Genome-wide analysis of mitogen-activated protein (MAP) kinase gene family expression in response to biotic and abiotic stresses in sugarcane

To systematically analyze mitogen-activated protein (MAP) kinase gene families and their expression profiles in sugarcane (Saccharumspp. hybrids; Sh) under diverse biotic and abiotic stresses, we identified 15ShMAPKs, 6ShMAPKKsand 16ShMAPKKKsgenes in the sugarcane cultivar R570 genome. These were also confirmed in oneS. spontaneumgenome and two transcriptome datasets of sugarcane trigged byAcidovorax avenaesubsp. avenae(Aaa) andXanthomonas albilineans(Xa) infections. Phylogenetic analysis revealed that four subgroups were present in each ShMAPK and ShMAPKK family and three sub-families (RAF, MEKK and ZIK) presented in the ShMAPKKK family. Conserved protein motif and gene structure analyses supported the evolutionary relationships of the three families inferred from the phylogenetic analysis. All of theShMAPK,ShMAPKKandShMAPKKKgenes identified inSaccharumspp. R570 were distributed on chromosomes 1-7 and 9-10. RNA-seq and qRT-PCR analyses indicated thatShMAPK07andShMAPKKK02were defense-responsive genes in sugarcane challenged by bothAaaandXastimuli, while some genes were upregulated specifically byAaaandXainfection. Additionally,ShMAPK05acted as a negative regulator under drought and salinity stress, but served as a positive regulator under salicylic acid (SA) treatment.ShMAPK07plays a positive role under drought stress, but a negative role under SA treatment.ShMAPKKK01was negatively modulated by both salinity stress and SA treatment, whereasShMAPKKK06was positively regulated by both of the two stress stimuli. Our results suggest that members of MAPK cascade gene families regulate adverse stress responses through multiple signal transduction pathways in sugarcane.