A gene expression analysis of syncytia isolated from the roots of the Glycine max (soybean) genotype PI 548402 (Peking) undergoing a resistant reaction after infection by Heterodera glycines (soybean cyst nematode)

Authors: KLINK, V - Mississippi State University; HOUSSEINI, P - Towson University; MATSYE, P - Mississippi State University; ALKHAROUF, N - Towson University; Matthews, Benjamin - Ben

Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2009
Publication Date: 9/29/2009
Citation: Klink, V., Housseini, P., Matsye, P., Alkharouf, N., Matthews, B.F. 2009. A gene expression analysis of syncytia isolated from the roots of the Glycine max (soybean) genotype PI 548402 (Peking) undergoing a resistant reaction after infection by Heterodera glycines (soybean cyst nematode). Plant Molecular Biology. 71:525-567.

Interpretive Summary: The soybean cyst nematode is the major pest of soybean and causes an estimated one billion dollars in damages annually in the U.S. There are numerous races of soybean cyst nematode and current soybean cultivars grown in the U.S. are not resistant to all races. We collected soybean cells specifically at the nematode feeding site in the root of the soybean cultivar Peking that exhibited a resistant reaction with one nematode race and a susceptible reaction with a different nematode race. Then we identified genes expressed by soybean roots in each of these samples from the feeding sites. Analysis of gene expression identified differentially expressed genes belonging to specific pathways related to plant defense, including a pathway leading to cell wall synthesis. Some of these genes may be targets for modification to control soybean cyst nematode development. These data are of interest to scientists seeking new methods to broaden resistance of soybean to soybean cyst nematodes.

Technical Abstract: The syncytium, a feeding cell formed by the plant parasitic nematode Heterodera glycines, is either maintained by the interaction between the nematode and the plant cell during the course of its life cycle or experiences degradation as a consequence of a disturbance between that interaction. The localized gene expression at the syncytium occurring during the resistance response was studied. This was accomplished by isolating syncytial cells from Glycine max genotype Peking (PI 548402) by laser capture microdissection (LCM). Comparative microarray analyses using the Affymetrix® soybean GeneChip® directly compared Peking syncytia undergoing a resistant reaction to those undergoing a susceptible reaction. Those analyses revealed lipoxygenase-9 and lipoxygenase-4 as the most highly induced genes in the resistant reaction. The analysis also identified induced levels of components of the phenylpropanoid pathway. These genes included phenylalanne ammonia lyase (PAL), chalcone isomerase, isoflavone reductase, cinnamoyl-CoA reductase (CCR) and caffeic acid O-methyltransferase (COMT). The identification of these genes imply the importance of jasmonic acid and phenylpropanoid signaling pathways locally at the site of the syncytium during the resistance response. The analysis also identified highly induced levels of four S-adenosylmethionine synthetase (SAM) genes, the EARLY-RESPONSIVE TO DEHYDRATION 2 (ERD2/HSP70T-1) gene and the 14-3-3 gene known as GENERAL REGULATORY FACTOR 2 (GRF2). Subsequent analyses studied microdissected syncytial cells at 3, 6 and 9 days post infection (dpi) during the course of the resistant response, resulting in the identification of signature gene expression profiles at each time point in a single G. max genotype (Peking).