Cloning and functional analysis of<italic> BnMAPK2 </italic>gene in <italic>Brassica napus</italic>

Abstract

<p id="C3">The mitogen-activated protein kinase (MAPK) cascade is involved in plant growth and development and it is in response to a variety of biotic and abiotic stresses. In this study, a<italic> BnMAPK2</italic> (BnaC01g28210D) gene was isolated and cloned from <italic>Brassica napus</italic>. The cDNA and its coding sequence were 1516 bp and 1113 bp in length, respectively, encoding 371 amino acids. Bioinformatics analysis revealed that the molecular weight of BnMAPK2 protein was 42,497.0 kD, the isoelectric point was 6.36, protein instability coefficient was 38.74, it was a hydrophobic protein, and it had STKc_TEY_MAPK_ plant (cd07858) conserved structure domain unique to MAPKs protein, protein secondary level. The alpha helix accounted for the largest proportion of 44.05% in the secondary structure of protein, and there was no signal peptide, which was more closely related to the C group <italic>AtMAPK2</italic> of <italic>Arabidopsis</italic>. The core element prediction indicated that BnMAPK2-P contained related cis-acting elements in response to salicylic acid hormone, heat stress, and light, including TCA-element, HSE, AAAC-motif, and MYB binding sites. Real-time quantitative PCR (qRT-PCR) demonstrated that<italic> BnMAPK2</italic> was expressed in various tissues and organs in <italic>Brassica napus</italic>, which was induced by methyl jasmonate, salicylic acid, H₂O₂, injury, high temperature, and <italic>Sclerotinia sclerotiorum. </italic>The phenotypic data of transgenic <italic>Arabidopsis</italic> lines expressing <italic>BnMAPK2</italic> heterologously showed that compared with the wild type, the overexpression of <italic>BnMAPK2</italic> made the bolting period of <italic>Arabidopsis</italic> plants earlier, and significantly increased plant height, the effective length of main inflorescence, and the number of siliques. We speculated that <italic>BnMAPK2</italic> gene was involved in the regulation of plant growth and development. This study provides reference materials and data support for in-depth exploration of the molecular mechanism of <italic>BnMAPK2 </italic>regulating the growth and development in<italic> Brassica napus</italic>.