New insights into potato-pathogen battle through DNA sequencing

USA – Researchers at North Carolina State University have made significant strides in understanding the ongoing battle between potato plants and the destructive pathogen, Phytophthora infestans.

By leveraging advanced DNA sequencing technology, the team has unveiled crucial details about how this pathogen manages to overcome plant resistance strategies.

This groundbreaking study offers a fresh perspective on the evolutionary dynamics between potato plants and their adversary.

For the first time, researchers have used a targeted enrichment sequencing method to examine both the pathogen’s effector genes, which aid in infection, and the plant’s resistance genes simultaneously.

Allison Coomber, a graduate student researcher at NC State and lead author of the study, explained, “We use small pieces of historic potato leaves infected with the pathogen and other bacteria. The DNA is fragmented more than usual, so we use small 80 base-pair chunks like a magnet to isolate similar pieces from this mix. These magnets help us locate resistance genes in the host and effector genes in the pathogen.”

Jean Ristaino, the William Neal Reynolds Professor of Plant Pathology at NC State and corresponding author of the paper, highlighted the significance of this dual-enrichment approach.

“Typically, researchers focus on either the pathogen or the host. Our method allowed us to capture targeted regions of both genomes simultaneously, even when their amounts were unequal. This wasn’t possible 15 years ago due to limitations in genome sequencing technology,” Ristaino noted.

The research reveals that Phytophthora infestans is exceptionally adept at countering resistance in potatoes. The study demonstrates that the pathogen’s FAM-1 strain could overcome the R1 resistance gene before it was even introduced into potato varieties.

Coomber remarked, “The pathogen was likely exposed to a potato with this resistance gene in the wild, which enabled it to counteract it even before breeders deployed it.”

Despite various mutations, many of the pathogen’s effector genes have remained stable. This stability suggests that these genes are crucial to the pathogen’s survival and adaptation.

The study also shows that over the period from 1845 to 1954, the pathogen acquired a pair of chromosomes, adding another layer of complexity to its evolution.

Ristaino emphasizes that understanding these genetic interactions can greatly benefit plant breeders.

“With insights into which effectors have changed over time, breeders might focus on more stable resistance genes or combine multiple resistance genes from different wild sources. This knowledge can help slow down the pathogen’s ability to evolve resistance,” he said.

This research opens new possibilities for more effective potato breeding strategies, offering hope for better management of Phytophthora infestans and improved crop resilience in the future.