Submitted to: Journal of Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2018
Publication Date: 2/26/2019
Citation: Lawrence, S.D., Novak, N.G., Perez, F.G., Jones, R.W. 2019. Over expression of the Q-type ZFP StZFP2 in potato increases resistance to potato late blight (Phytophthora infestans) infection. Journal of Plant Interactions. 14(1):129-136. https://doi.org/10.1080/17429145.2018.1562109.
Interpretive Summary: Microbial infection of plants cause diseases that reduce food crop production. Various treatments such as chemical fungicides are used on a regular basis to thwart the microbial attack on plants. There are natural defenses present in plants that can limit infection and spread of microbes, and these plant defenses can be an effective mechanism of disease prevention. Studies were undertaken to modify genes for plant defenses by keeping them active all the time. Testing this idea in potato plants, it was found that microbial invasion and early spread of the most destructive microbial pathogen of potato that causes late blight disease was significantly reduced when the plant defenses were kept continually active. This information can be used by plant scientists trying to develop disease resistant plants through breeding or transgenic plant production.
Technical Abstract: Late blight in potato caused by Phytophthora infestans remains a major impediment to potato growers worldwide. The need for additional control practices elicits alternative approaches to deterring this important agricultural disease. Utilization of or understanding transcription factors that affect defense may ultimately augment control measures to achieve a basal defense against late blight. This work examines the effect of over-expressing the transcription factor StZFP2 in potato on Phytophthora infestans infection. StZFP2 is a C2H2 zinc finger transcription factor that is induced upon wounding or infestation by chewing insects such as Manduca sexta (Tobacco horn worm (THW) and Colorado potato beetle (CPB). It is also induced by exposure to Phytophthora infestans. The coding region of StZFP2 was transformed into potato (Solanum tuberosum var. Kennebec) under the control of the CaMV 35S promoter. Three over-expressing lines (OE-StZFP2) resulted in significantly lower lesion size five days after infection (DAI). However, by 8DAI the lesion size in these lines was not significantly smaller. Therefore the increased expression of StZFP2 slows the spread of infection at 5DAI. Transcript levels of StZFP2 and classic pathogen response (PR) marker genes StNPR1, StPR-1b, and StPAL were examined at 3DAI. The amount of StPR-1b was significantly lower in the more resistant lines compared to Kennebec. This suggests that the constitutive increase in levels of StZFP2 affects this pathogen response. StPR-1b is induced by salicylic acid and is part of the response to biotrophs. Considering that their levels are repressed in these OE-StZFP2 lines is initially counterintuitive to increased resistance to P. infestans spread within the leaf. Although the OE-StZFP2 lines are more resistant to lesion formation by P. infestans at or prior to 5DAI, the SA pathway marker StPR-1b is repressed, suggesting that increased levels of StZFP2 may negatively regulate this pathway.