dispersal would be responsible for keeping the distribution of this single species; however, the level of inter-population migration has never been studied. I investigated the nucleotide sequence variations using 11 low copy nuclear markers and 272 samples collected from 34 populations covering the entire distribution range of the species at a global scale. Genetic structure and population differentiation in the wide distribution range of this species were evaluated, and migration rates, effective population sizes, and the population-divergence time were also estimated. I detected significant amount of gene flow among populations within the Indo West Pacific region (IWP) which is the sign of frequent long distance seed dispersal between populations of Indian and West Pacific Oceans. Furthermore, the gene flow analyses suggested that African continent land mass and East Pacific ocean might play a role as geographical barriers to gene flow between IWP and Atlantic East Pacific (AEP) regions. Overall, my study suggested that long distance dispersal by sea-drifted seeds is effective enough to keep the vast distribution range of a single species - Ipomoea pes-caprae – all over the globe.

We look forward to seeing many of you at the seminar.

Sincerely,
Yoko Fujitomi
Plant Epigenetics Unit (Saze unit)