Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2011
Publication Date: 3/23/2011
Citation: Tucker, M.L., Murphy, C.A., Yang, R. 2011. Analysis of gene expression profiles for cell wall modifying proteins and ACC synthases in soybean cyst nematode colonized roots, adventitious rooting hypocotyls, root tips, flooded roots, and IBA and ACC treatment roots. Plant Physiology. 156:319-329. Interpretive Summary: Soybean cyst nematode (SCN) is the most economically damaging pathogen of soybean costing U.S. farmers an estimated one billion dollars annually. SCN penetrates the soybean root and forms a feeding structure that involves changes in the concentration of plant hormones and root cellular structure. We examined changes in gene activity associated with SCN root infection and compared the change in gene activity to other developmental processes in soybean. The results indicate that nematode infection initiates changes in gene activity that are similar to what is seen when roots are chemically induced to grow out of the plant stem. A better understanding of how the nematode alters plant hormone concentration and other developmental signals will greatly improve the ability of scientists and industrial partners to control SCN infection of soybean.
Technical Abstract: We hypothesized that soybean cyst nematode (SCN) co-opts a part or all of one or more innate developmental process in soybean to establish its feeding structure, syncytium, in soybean roots. The syncytium in soybean roots is formed in a predominantly lateral direction within the vascular bundle by partial degradation of cell walls and membranes between adjacent parenchyma cells. A mature syncytium can incorporate as many as 200 cells into one large multinucleated cell. Gene expression patterns for cell wall modifying proteins and ACC synthases were compared in SCN colonized and non-colonized root pieces, root tips where vascular differentiation occurs, flooded roots (aerenchyma), 2.8% oxygen (aerenchyma), adventitious rooting in hypocotyls, and leaf abscission zones. In addition to these developmental programs, because both auxin and ethylene are implicated in SCN colonization of roots, we compared gene expression patterns associated with treatment of roots with IBA and 1-aminocyclopropane-1-carboxylic acid (ACC). Interestingly, the most similar pattern of gene expression to SCN colonize roots was rooting hypocotyls, but there were also similarities to abscission. These observations suggest that SCN-induced syncytium formation and cell separation in adventitious rooting and possibly abscission might share common inductive signals originating from either the nematode or the plant.