Poster: Seed Biology

Abs # 545: A search for genes responsible for dormancy breaking in the seeds of Arabidopsis thaliana ecotype

Presenter:	Fujikura, Ushio , 55020036@nodai.ac.jp
Authors	Fujikura, Ushio  (A)   Yasuyuki, Kawaharada  (A)   Koji, Koizumi  (A)   Yoichi, Sakata  (A)   Shigeo, Tanaka  (A)
Affiliations:	(A): Department of Bioscience, Tokyo University of Agriculture

Seeds exist in a dormant state to survive in extreme environments. Little is known about seed dormancy in arabidopsis because the seeds of the most frequently-used ecotypes, Landsberg erecta (Ler) and Columbia (Col), enter a temporal period of dormancy after ripening and awake from dormancy only in a month without any artificial treatments with dormancy breakers such as coldness, chemicals and plant hormones. To investigate the regulatory mechanism by which cold treatment of seeds breaks dormancy, we examined the dormancy of 31 ecotypes of arabidopsis, generous gifts from ABRC. As a result, we found that an ecotype Abd-0 remained dormant at a temperature of 23��C, but its dormancy was broken by cold treatment (4��C) for 6 days. No dormancy breaking took place in the seeds grown in the presence of paclobutrazol (GA biosynthesis inhibitor), even though they were imbibed at 4��C. Interestingly the subsequent treatment of seeds with GA ₃₊₄ showed that only the seeds exposed to cold awoke from dormancy. These results suggest that cold treatment may break the dormancy of Abd-0 at a stage of germination prior to GA biosynthesis. Genetic studies showed that F1 seeds from reciprocal crosses between Abd-0 and Col / Ler were all dormant, and the Abd-0 phenotype was suggested to be transmitted through a nuclear dominant gene. Further molecular studies are in progress to elucidate genes responsible for dormancy breaking in the seeds of arabidopsis by using map-based cloning.