1a.Objectives (from AD-416):
Build on previous work and study new opportunities to advance our abilities to manage late blight in commercial settings as well as breed resistant varieties.
Engineer durable R-genes using TALENs technology
Characterize late blight resistance of the best RB/conventionally bred progeny from previous work and continue to breed new late blight resistant combinations in elite breeding material
1b.Approach (from AD-416):
A multi-disciplinary approach will be undertaken to study P. infestans, apply emerging genetic approaches, breed resistant germplasm, conduct field studies, and provide recommendations to the growers. An understanding of molecular interactions between host R gene products and pathogen effectors has provided valuable data that will allow us to identify or engineer novel R-genes that can be used in breeding programs. Characterization of the overwintering ability of novel P. infestans genotypes as mycelia on currently grown potato varieties and as oospores in field soil will provide needed biological information to production scientists for estimating epidemic risk for improved control recommendations. Cooperator will be responsible for genetic marker analysis, followed by characterization of genetically modified plants containing the putative R-gene from S. microdontum located on Chr. 4.
This project was renumbered from 3655-21000-049-18S to 3655-21220-002-05S. In 2012, we field tested the S. microdontum-R-gene genetically modified (GM) lines against US-22. The results were promising with 6 of 10 lines showing little infection. These lines are being retested in 2013 as well as in agronomic trials.
In other research, we pyramided the RB-gene with natural resistance by crossing transgenic plants with other germplasm using conventional breeding techniques.
There were 14 lines that had very low levels of infection to US-22 in the field. We also combined resistance sources by creating S. berthaultii x S. microdontum hybrids. Six lines were resistant to US-22 in the field with resistance levels greater than the individual parental lines. The S. microdontum lines were used in 4x-2x crosses and 3 were advanced to late blight field trials that performed well. Through genetic engineering we created a series of RB lines that are in the background of the four different conventionally bred resistant lines. Detached leaf bioassays show that many of the lines have resistance to three different Phytophthora infestans isolates (US-8, US-22, and US-24). These lines are currently in late blight field trials to assess field resistance to US-22. This research relates to objective 1 of the project through testing of genetically modified potatoes with the resistance gene from Solanum microdontum.