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Title: The genetics of leaf flecking in maize and its relationship to plant defense and disease resistance

Author
item OLUKOLU, BODE - North Carolina State University
item BIAN, YANG - North Carolina State University
item DE VRIES, BRIAN - University Of Wisconsin
item TRACY, WILLIAM - University Of Wisconsin
item WISSER, RANDALL - University Of Delaware
item Holland, Jim - Jim
item Balint-Kurti, Peter

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2016
Publication Date: 11/1/2016
Citation: Olukolu, B., Bian, Y., De Vries, B., Tracy, W.F., Wisser, R., Holland, J.B., Balint Kurti, P.J. 2016. The genetics of leaf flecking in maize and its relationship to plant defense and disease resistance. Plant Physiology. 172(3):1787-1803.

Interpretive Summary: In this paper we look at the phenomenon of leaf flecking , a common feature of maize lines in which small spots or flecks appear on the leaves. We described its genetic basis and show that this trait is related to disease reisstance and the defense reponse. We suggest that this trait can be used as a visual marker by maize breeders for lines with enhanced disease resistance.

Technical Abstract: Physiological/genetic leaf spotting, or flecking, is a mild lesion phenotype observed on the leaves of several commonly used maize inbred lines and has been anecdotally linked to enhanced broad-spectrum disease resistance. Flecking was assessed in the maize nested association mapping (NAM) population, comprising 4998 recombinant inbred lines from 25 bi-parental families, and in an association population comprised of 279 diverse maize inbreds. Joint linkage analysis was conducted with 7386 markers in the NAM population, and genome-wide association tests were performed with 26.5 million SNPs in NAM and with 246,497 SNPs in the association panel, resulting in the identification of 18 and one associated loci, respectively. Many of the candidate genes co-localizing with associated SNPs are similar to genes that function in plant defense response via cell wall modification, salicylic acid and jasmonic acid-dependent pathways, redox homeostasis, stress response and vesicle trafficking/remodeling. Significant positive correlations were found between increased flecking, stronger defense response and increased disease resistance, increased pest resistance and reduced yield. Mild flecking appeared to be associated with increased disease resistance but not with yield loss, suggesting that this phenotype could be used as a selection criterion for breeding programs trying to incorporate broad-spectrum disease resistance.