Article

Effect of light on endogenous levels of gibberellin and abscisic acid in seed germination of photoblastic weedy rice (Oryza sativa L.)

Journal of Crop Science and Biotechnology 09/2009; 12(3):149-152. DOI: 10.1007/s12892-009-0110-z

ABSTRACT The effect of red (R) and R/far-red (FR) lights on endogenous gibberellin (GA) and abscisic acid (ABA) content was first investigated
during the germination of photoblastic black-hulled weedy rice (PBWR) seeds. The R light-treated PBWR seeds germinated after
36–48 h and germination was increased to 63% at 72 h. However, the FR light-treated seeds after R light treatment, suppressed
the R light effect showing only 11% germination even at 72 h after the light treatment. The PBWR seed treated with R light
rapidly increased the endogenous level of GA1 to about 200 times at 12 h before seed germination as compared with R/FR (control) which suppressed the effect of R light.
The contents of other GAs like GA12, GA53, GA19, GA20, and GA8 were not affected by the R light irradiation. These results showed that the major biosynthetic pathway of GAs in PBWR seeds
is the early 13-hydroxylation pathway leading to GA1, which was suggested to be physiologically active in the PBWR seed germination. The decrease in the level of ABA in the R
light-treated seeds was greater than the R/FR light-treated seeds, indicating that the balance of endogenous GA1 and ABA is
responsible for the induction of germination in the PBWR seed.

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