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The $\gamma-$ray emission from flat-spectrum radio quasars (FSRQs) is thoughtto be dominated by the inverse Compton scattering of the external sources ofphoton fields, e.g., accretion disk, broad-line region (BLR), and torus. FSRQsshow strong optical emission lines and hence can be a useful probe of thevariability in BLR output, which is the reprocessed disk emission. We study theconnection between the optical continuum, H$\gamma$ line, and $\gamma-$rayemissions from the FSRQ PKS~1222+216, using long-term ($\sim$2011-2018) opticalspectroscopic data from Steward Observatory and $\gamma-$ray observations from$Fermi$-LAT. We measured the continuum ($F_{C,opt}$) and H$\gamma$($F_{H\gamma}$) fluxes by performing a systematic analysis of the 6029-6452\r{A} optical spectra. We observed stronger variability in $F_{C,opt}$ than$F_{H\gamma}$, an inverse correlation between H$\gamma$ equivalent width and$F_{C,opt}$, and a redder-when-brighter trend. Using discrete cross-correlationanalysis, we found a positive correlation (DCF$\sim$0.5) between$F_{\gamma-ray>100MeV}$ and $F_{C,opt}$ (6024-6092 \r{A}) light curves withtime-lag consistent with zero at 2$\sigma$ level. We found no correlationbetween $F_{\gamma-ray>100MeV}$ and $F_{H\gamma}$ light curves, probablydismissing the disk contribution to the optical and $\gamma$-ray variability.The observed strong variability in the $Fermi$-LAT flux and$F_{\gamma-ray>100MeV}-F_{C,opt}$ correlation could be due to the changes inthe particle acceleration at various epochs. We derived theoptical-to-$\gamma$-ray spectral energy distributions (SEDs) during the$\gamma$-ray flaring and quiescent epochs that show a dominant disk componentwith no variability. Our study suggests that the $\gamma$-ray emission zone islikely located at the edge of the BLR or in the radiation field of the torus.

Long-term optical and $\gamma-$ray variability of the blazar PKS~1222+216