**7. Conclusion and future perspectives**

Although our understanding of NO interactions with plant hormones has increased dramatically in past few years, many pieces of the puzzle are still missing. It is well established that NO coordinates with plant hormones to regulate gene expression and activities of anti-oxidative enzymes under adverse environmental conditions. However, our current knowledge about NO-phytohormone interactions is derived chiefly from NO-induced posttranslational modifications of transcription factors and biosynthetic enzymes. Future work is needed to explore the interplay among NO, plant hormones, ROS, protein kinases, and cytoskeletal proteins in order to understand the complicated network of NO signaling under abiotic stress conditions. Interestingly, most of the studies related to NO-phytohormonal interactions involve experiments in controlled laboratory environments, very little is known about the cross talk between these signaling molecules during flower initiation or grain development. Moreover, plants growing under natural conditions face multiple stresses; hence, future studies will need to address how NO interacts with the signaling cascades of phytohormones in plants exposed to two or more abiotic stresses.
