Abstract:

In the present study, a non-TIR-NBS-LRR type disease-related gene was cloned by rapid amplification of cDNA ends (RACE) using the high-resistant sugarcane variety NCo376.This gene was termed as SNLR, with the GenBank accession No. of EF155648. The full-length cDNA sequence of SNLR is 2 985 bp, including an open reading frame (ORF) of 2661 bp and the typical 29 bp poly-A. The SNLR gene contained all the four typical conserved motifs of the NBS: P-loop (GMGGVGGKTT), Kinase-2 (LIVLDD), Kinase3a (GSR/KILVIIR) and hydrophobic region (GLPLAL), plus six putative LRR regions. It can be deduced from the hydrophobic character, secondary structure and 3D model analysis of the corresponding coding protein that the SNLR protein was alkalescent, with pI of 7.76 and without any obvious hydrophobic domain; coil and helices were the framework of secondary structure; no transmembrane region was found in its protein 3D model. The gene expression profile under the treatment ofU. scitaminea, SA and H₂O₂ wereinvestigated by Real-time qPCR. Results showed that expression ofsugarcane SNLR gene was influenced by the fungus, SA and H₂O₂, with the expression patterns of “down-up”, “down in the whole process” and “up-down”, respectively. It was inferred that expression of SNLR gene occurs both via an H₂O₂- and SA-dependent pathway. At the same time, SNLR gene was found to be expressed highly in leaves, mildly in stalks and slightly in roots, which indicated its relation to resistance in this aspect.

Key words: Sugarcane, Molecular cloning, Disease resistance gene, Real-time quantity PCR