In 1842 the Irish potato crop was destroyed by the fungus Phytophthora Infestans, starving more than a million people to death.
Recent research by Jean Ristaino at
North Carolina State University has shown that this strain of P. Infestans is in fact not
related
to the modern, '1b' strain. By comparing the
DNA from 150 year old samples of
Irish potato famine struck potatoes from
Kew Gardens with that of the 1b strain, it was
found that the old strain lacked a
sequence found in all modern 1b strains; proving that 1b had a different ancestor.
The old strain is believed to have originated from
Mexico, which in fact has a great many strains of P. Infestans naturally occurring
there, but the modern strain comes from somewhere else. If the location of the modern strain's 'home' can be found, there will
probably be some potatoes there that have some natural
resistance to the
fungus, which could prove invaluable in protecting modern
day crops from this
infection.
Source :- New Scientist magazine, 9 June 2001, Nature (vol. 411, p 695)