Development of late blight resistant potatoes by cisgene stacking

Area of Science:

• Plant breeding and genetics
• Molecular biology
• Agricultural science

Background:

• Late blight, caused by Phytophthora infestans, is a major threat to potato production.
• Developing late blight resistance in potato is a critical breeding objective.
• Cisgenesis offers a method to introduce native resistance genes using genetic modification.

Purpose of the Study:

• To introduce two broad-spectrum late blight resistance (R) genes, Rpi-sto1 and Rpi-vnt1.1, into three potato varieties using cisgenesis.
• To develop and evaluate a marker-free transformation pipeline for stacking R genes.
• To compare marker-free transformation with marker-assisted transformation.

Main Methods:

• Agrobacterium-mediated transformation was used to introduce Rpi-sto1 and Rpi-vnt1.1 into potato varieties.
• PCR was used to confirm gene transfer.
• Greenhouse evaluations, Avr gene responsiveness assays, and detached leaf assays were performed to assess resistance.
• Marker-free transformation was compared to kanamycin resistance-assisted transformation.

Main Results:

• Eight independent cisgenic events exhibiting broad-spectrum late blight resistance were selected.
• The introduced R genes (Rpi-sto1 and Rpi-vnt1.1) conferred resistance in the potato varieties.
• Marker-free transformation showed reduced genotype dependency and vector backbone integration compared to marker-assisted transformation.

Conclusions:

• A marker-free transformation pipeline was successfully developed for stacking late blight R genes in potato.
• This approach facilitates the deployment of multiple R genes for durable resistance.
• The study provides a valuable tool for developing blight-resistant potato varieties.