To gain insight into the changes in the transcriptome of soybean roots during soybean cyst nematode (SCN) infection, we conducted genome-wide gene expression profiling using serial analysis of gene expression (SAGE) combined with Solexa sequencing. More than 3 million tags were generated from the SCN-infected and uninfected roots, and 366941 and 314591 clean UniTags were obtained from SCN-infected and uninfected samples, respectively. In the SCN-infected sample, 48249 UniTags represented 18114 reference genes. In the uninfected control, 46290 UniTags represented 19323 reference genes. Comparison of tag frequencies identified 1405 genes that were expressed at greater levels in SCN-infected roots than in uninfected roots, and 1191 genes that were expressed at lower levels. Quantitative real-time PCR analyses confirmed the changes in mRNA levels observed in our sequencing analyses. A comparable number of genes were upand down-regulated in response to nematode infection, indicating that down-regulation of some genes might be essential in the plant response to nematodes. Our SAGE results showed significant changes in expression of many unreported genes involved in nematode infection. Approximately 7% of tags mapped to the antisense strand of genes, indicating widespread antisense transcription.
LI XiaoYanWANG XueZHANG ShaoPengLIU DaWeiDUAN YuXiDONG Wei
Osmotic stress caused by dehydration or high-salt conditions poses a major environmental challenge for plant growth and development. Many studies have shown that protein kinases are important regulators during osmotic stress in plants. In the present study, we describe GmAAPK, a soybean （Glycine max （L.） Merr.） gene coding for a putative serine/threonine protein kinase （abscisic acid （ABA）-activated protein kinase （AAPK））. The cDNA for GmAAPKis 1 409 bp long and contains a single long open reading frame representing a complete coding region of 359 amino acids. GmAAPKwas mapped onto the D1a＋Q linkage group. Its transcripts are expressed in all tissues, but at high levels in the cotyledon. GmAAPKmRNA was induced by polyethylene glycol, ABA, Ca^2＋ and Na^＋, but not cold （4℃） treatments in soybean leaves. The results suggest that GmAAPK may participate in the regulatory process during osmotic stresses in soybean.
