Klink Vincent P, Hosseini Parsa, MacDonald Margaret H, Alkharouf Nadim W, Matthews Benjamin F
Department of Biological Sciences, Harned Hall, Mississippi State University, Mississippi State, MS 39762, USA.
BMC Genomics. 2009 Mar 16;10:111. doi: 10.1186/1471-2164-10-111.
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 during resistant (R) and susceptible (S) reactions. This suggested that H. glycines has population-specific gene expression signatures. A microarray analysis of 7539 probe sets representing 7431 transcripts on the Affymetrix soybean GeneChip were used to identify population-specific gene expression signatures in pre-infective second stage larva (pi-L2) prior to their infection of Peking. Other analyses focused on the infective L2 at 12 hours post infection (i-L2(12h)), and the infective sedentary stages at 3 days post infection (i-L2(3d)) and 8 days post infection (i-L2/L3(8d)).
Differential expression and false discovery rate (FDR) analyses comparing populations of pi-L2 (i.e., incompatible population, NL1-RHg to compatible population, TN8) identified 71 genes that were induced in NL1-RHg as compared to TN8. These genes included putative gland protein G23G12, putative esophageal gland protein Hgg-20 and arginine kinase. The comparative analysis of pi-L2 identified 44 genes that were suppressed in NL1-RHg as compared to TN8. These genes included a different Hgg-20 gene, an EXPB1 protein and a cuticular collagen. By 12 h, there were 7 induced genes and 0 suppressed genes in NL1-RHg. By 3d, there were 9 induced and 10 suppressed genes in NL1-RHg. Substantial changes in gene expression became evident subsequently. At 8d there were 13 induced genes in NL1-RHg. This included putative gland protein G20E03, ubiquitin extension protein, putative gland protein G30C02 and beta-1,4 endoglucanase. However, 1668 genes were found to be suppressed in NL1-RHg. These genes included steroid alpha reductase, serine proteinase and a collagen protein.
These analyses identify a genetic expression signature for these two populations both prior to and subsequently as they undergo an R or S reaction. The identification of genes like steroid alpha reductase and serine proteinase that are involved in feeding and nutritional uptake as being highly suppressed during the R response at 8d may indicate genes that the plant is targeting. The analyses also identified numerous putative parasitism genes that are differentially expressed. The 1668 genes that are suppressed in NL1-RHg, and hence induced in TN8 may represent genes that are important during the parasitic stages of H. glycines development. The potential for different arrays of putative parasitism genes to be expressed in different nematode populations may indicate how H. glycines evolve mechanisms to overcome resistance.
单一的大豆基因型（北京大豆）在抗性（R）和感病（S）反应的感染后最初12小时内，对两个不同的大豆胞囊线虫群体有不同反应。这表明大豆胞囊线虫具有群体特异性的基因表达特征。利用Affymetrix大豆基因芯片上代表7431个转录本的7539个探针集进行微阵列分析，以鉴定侵染北京大豆前的感染前第二阶段幼虫（pi-L2）中的群体特异性基因表达特征。其他分析聚焦于感染后12小时的侵染性L2（i-L2(12h)），以及感染后3天（i-L2(3d)）和8天（i-L2/L3(8d)）的侵染性定居阶段。
比较pi-L2群体（即不亲和群体NL1-RHg与亲和群体TN8）的差异表达和错误发现率（FDR）分析，鉴定出71个在NL1-RHg中相对于TN8被诱导的基因。这些基因包括假定的腺体蛋白G23G12、假定的食道腺蛋白Hgg-20和精氨酸激酶。pi-L2的比较分析鉴定出44个在NL1-RHg中相对于TN8被抑制的基因。这些基因包括一个不同的Hgg-20基因、一种EXPB1蛋白和一种表皮胶原蛋白。到12小时时，NL1-RHg中有7个诱导基因和0个抑制基因。到3天时，NL1-RHg中有9个诱导基因和10个抑制基因。随后基因表达的显著变化变得明显。在8天时，NL1-RHg中有13个诱导基因。这包括假定的腺体蛋白G20E03、泛素延伸蛋白、假定的腺体蛋白G30C02和β-1,4内切葡聚糖酶。然而，发现NL1-RHg中有1668个基因被抑制。这些基因包括类固醇α还原酶、丝氨酸蛋白酶和一种胶原蛋白。
这些分析确定了这两个群体在经历R或S反应之前和之后的基因表达特征。鉴定出在8天的R反应期间参与取食和营养摄取的类固醇α还原酶和丝氨酸蛋白酶等基因被高度抑制，这可能表明植物靶向的基因。分析还鉴定出许多差异表达的假定寄生基因。在NL1-RHg中被抑制并因此在TN8中被诱导的1668个基因可能代表在大豆胞囊线虫发育的寄生阶段重要的基因。不同阵列的假定寄生基因在不同线虫群体中表达的可能性可能表明大豆胞囊线虫如何进化出克服抗性的机制。
