Expression analysis of proteinase inhibitor type-2 in response to southern root-knot nematode and its characterization in Nicotiana tabacum

摘要

Proteinase inhibitors (PIs) are polypeptides that occur naturally in a wide range of plants and are considered to be an essential part of the plant’s natural defense system. The aims of this study were to determine effect of PI2-N. tabacum in nematode (Meloidogyne incognita) resistance and its characterize. Resistant (KY9) and susceptible (Ergo) genotypes were inoculated by M. incognita race 2 and total RNA were extracted from roots. Exclusive primers were used for PI2 (Q40561) and EF1α (reference gene) in qPCR to determine PI2 level changes in two, three and four days after inoculation. Results showed significant difference of PI2 expression in resistant and susceptible genotypes in two-four days after inoculation. Bioinformatics analysis revealed PI2 is an unstable protein and has three proteinase inhibitory domains with a trance membrane region. Proteinase inhibitory domains are trypsin and chymotrypsin inhibitor. Alignment and phylogenetic relationship of inhibitor precursor-repeats in Nicotiana sp. revealed seven groups that were variable in sequence. However, they had conserved residues including eight cysteines, a single proline and three Glycine.