Deletion of BSG1 in $Chlamydomonas\ reinhardtii$ leads to abnormal starch granule size and morphology
Résumé
Chlamydomonas reinhardtii represents an ideal model microbial system to decipher starch metabolism.
In this green algae, in cells growing in photosynthetic conditions, starch mainly accumulates as a
sheath surrounding the pyrenoid while in cells subjected to a nutrient starvation, numerous starch
granules are flling up the plastid stroma. The mechanisms underlying and regulating this switch
from photosynthetic to storage starch metabolisms are not known. In this work, we have isolated a
Chlamydomonas mutant strain containing a deletion in chromosome 2 which displays abnormal starch
granule distribution. Under nitrogen starvation, this strain contains an additional starch granules
population. These granules are twice as big as the wild-type granules and display characteristics of
photosynthetic starch. Genetic and functional complementation analyses allowed us to identify the
gene responsible for this original phenotype which was called BSG1 for “Bimodal Starch Granule”.
Possible roles of BSG1 in starch metabolism modifcations during the transition from photosynthetic to
starved growth conditions are discussed.
Domaines
Sciences du Vivant [q-bio]| Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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