Why there is a sudden change in the colour of the tulip flowers from white to variously coloured like red,etc?

it is regarding mutation

Why there is a sudden change in the colour of the tulip flowers from white to variously coloured like red,etc?
Are you talking about color breaks, like you see in the "Rembrandt" tulips? The commercial ones now are genetically "color broken", while the ones that set off the Dutch "tulip mania" of the 1600s were infected with a virus called Tulip Breaking Virus, the first viral plant disease identified.





Viral breaking:


http://nu-distance.unl.edu/homer/disease...


http://www.apsnet.org/pd/pdfs/2000/0822-...





If you're talking about the genetics of color variation in tulip flowers, like the blue bottom of the tepals in some purple cultivars:


http://ss.jircas.affrc.go.jp/english/pub...





Periclinal and sectorial chimeras are known.