Mitogen-activated protein kinases (MAPKs) are important in regulating plant development as well as stress response. In this study, we genome-widely identified 56 MAPK genes in upland cotton. These MAPK genes unequally distribute on 22 chromosomes of cotton genome, but no MAPK gene is located on At_Chr6, Dt_Chr6, At_Chr13 and Dt_Chr13. The exons and introns in GhMAPK gene family vary widely at the position, number and length. Furthermore, GhMAPK family can be divided into 4 groups (A, B, C and D), and the TEY type of T-loop exists in three groups (A, B and C), but the TDY type of T-loop is only in group D. Further study revealed that some GhMAPK genes (including GhMPK6) are preferentially expressed in elongating fibers. GhMPK6 maintains a high phosphorylation level in elongating fibers, and its phosphorylation was enhanced in fibers by phytohormones brassinosteroid (BR), ethylene and indole-3-acetic acid (IAA). Additionally, GhMPK6 could interact with GhMKK2-2 and GhMKK4, suggesting that GhMKK2-2/4-GhMPK6 module may be involved in phosphorylation of its downstream proteins for regulating fiber elongation of cotton.

丝裂原激活的蛋白激酶（MAPKs）在调节植物发育以及胁迫反应中很重要。在这项研究中，我们在全基因组范围内鉴定了陆地棉上的56个MAPK基因。这些MAPK基因在棉花基因组的22条染色体上分布不均，但是在At_Chr6，Dt_Chr6，At_Chr13和Dt_Chr13上没有MAPK基因。GhMAPK基因家族的外显子和内含子在位置，数量和长度上差异很大。此外，GhMAPK家族可分为4组（A，B，C和D），而TEY型T环存在于三组（A，B和C）中，但TDY型T环仅在D组中。进一步的研究表明，某些GhMAPK基因（包括GhMPK6）优先在延长纤维中表达。GhMPK6在延长的纤维中保持较高的磷酸化水平，并且其纤维化被植物激素油菜素类固醇（BR），乙烯和吲哚-3-乙酸（IAA）增强。此外，GhMPK6可以与GhMKK2-2和GhMKK4相互作用，这表明GhMKK2-2 / 4-GhMPK6模块可能参与其下游蛋白质的磷酸化，从而调节棉花的纤维伸长。