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Poster: Molecular & Cellular Plant-Microbe Interactions: Plant Defense Responses


miR858 functions as a negative regulator of plant susceptibility to the beet cyst nematode Heterodera schachtii
S. PIYA (1), T. Baum (2), T. Hewezi (1) (1) University of Tennessee, U.S.A.; (2) Iowa State University, U.S.A.

Recent studies have indicated that microRNA genes play key roles in shaping the compatibility of the interaction between plant-parasitic cyst nematodes and host plants. In this study, we report a novel regulatory role of the Arabidopsis miR858 and its MYB83 transcription factor during plant-cyst nematode interactions. Promoter–GUS fusion assays pointed to a role of miR858 in post-transcriptional regulation of MYB83 in the syncytium induced by the beet cyst nematode Heterodera schachtii. qPCR quantification further supported the negative association between miR858 and MYB83 expression levels at different time points post H. schachtii infection. Overexpression of miR858 in Arabidopsis resulted in significant decreases of plant susceptibility to infection by H. schachtii, whereas a mir858 mutant showed the opposite effect of increased susceptibility. In addition, we found that T-DNA insertional mutation of MYB83 was less susceptible to nematode infection. In contrast, overexpression of miR858–resistant myb83 produced hyper-susceptibility phenotypes. Taken together, these data revealed the importance of tight regulation of MYB83 transcription factor expression by miR858 in the syncytium, apparently to control downstream target genes that encode components that may be needed for syncytium formation/function. Identification of target genes that are directly or indirectly regulated by MYB83 is currently underway.