Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2009
Publication Date: 1/15/2009
Citation: Klink, V.P., Hosseini, P., Macdonald, M.H., Alkharouf, N.W., Matthews, B.F. 2009. Population-specific gene expression in the pathogenic nematode Hederodera glycines exists prior to infection and during the onset of a resistant or susceptible reaction in the roots of Glycine max. Biomed Central (BMC) Genomics. 10:111. http://www.biomedcentral.com/1471-2164/10/111. 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 compared two different races of soybean cyst nematode to identify gene expression differences before they infected soybean roots and while they were infecting the roots. The soybean roots were susceptible to one nematode race and resistant to the other nematode race. Differential gene expression analysis identified 173 different genes that were induced and 111 genes suppressed in one nematode population as compared to the other. 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: Based on gene expression experiments, a single Glycine max (soybean) genotype (Peking) reacts differently to two different populations of Heterodera glycines (soybean cyst nematode) within the first twelve hours of infection. This suggested that H. glycines has population-specific gene expression signatures that could be present before nematodes had even infected Peking. A microarray analysis of ~7500 probesets on the Affymetrix® soybean Genechip® were used to identify population-specific gene expression signatures in preinfective second stage larva (pi-L2), the infective L2 at 12 hours post infection (i-L212hpi), and infective sedentary stages at three dpi (i-L23dpi) and eight days post infection (i-L38dpi). Differential expression analyses comparing populations of pi-L2 (i.e., incompatible population, NL1-RHp to compatible population, TN8) identified 173 genes that were induced in NL1-RHp as compared to TN8. The comparative analysis of pi-L2 identified 111 genes that were suppressed in NL1-RHp as compared to TN8. By 12 hours post infection, there were 145 induced genes and 3 suppressed genes. By three dpi, 19 induced and 13 suppressed genes were identified in NL1-RHp. Substantial changes in gene expression became evident subsequently. At eight dpi, 38 induced genes were found in NL1-RHp. However, 1668 genes were found to be suppressed. These analyses, thus, identify a genetic expression signature for these two populations as they undergo an incompatible or compatible reaction within the root of G. max.