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Title: Detection of gene expression changes in Capsicum annuum L. leaf foliar blight caused by Phytophthora capsici Leon. using qRT-PCR and leaf discs

item JONES, RHIANA - New Mexico State University
item BOSLAND, PAUL - New Mexico State University
item STEINER, ROBERT - New Mexico State University
item Jones, Richard
item O'CONNELL, MARY - New Mexico State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2015
Publication Date: 9/21/2015
Publication URL:
Citation: Jones, R.F., Bosland, P.W., Steiner, R.L., Jones, R.W., O'Connell, M.A. 2015. Detection of gene expression changes in Capsicum annuum L. leaf foliar blight caused by Phytophthora capsici Leon. using qRT-PCR and leaf discs. HortScience. 50(9):1342-1348.

Interpretive Summary: Plants are susceptible to various diseases that limit productivity. While various cultivation techniques can be used to limit disease losses, plant disease resistance is the preferred method for disease control. While resistant plants are known, the genetic basis for their resistance is often unknown. We have investigated four specific genes in pepper that may contribute to disease resistance. Increased activity of two of these genes in response to fungal infection suggests a role for these genes in resistance to attack by pathogens. This information will be useful for scientists studying gene function in disease resistance, and for breeders when selecting resistant plants.

Technical Abstract: Phytophthora capsici is responsible for multiple disease syndromes of Capsicum annuum but the resistance mechanism is still unknown. Evaluating gene expression during foliar blight can be used to identify expression patterns associated with resistance in Capsicum species. This study reports a direct comparison of gene expression changes during the foliar blight syndrome using two different races of P. capsici on C. annuum host plants with resistant and susceptible phenotypes to those races. Pathogenesis Related (PR) genes were evaluated for differential expression following leaf inoculation with P. capsici. RNA isolated from leaves at three time points was used to quantify gene expression by qRT-PCR. Of four genes tested, two had differential expression in response to P. capsici at 72 h post-inoculation, a xyloglucan specific endo-'-1,4-glucanase inhibitor protein (XEGIP2) in susceptible cultivar New Mexico Heritage 6-4 (NMH 6-4), and a C. annuum cell wall protein (CWP) in resistant Criollo de Morelos 334 (CM334). Both genes had a five-fold increase in transcription in leaves over the control. These results suggest that both genes are playing a role in disease resistance to foliar blight.