The validity of SU(4)-flavor symmetry relations of couplings of charmed $D$ mesons to light mesons and baryons is examined with the use of $^3{rm P}_0$ quark-pair creation model and nonrelativistic quark model wave functions. We focus on the three-meson couplings $pipirho$, $KKrho$ and $DDrho$ and baryon-baryon-meson couplings $NNpi$, $NLambda K$ and $NLambda_c D$. It is found that SU(4)-flavor symmetry is broken at the level of 30% in the $DDrho$ tree-meson couplings and 20% in the baryon-baryon-meson couplings. Consequences of these findings for DN cross sections and existence of bound states D-mesons in nuclei are discussed.
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