Poodles that do not have this, will have the Pheomelanin enzyme instead, which would create a light colored coat.
So, to begin a Poodle may have the eumelanin enzyme and then in order to be a true black, there has to be two accessory enzymes that must be there as well, known as TRP1 and TRP2.
Since dogs carry genes from both parents, a Poodle with 2 black color genes has the genotype of BB.
If a Poodle has one black and one brown gene factor, the genotype is Bb; however black is dominant over brown and the coat would be black. That Poodle, however - if bred- will pass down the Bb gene, which could produce black or brown puppies, depending one which gene the other parent passes down.