sentences:  Carotenoids are absolutely necessary not only for the production of trisporic acid, but also for the process of zygote formation, as significant factors for the production of sporopollenin, a structural component of the zygospore cell wall.It is consequential to regulate this feedback-type synthesis with carotenoids and further synthesis of TSA.Therefore, the formation of the zygospores can be prevented by the inhibition of carotenogenesis in "Blakeslea trispora".