The plant is an annual herb, 1 2 m tall.
But an international team of scientists, using DNA from Irish potato leaves preserved since 1847, said they had found the real culprit: a previously unknown strain of Phytophthora infestans (a funguslike microbe) they called HERB-1.
They found that the strain that caused the famine, which they named HERB-1, emerged in the early 19th century, probably in the United States or Mexico.
The US-1 strain, which has been blamed for the fatal blight, is closely related to HERB-1 and arose from the same population.
Rather, HERB-1 and US-1 are sister groups that share a common ancestor.
On the other hand, we could rebuild full length of AVR2 from HERB-1 reads.
Suggested paths of migration and diversification of P. infestans lineages HERB-1 and US-1.
Conversely, the first R genes for P. infestans resistance, introduced into cultivated potato only after the dates for our HERB-1 samples, should be effective against HERB-1 strains, which are predicted to carry matching avirulence effector genes.
The focus is on AVR3a, and it is interesting that the KI allele alone exists in the HERB-1 lineage.
Historic strains from different geographic locations all carried a mtDNA haplotype, HERB-1, that had not been recognized before.
