The genetic code of late blight - the plant pathogen that lead to the Irish potato famine of the 1840s and 1850s- has been unlocked and clues regarding it being such a enemy of the potato have been revealed by Scientists.

They found that late blight or Phytophthora infestans genome is almost animal-sized and have an extra DNA that permits it to adapt quickly to surpass the defense of the host plant.

"The genome is much larger than some of its relatives. The reason is it is full of these jumping genes that copy themselves," said Chad Nusbaum of the Broad Institute of Massachusetts Institute of Technology and Harvard.

He added that 75 percent of this genome is filled with repetitive DNA, which appears to evolve quickly and this explains why this disease has been able to attack even potatoes that are bred genetically to resist infection.

This disease continues to be a threat to the global food security. It is currently damaging potato and tomato plants in home gardens in the United States.

It can wipe out a crop in days and causes large mold-ringed olive-green or brown spots on leaves and blackens the stems.

Scientists found that the late blight genome is 2.5 to four times larger in size with two different regions. One of these contains DNA that undergoes quick change and has genes that have been preserved over millions of years of evolution. The other area has a handful of genes which play a part in plant infection.

It may still take many more years for the scientists to find out what these genes do but they now have more tools to do so.